ALBERT

Notes: The abundance and morphology of microdiamond in dolomite marble from Kumdy-kol in the Kokchetav Massif, are unusual; a previous study estimated the maximum content of diamonds in dolomite marble to be about 2700 carat ton−1. Microdiamond is included primarily in garnet, and occasionally in diopside and phlogopite pseudomorphs after garnet. They are classified into three types on the basis of their morphology: (1) S-type: star-shaped diamond consisting of translucent cores and transparent subhedral to euhedral very fine-grained outer parts; (2) R-type: translucent crystals with rugged surfaces; and (3) T-type: transparent, very fine-grained crystals. The S-type is the most abundant.Micro-Laue diffraction using a 1.6-µm X-ray beam-size demonstrated that the cores of the star-shaped microdiamond represent single crystals. In contrast, the most fine-grained outer parts usually have different orientations compared to the core. Laser–Raman studies indicate that the FWHM (Full Width at Half Maximum) of the Raman band of the core of the S-type diamond is slightly larger than that for the outer parts. Differences in morphology, crystal orientations, and in the FWHM of the Raman band between the core and the fine-grained outer-parts of S-type microdiamond suggest that the star-shaped microdiamond was formed discontinuously in two distinct stages.

Notes: Oscillatory zoning in low δ18O skarn garnet from the Willsboro wollastonite deposit, NE Adirondack Mts, NY, USA, preserves a record of the temporal evolution of mixing hydrothermal fluids from different sources. Garnet with oscillatory zoning are large (1–3 cm diameter) euhedral crystals that grew in formerly fluid filled cavities. They contain millimetre-scale oscillatory zoning of varying grossular–andradite composition (XAdr = 0.13–0.36). The δ18O values of the garnet zones vary from 0.80 to 6.26‰ VSMOW and correlate with XAdr. The shape, pattern and number of garnet zones varies from crystal to crystal, as does the magnitude of the correlated chemistry changes, suggesting fluid system variability, temporal and/or spatial, over the time of garnet growth. The zones of correlated Fe content and δ18O indicate that a high Fe3+/Al, high δ18O fluid mixed with a lower Fe3+/Al and δ18O fluid. The high δ18O, Fe enriched fluids were likely magmatic fluids expelled from crystallizing anorthosite. The low δ18O fluids were meteoric in origin.These are the first skarn garnet with oscillatory zoning reported from granulite facies rocks. Geochronologic, stable isotope, petrologic and field evidence indicates that the Adirondacks are a polymetamorphic terrane, where localized contact metamorphism around shallowly intruded anorthosite was followed by a regional granulite facies overprint. The growth of these garnet in equilibrium with meteoric and magmatic fluids indicates an origin in the shallow contact aureole of the anorthosite prior to regional metamorphism. The zoning was preserved due to the slow diffusion of oxygen and cations in the large garnet and protection from deformation and recrystallization in zones of low strain in thick, rigid, garnetite layers. The garnet provide new information about the hydrothermal system adjacent to the shallowly intruded massif anorthosite that predates regional metamorphism in this geologically complex, polymetamorphic terrane.

Notes: The blueschist and greenschist units on the island of Sifnos, Cyclades were affected by Eocene high-pressure (HP) metamorphism. Using conventional geothermobarometry, the HP peak metamorphic stage was determined at 550–600 °C and 20 kbar, close to the blueschist and the eclogite facies transition. The retrograde P–T paths are inferred with phase diagrams. Pseudosections based on a quantitative petrogenetic grid in the model system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O reveal coeval decompression and cooling for both the blueschist and the greenschist unit. The conditions of the metamorphic peak and those of the retrograde stages conform to a similar metamorphic gradient of 10–12 °C km−1 for both units. The retrograde overprint can be assigned to low-pressure blueschist to HP greenschist facies conditions. This result cannot be reconciled with the (prograde) Barrovian-type event, which affected parts of the Cyclades during the Oligocene to Miocene. Instead, the retrograde overprint is interpreted in terms of exhumation, directly after the HP stage, without a separate metamorphic event. Constraints on the exhumation mechanism are given by decompression-cooling paths, which can be explained by exhumation in a fore-arc setting during on-going subduction and associated crustal shortening. Back-arc extension is only responsible for the final stage of exhumation of the HP units.

Notes: Metabasic rocks from the Adula Nappe in the Central Alps record a regional high-pressure metamorphic event during the Eocene, and display a regional variation in high-pressure mineral assemblages from barroisite, or glaucophane, bearing garnet amphibolites in the north to kyanite eclogites in the central part of the nappe. High-pressure rocks from all parts of the nappe show the same metamorphic evolution of assemblages consistent with prograde blueschist, high-pressure amphibolite or eclogite facies conditions followed by peak-pressure eclogite facies conditions and decompression to the greenschist or amphibolite facies. Average PT calculations (using thermocalc) quantitatively establish nested, clockwise P–T paths for different parts of the Adula Nappe that are displaced to higher pressure and temperature from north to south. Metamorphic conditions at peak pressure increase from about 17 kbar, 640 °C in the north to 22 kbar, 750 °C in the centre and 25 kbar, 750 °C in the south. The northern and central Adula Nappe behaved as a coherent tectonic unit at peak pressures and during decompression, and thermobarometric results are interpreted in terms of a metamorphic field gradient of 9.6 ± 2.0 °C km−1 and 0.20 ± 0.05 kbar km−1. These results constrain the peak-pressure position and orientation of the nappe to a depth of 55–75 km, dipping at an angle of approximately 45° towards the south. Results from the southern Adula Nappe are not consistent with the metamorphic field gradient determined for the northern and central parts, which suggests that the southern Adula Nappe may have been separated from central and northern parts at peak pressure.

Notes: The Priest pluton contact aureole in the Manzano Mountains, central New Mexico preserves evidence for upper amphibolite contact metamorphism and localized retrograde hydrothermal alteration associated with intrusion of the 1.42 Ga Priest pluton. Quartz–garnet and quartz–sillimanite oxygen isotope fractionations in pelitic schist document an increase in the temperatures of metamorphism from 540 °C, at a distance of 1 km from the pluton, to 690 °C at the contact with the pluton. Comparison of calculated temperature estimates with one-dimensional thermal modelling suggests that background temperatures between 300 and 350 °C existed at the time of intrusion of the Priest pluton. Fibrolite is found within 300 m of the Priest pluton in pelitic and aluminous schist metamorphosed at temperatures 〉580 °C. Coexisting fibrolite and garnet in pelitic schist are in oxygen isotope equilibrium, suggesting these minerals were stable reaction products during peak metamorphism. The fibrolite-in isograd is coincident with the staurolite-out isograd in pelitic schist, and K-feldspar is not observed with the first occurrence of fibrolite. This suggests that the breakdown of staurolite and not the second sillimanite reaction controls fibrolite growth in staurolite-bearing pelitic schist. Muscovite-rich aluminous schist locally preserves the Al2SiO5 polymorph triple-point assemblage – kyanite, andalusite and fibrolite. Andalusite and fibrolite, but not kyanite, are in isotopic equilibrium in the aluminous schist. Co-nucleation of fibrolite and andalusite at 580 °C in the presence of muscovite and absence of K-feldspar suggests that univariant growth of andalusite and fibrolite occurred. Kyanite growth occurred during an earlier regional metamorphic event at a temperature nearly 80 °C lower than andalusite and fibrolite growth. Quartz–muscovite fractionations in hydrothermally altered pelitic schist and quartzite are small or negative, suggesting that late isotopic exchange between externally derived fluids and muscovite, but not quartz, occurred after peak contact metamorphism and that hydrothermal alteration in pelitic schist and quartzite occurred below the closure temperature of oxygen self diffusion in quartz (〈500 °C).

Notes: Abstract Concordant U–Pb ages of c. 530–510 Ma and c. 470–420 Ma on titanite from calcsilicate, orthogneiss and amphibolite rocks constrain the age of high-T metamorphism in the Early Palaeozoic mobile belt at the western margin of Proterozoic Gondwana (Argentina, 26–29°S). The U–Pb ages document the time of titanite formation at high-T conditions according to the stable mineral paragenesis and occurrence of titanite in the metamorphic fabric. The presence of migmatite at all sample sites indicates temperatures were 〉 c. 650 °C. Titanite formed at similar metamorphic conditions at different times on the regional and on the outcrop scale. The titanite crystals preserved their U–Pb isotopic signatures and chemical composition under ongoing upper amphibolite to granulite facies temperatures. Different thermal peaks or deformations are only detected by the different U–Pb ages and not by changes in the mineral paragenesis or metamorphic fabric of the samples. The range of U–Pb ages, e.g. in the Ordovician and Silurian (c. 470, 460, 440, 430, 420 Ma), is interpreted as the effect polyphase deformation with deformation-enhanced recrystallization of titanite and/or different thermal peaks during a long-standing, geographically fixed, high-T regime in the mid-crust of a continental magmatic arc. A clear correlation of the different ages with distinct tectonic events, e.g. collision of terranes, is not possible based on the present knowledge of the region.

Notes: Abstract The garnet blueschists from the Ile de Groix (Armorican Massif, France) contain millimetre- to centimetre-sized pseudomorphs consisting of an aggregate of chlorite, epidote and paragonite. The pseudomorphed phase developed at a late stage of the deformation history, because it overgrows a glaucophane–epidote–titanite foliation. Garnet growth occurred earlier than the beginning of the ductile deformation, and thus garnet is also included in the pseudomorphs. Microprobe analyses show that garnet is strongly zoned, with decreasing spessartine and increasing almandine and pyrope contents from core to rim. Grossular content is higher in garnet cores (about 35 mole%) compared to garnet rims (about 30 mole%). Blue amphibole has glaucophane compositions with a low Fe3+ content and become more magnesian when inclusions in garnet (XMg = 0.62–0.65) are compared with matrix grains (XMg = 0.67–0.70). Matrix epidote has a pistacite content of about 50 mole%. On the basis of their shape and the nature of the breakdown products, the pseudomorphs are attributed to lawsonite. A numerical model (using Thermocalc) has been developed in order to understand the reactions controlling both the growth and the breakdown of lawsonite. Lawsonite growth could have taken place through the continuous hydration reaction Chl + Ep + Pg + Qtz + Vap = Gln + Lws, followed by the fluid-absent reaction Chl + Ep + Pg = Grt + Gln + Lws. Peak P–T conditions are estimated at about 18–20 kbar, 450 °C. This indicates that lawsonite growth took place at increasing P and T, hence can be used as a geobarometer in the buffering assemblage garnet–glaucophane–epidote. The final part of the history is recorded by lawsonite breakdown, after cessation of the ductile deformation, and recording the earliest stages of the exhumation.

Notes: Previous models of hydrodynamics in contact metamorphic aureoles assumed flow of aqueous fluids, whereas CO2 and other species are also common fluid components in contact metamorphic aureoles. We investigated flow of mixed CO2–H2O fluid and kinetically controlled progress of calc-silicate reactions using a two-dimensional, finite-element model constrained by the geological relations in the Notch Peak aureole, Utah. Results show that CO2 strongly affects fluid-flow patterns in contact aureoles. Infiltration of magmatic water into a homogeneous aureole containing CO2–H2O sedimentary fluid facilitates upward, thermally driven flow in the inner aureole and causes downward flow of the relatively dense CO2-poor fluid in the outer aureole. Metamorphic CO2-rich fluid tends to promote upward flow in the inner aureole and the progress of devolatilization reactions causes local fluid expulsion at reacting fronts. We also tracked the temporal evolution of P-T-XCO2conditions of calc-silicate reactions. The progress of low- to medium-grade (phlogopite- to diopside-forming) reactions is mainly driven by heat as the CO2 concentration and fluid pressure and temperature increase simultaneously. In contrast, the progress of the high-grade wollastonite-forming reaction is mainly driven by infiltration of chemically out-of-equilibrium, CO2-poor fluid during late-stage heating and early cooling of the inner aureole and thus it is significantly enhanced when magmatic water is involved. CO2-rich fluid dominates in the inner aureole during early heating, whereas CO2-poor fluid prevails at or after peak temperature is reached. Low-grade metamorphic rocks are predicted to record the presence of CO2-rich fluid, and high-grade rocks reflect the presence of CO2-poor fluid, consistent with geological observations in many calc-silicate aureoles. The distribution of mineral assemblages predicted by our model matches those observed in the Notch Peak aureole.

Notes: The Swakane Gneiss and the overlying Napeequa Complex in the North Cascade range, Washington, were metamorphosed and deformed during development of a Cretaceous-Paleogene continental arc, and are among the structurally deepest exposed rocks within the Cordilleran arcs of North America. Peak metamorphic conditions in both the Swakane Gneiss and Napeequa Complex were c. 640–750 °C, 9–12 kbar. Clockwise paths and widespread evidence for high-P metamorphism in meta-supracrustal rocks (burial to 〉40 km) document major vertical tectonic motion during arc construction and unroofing.These and other moderately high-pressure rocks in the North Cascades-Coast Mountains experienced a dramatically different tectonometamorphic history than metamorphic rocks within other Cordilleran arcs. The exhumed arc complexes of the Sierra Nevada and Peninsular Ranges are dominated by relatively low-P metamorphic and plutonic rocks (typically 〈6 kbar). There is no evidence that the northern Cordillera was thickened to a greater degree than these other belts, suggesting that the greater magnitude of vertical motion in the Cascades may have been related to exhumation mechanisms: Eocene extension in the northern Cordillera vs. erosional unroofing in the central and southern Cordillera.

Notes: High-pressure (HP) granulites and eclogitized metagabbro are exposed along an orogen-parallel high-P belt that was developed at c. 1050–1020 Ma in the NE Grenville Province. Among these rocks, mafic granulites derived from a Labradorian anorthosite suite of the Lelukuau terrane contain garnet, Al-Na diopside, and, depending on bulk composition, plagioclase and kyanite. Moreover, the distribution of phases is influenced by the original igneous texture. For instance, in high XMgO leucocratic varieties, garnet porphyroblasts nucleated together with kyanite in An-rich cores of plagioclase domains whereas in low XMgO rocks garnet occurs together with clinopyroxene within formerly igneous ferromagnesian domains and kyanite is missing. In contrast, garnet pseudomorphs after igneous plagioclase in melanocratic varieties display evidence of earlier corona development. Metamorphic textures are consistent with a two stage evolution: (a) development of garnet and Al-Na-diopside (Cpx1) under high-P metamorphic conditions, concomitant with elimination of plagioclase in the mesocratic to melanocratic varieties; and (b) partial loss of Al-Na from Cpx1 resulting in production of new andesitic plagioclase, and growth of new clinopyroxene (Cpx2) after garnet and quartz in leucocratic to mesocratic rocks consistent with decompression. Widespread equilibrium textures between garnet-Pl2-Cpx2 and/or reset Cpx1 are consistent with development at the thermal peak. Estimated P–T conditions for the presumed thermal peak fall in the range 1500–1800 MPa and 800–900 °C and are comparable to those recorded by eclogitized gabbros from other parts of the high-P belt of the NE Grenville province. Low jadeite content of clinopyroxene from the HP granulites is attributed to the low bulk Na2O/(Na2O + CaO) of these rocks relative to common basaltic compositions. Scarcity of apparent retrograde textural overprint in both the HP granulites and the eclogites suggests fast subsequent cooling, consistent with extrusion of the high-P belt towards the foreland shortly after the metamorphic peak.

Notes: The upper deck of the East Athabasca mylonite triangle (EAmt), northern Saskatchewan, Canada, contains mafic granulites that have undergone high P–T metamorphism at conditions ranging from 1.3 to 1.9 GPa, 890–960 °C. Coronitic textures in these mafic granulites indicate a near-isothermal decompression path to 0.9 GPa, 800 °C. The Godfrey granite occurs to the north adjacent to the upper deck high P–T domain. Well-preserved corona textures in the Godfrey granite constrain igneous crystallization and early metamorphism in the intermediate-pressure granulite field (Opx + Pl) at 1.0 GPa, 775 °C followed by metamorphism in the high pressure granulite field (Grt + Cpx + Pl) at 1.2 GPa, 860 °C. U–Pb geochronology of zircon in upper deck mafic granulite yields evidence for events at both c. 2.5 Ga and c. 1.9 Ga. The oldest zircon dates are interpreted to constrain a minimum age for crystallization or early metamorphism of the protolith. A population of 1.9 Ga zircon in one mafic granulite is interpreted to constrain the timing of high P–T metamorphism. Titanite from the mafic granulites yields dates ranging from 1900 to 1894 Ma, and is interpreted to have grown along the decompression path, but still above its closure temperature, indicating cooling following the high P–T metamorphism from c. 960–650 °C in 4–10 Myr. Zircon dates from the Godfrey granite indicate a minimum crystallization age of 2.61 Ga, without any evidence for 1.9 Ga overgrowths. The data indicate that an early granulite facies event occurred at c. 2.55–2.52 Ga in the lower crust (c. 1.0 GPa), but at 1.9 Ga the upper deck underwent high P–T metamorphism, then decompressed to 0.9–1.0 GPa. Juxtaposition of the upper deck and Godfrey granite would have occurred after or been related to this decompression. In this model, the high P–T rocks are exhumed quickly following the high pressure metamorphism. This type of metamorphism is typically associated with collisional orogenesis, which has important implications for the Snowbird tectonic zone as a fundamental boundary in the Canadian Shield.

Notes: Orthopyroxene-free garnet + clinopyroxene + plagioclase ± quartz-bearing mineral assemblages represent the paragenetic link between plagioclase-free eclogite facies metabasites and orthopyroxene-bearing granulite facies metabasites. Although these assemblages are most commonly developed under P–T conditions consistent with high pressure granulite facies, they sometimes occur at lower grade in the amphibolite facies. Thus, these assemblages are characteristic but not definitive of high pressure granulite facies. Compositional factors favouring their development at amphibolite grade include Fe-rich mineral compositions, Ca-rich garnet and plagioclase, and Ti-poor hornblende. The generalized reaction that accounts for the prograde development of garnet + clinopyroxene + plagioclase ± quartz from a hornblende + plagioclase + quartz-bearing (amphibolite) precursor is Hbl + Pl + Qtz=Grt + Cpx + liquid or vapour, depending on whether the reaction occurs above or below the solidus. There are significant discrepancies between experimental and natural constraints on the P–T conditions of orthopyroxene-free garnet + clinopyroxene + plagioclase ± quartz-bearing mineral assemblages and therefore on the P–T position of this reaction. Semi-quantitative thermodynamic modelling of this reaction is hampered by the lack of a melt model and gives results that are only moderately successful in rationalizing the natural and experimental data.

Notes: Schlieren are trains of platy or blocky minerals, typically the ferromagnesian minerals and accessory phases, that occur in granites and melt-rich migmatites, such as diatexites. They have been considered as: (1) unmelted residue from xenoliths or the source region; (2) mineral accumulations formed during magma flow; (3) compositional layering; and (4) sites of melt loss. In order to help identify schlieren-forming processes in the diatexites at St Malo, differences in the size, shape, orientation, distribution and composition of the biotite from schlieren and from their hosts have been investigated.Small biotite grains are much less abundant in the schlieren than in their hosts. Schlieren biotite grains are generally larger, have greater aspect ratios and have, except in hosts with low (〈 10%) biotite contents, a much stronger shape preferred orientation than host biotite. The compositional ranges of host and schlieren biotite are similar, but schlieren biotite defines tighter, sharper peaks on composition-frequency plots. Hosts show magmatic textures such as imbricated (tiled), unstrained plagioclase. Some schlieren show only magmatic textures (tiled biotite, no crystal-plastic strain features), but many have textures indicating submagmatic and subsolidus deformation (e.g. kinked grains) and these schlieren show the most extensive evidence for recrystallization.Magmas at St Malo initially contained a significant fraction of residual biotite and plagioclase crystals; smaller biotite grains were separated from the larger plagioclase crystals during magma flow. Since plagioclase was also the major, early crystallizing phase, the plagioclase-rich domains developed rapidly and reached the rigid percolation threshold first, forcing further magma flow to be concentrated into narrowing melt-rich zones where the biotite had accumulated, hence increasing shear strain and the degree of shape preferred orientation in these domains. Schlieren formed in these domains as a result of grain contacts and tiling in the grain inertia-regime. Final amalgamation of the biotite aggregates into schlieren involved volume loss as melt trapped between grains was expelled after the rigid percolation threshold was reached in the biotite-rich layers.

Notes: The eclogite type locality in the Eastern Alps (the Koralpe and Saualpe region) is the largest region in the Eastern Alps that preserves high-pressure metamorphic rocks from the Eo-Alpine orogenic event of the Cretaceous age. Thermobarometric data from the metapelitic gneisses in the region indicate that a metamorphic field gradient across the region can be divided into three parts. The northern part shows continuously increasing P–T from 10 ± 1.5 to 14 ± 1.5 kbar and 500 ± 68 to 700 ± 68 °C over a distance of 40 km. The continuous increase in P–T indicates that no major tectonic boundaries were active in this part during the Eo-Alpine orogeny. Small discontinuities in the pressure gradient of the northern part can be correlated with more localized deformation. The central part exposes amphibolite–eclogite facies rocks with 15 ± 1.5 kbar and 700 ± 68 °C over about 20 km length. The southern part shows decreasing P–T conditions from 15 ± 1.5 to 10 ± 1.5 kbar and 700 ± 68 to 600 ± 63 °C over a distance of 10 km beyond which conditions remain roughly constant for the remainder of the profile.Overall, the field gradient is characterized by: (i) an increase in age with decreasing metamorphic grade and (ii) a T/P ratio that is lower than common metamorphic geotherms. The age–grade relationship is consistent with the timing relationship along piezothermal arrays predicted by simple models for regional metamorphism. However, the T/P ratio of the field gradient is inconsistent with such an interpretation. These inconsistencies indicate that the profile is not simply an obliquely exposed crustal section. We suggest that the exhumation of the transect is best explained with a two dimensional model of an extruding wedge, as has recently been suggested as a typical scenario for other large scale compressional orogens.

Notes: A largely undocumented region of eclogite associated with a thick blueschist unit occurs in the Kotsu area of the Sanbagawa belt. The composition of coexisting garnet and omphacite suggests that the Kotsu eclogite formed at peak temperatures of around 600 °C synchronous with a penetrative deformation (D1). There are local significant differences in oxygen fugacity of the eclogite reflected in mineral chemistries. The peak pressure is constrained to lie between 14 and 25 kbar by microstructural evidence for the stability of paragonite throughout the history recorded by the eclogite, and the composition of omphacite in associated eclogite facies pelitic schist. Application of garnet-phengite-omphacite geobarometry gives metamorphic pressures around 20 kbar. Retrograde metamorphism associated with penetrative deformation (D2) is in the greenschist facies. The composition of syn-D2 amphibole in hematite-bearing basic schist and the nature of the calcium carbonate phase suggest that the retrograde P–T path was not associated with a significant increase or decrease in the ratio of P–T conditions following the peak of metamorphism. This P–T path contrasts with the open clockwise path derived from eclogite of the Besshi area. The development of distinct P–T paths in different parts of the Sanbagawa belt shows the shape of the P–T path is not primarily controlled by tectonic setting, but by internal factors such as geometry of metamorphic units and exhumation rates.

Notes: Previous studies suggest that the metamorphic evolution of the ultrahigh-pressure garnet peridotite from Alpe Arami was characterized by rapid subduction to a depth of c. 180 km with partial chemical equilibration at c. 5.9 Gpa/1180 °C and an initial stage of near-isothermal decompression followed by enhanced cooling. In this study, average cooling rates were constrained by diffusion modelling on retrograde Fe–Mg zonation profiles across garnet porphyroclasts. Considering the effects of temperature, pressure and garnet bulk composition on the Fe–Mg interdiffusion coefficient, cooling rates of 380–1600 °C Myr−1 for the interval from 1180 to 800 °C were obtained. Similar or even higher average cooling rates resulted from thermal modelling, whereby the characteristics of the calculated temperature-time path depend on the shape and size of the hot peridotite body and the boundary conditions of the cooling process. The very high cooling rates obtained from both geospeedometry and thermal modelling imply extremely fast exhumation rates of c. 15 mm yr−1 or more. These results agree with the range of exhumation rates (16–50 mm yr−1) deduced from geochronological results. It is suggested that the Alpe Arami peridotite passively returned towards the surface as part of a buoyant sliver, caused as a consequence of slab breakoff.

Notes: We report SHRIMP U–Th–Pb monazite, conventional U–Pb titanite, Sm–Nd garnet and Rb–Sr muscovite and biotite ages for metamorphic rocks from the Danba Domal Metamorphic Terrane in the eastern Songpan-Garzê Orogenic Belt (eastern Tibet Plateau). These ages are used to determine the timing of polyphase metamorphic events and the subsequent cooling history. The oldest U–Th–Pb monazite and Sm–Nd garnet ages constrain an early Barrovian metamorphism (M1) in the interval c. 204–190 Ma, coincident with extensive Indosinian granitic magmatism throughout the Songpan-Garzê Orogenic Belt. A second, higher-grade sillimanite-grade metamorphic event (M2), recorded only in the northern part of the Danba terrane, was dated at c. 168–158 Ma by a combination of U–Th–Pb monazite and titanite and Sm–Nd garnet ages. It is suggested that M1 was a thermal event that affected the entire orogenic belt while M2 may represent a local thermal perturbation. Rb–Sr muscovite ages range from c. 138–100 Ma, whereas Rb–Sr biotite ages cluster at c. 34–24 Ma. These ages document regional cooling at rates of c. 2–3 °C Myr−1 following the M1 peak for most of the terrane. However, those parts of the terrane affected by the higher-temperature M2 event (e.g. the migmatite zone) experienced initially more rapid (c. 8 °C Myr−1) cooling after peak M2 before joining the regional slow cooling path defined by the rest of the terrane at c. 138 Ma. Regional slow cooling between c. 138 and c. 30 Ma is thought to be the result of post-tectonic isostatic uplift after extensive crustal thickening caused by collision of the South and North China Blocks. The clustering of biotite Rb–Sr ages marks the onset of rapid uplift across the entire terrane commencing at c. 30–20 Ma. This cooling history is shared with many other regions of the Tibet Plateau, suggesting that uplift of the Tibet Plateau (including the Songpan-Garzê Orogenic Belt) occurred predominantly in the last c. 30 Myr as a response to the continuing northwards collision of India with Eurasia.

Notes: Recent studies have used the relative rotation axis of sigmoidal and spiral-shaped inclusion trails, known as Foliation Inflexion/Intersection Axis (FIA), to investigate geological processes such as fold mechanisms and porphyroblast growth. The geological usefulness of this method depends upon the accurate measurement of FIA orientations and correct correlation of temporally related FIAs. This paper uses new data from the Canton Schist to assess the variation in FIA orientations within and between samples, and evaluates criteria for correlating FIAs. For the first time, an entire data set of FIA measurements is published, and data are presented in a way that reflects the variation in FIA orientations within individual samples and provides an indication of the reliability of the data. Analysis of 61 FIA trends determined from the Canton Schist indicate a minimum intrasample range in FIA orientations of 30°. Three competing models are presented for correlation of these FIAs, and each of the models employ different correlation criteria. Correlation of FIAs in Model 1 is based on relative timing and textural criteria, while Model 2 uses relative timing, orientation and patterns of changing FIA orientations, and Model 3 uses relative timing and FIA orientation as correlation criteria. Importantly, the three models differ in the spread of FIA orientations within individual sets, and the number of sets distinguished in the data. Relative timing is the most reliable criterion for correlation, followed by textural criteria and patterns of changing FIA orientations from core to rim of porphyroblasts. It is proposed that within a set of temporally related FIAs, the typical spread of orientations involves clustering of data in a 60° range, but outliers occur at other orientations including near-normal to the peak distribution. Consequently, in populations of FIA data that contain a wide range of orientations, correlation on the basis of orientation is unreliable in the absence of additional criteria. The results of this study suggest that FIAs are best used as semiquantitative indicators of bulk trends rather than an exact measurement for the purpose of quantitative analyses.

Notes: Documentation of pressure–temperature (P–T) histories across an epidote-amphibolite facies culmination provides new insight into the tectono-thermal evolution of the Brooks Range collisional orogen. Thermobarometry reveals that the highest grade rocks formed at peak temperatures of 560–600 °C and at pressures of 8–9.5 kbar. The thermal culmination coincides with the apex of a structural dome defined by oppositely dipping S2 crenulation cleavages suggesting post-metamorphic doming. South of the thermal culmination, greenschist facies and lowermost epidote-amphibolite facies rocks preserve widespread evidence for an early blueschist facies metamorphism. In contrast, no evidence for an early blueschist facies metamorphism was found in similar grade rocks of the northern flank, indicating that the southern flank underwent initial deeper burial during southward underthrusting of the continental margin. Thus, while the dome shows a symmetric distribution of peak temperatures, the P–T paths followed by the two flanks must have varied. This variation suggests that final thermal re-equilibration to greenschist and epidote–amphibolite facies conditions did not result from a simple process of southward underthrusting followed by thermal re-equilibration from the bottom upward. The new data are inconsistent with a previous model that invokes such re-equilibration, along with northward thrusting of epidote–amphibolite facies rocks over lower grade rocks presently on the southern flank of the culmination, to produce an inverted metamorphic field gradient. Instead, it is suggested that following blueschist facies metamorphism, rocks of the southern and northern flanks were juxtaposed, during which time the more deeply buried south flank was partially emplaced above rocks to the north, where they escaped Albian epidote–amphibolite facies overprinting. Porphyroblast growth, which post-dates the main fabric on the north flank of the culmination may be the result of Albian thermal re-equilibration following this deformation. Post-metamorphic doming resulted from a combination of Albian-Cenomanian extension and Tertiary deformation.

Notes: Spiral inclusion trails in garnet porphyroblasts are likely to have formed due to simultaneous growth and rotation of the crystals, during syn-metamorphic deformation. Thus, they contain information on the strain rate of the rock. Strain rates may be interpreted from such inclusion trails if two functions are known: (1) The relationship between rotation rate and shear strain rate; (2) the growth rate of the crystal. We have investigated details of both functions using a garnetiferous mica schist from the eastern European Alps as an example. The rotation rate of garnet porphyroblasts was determined using finite element modelling of the geometrical arrangement of the crystals in the rock. The growth rate of the porphyroblasts was determined by using the major and trace element distributions in garnet crystals, thermodynamic pseudosections and information on the grain size distribution. For the largest porphyroblast size fraction (size L=12 mm) we constrain a growth interval between 540 and 590 °C during the prograde evolution of the rock. Assuming a reasonable heating rate and using the angular geometry of the spiral inclusion trails we are able to suggest that the mean strain rate during crystal growth was of the order of 〈inlineGraphic alt="inline image" href="urn:x-wiley:02634929:JMG441:JMG_441_mu1" location="equation/JMG_441_mu1.gif"/〉=6.6 × 10−14 s−1. These estimates are consistent with independent estimates for the strain rates during the evolution of this part of the Alpine orogen.

Notes: Mineral textures in metapelitic granulites from the northern Prince Charles Mountains, coupled with thermodynamic modelling in the K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 (KFMASHTO) model system, point to pressure increasing with increasing temperature on the prograde metamorphic path, followed by retrograde cooling (i.e. an anticlockwise P–T path). Textural evidence for the increasing temperature part of the path is given by the breakdown of garnet and biotite to form orthopyroxene and cordierite in sillimanite-absent rocks, and through the break-down of biotite and sillimanite to form spinel, cordierite and garnet in more aluminous assemblages. This is equated to the advective addition of heat from the regional emplacement of granitic and charnockitic magmas dated at c. 980 Ma. A subsequent increase in pressure, inferred from the break-down of spinel and quartz to sillimanite, cordierite and garnet in aluminous rocks, is attributed to crustal thickening related to upright folding dated at 940–910 Ma. The terrane attained peak metamorphic temperatures of c. 880 °C at pressures of c. 6.0–6.5 kbar during this event. Subsequent cooling is inferred from the localised breakdown of cordierite and garnet to form biotite and sillimanite that developed in the latter stages of the same event. The textural observations described are interpreted via the application of P–T and P–T–X pseudosections. The latter show that most rock compositions preserve only fragments of the overall P–T path; a result of different rock compositions undergoing mineral assemblage changes, or changes in mineral modal abundance, on different sections of the P–T path. The results also suggest that partial melting during granulite facies metamorphism, coupled with melt loss and dehydration, initiated a switch from pervasive ductile, to discrete ductile/brittle deformation, during retrograde cooling.

Notes: Fluid flow at greenschist facies conditions during exhumation of the western Alps occurred in several penecontemporaneous systems, including shear zones at lithological contacts, deformed contacts between serpentinite bodies and metabasalts, albite veins within metabasalts, and calcite + quartz veins within calcareous schists. Fluid flow in shear zones that juxtapose metasediments and ophiolitic rocks within the Piemonte Unit reset O and H isotope ratios. δ18O values are buffered by the wall rocks; however, calculated fluid δ2H values are similar within all the shear zones suggesting that they formed an interconnected network. The similarity of δ2H values of the sheared rocks and those of unsheared calcareous schists suggests that the fluids were derived from, or had equilibrated with, the schists that envelop the ophiolite rocks. Time-integrated fluid fluxes at the sheared contacts estimated from changes in Si in metabasalts were up to 105 m3 m−2, with the fluid flowing up temperature driven either by topography or seismic pumping. Individual shear zones were active for c. 2–3 Myr, implying average fluid fluxes of up to 10−9 m3 m−2 s−1. Rocks in shear zones within the ophiolite away from contacts with the metasediments show much less marked isotopic and geochemical changes, implying that fluid volumes decreased into the ophiolite unit, consistent with the source of fluids being the metasediments. Fluids were generated by dehydration reactions that were intersected during exhumation and, while many rocks show the affects of fluid–rock interaction, large-scale fluid flow between major units was not common.

Notes: Eclogites from the south Tianshan, NW China are grouped into two types: glaucophane and hornblende eclogites, composed, respectively, of garnet + omphacite + glaucophane + paragonite + epidote + quartz and garnet + omphacite + hornblende (sensu lato) + paragonite + epidote + quartz, plus accessory rutile and ilmenite. These eclogites are diverse both in mineral composition and texture not only between the two types but also among the different selected samples within the glaucophane eclogite. Using thermocalc 3.1 and recent models of activity–composition relation for minerals, a P–T projection and a series of P–T pseudosections for specific samples of eclogite have been calculated in the system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O (NCFMASH) with quartz and water taken to be in excess. On the basis of these phase diagrams, the phase relations and P–T conditions are well delineated. The three selected samples of glaucophane eclogite AK05, AK11 and AK17 are estimated to have peak P–T conditions, respectively, of 540–550 °C at c. 16 kbar, c. 560 °C at 15–17 kbar and c. 580 °C at 15–19 kbar, and two samples of hornblende eclogite AK10 and AK30 of 610–630 °C and 17–18 kbar. Together with H2O-content contours in the related P–T pseudosections and textural relations, both types of eclogite are inferred to show clockwise P–T paths, with the hornblende eclogite being transformed from the glaucophane eclogite assemblage dominantly through increasing temperature.

Notes: This study uses field, petrographic and geochemical methods to estimate how much granitic melt was formed and extracted from a granulite facies terrane, and to determine what the grain- and outcrop-scale melt-flow paths were during the melt segregation process. The Ashuanipi subprovince, located in the north-eastern Superior Province of Quebec, is a large (90 000 km2) metasedimentary terrane, in which 〉 85% of the metasediments are of metagreywacke composition, that was metamorphosed at mid-crustal conditions (820–900 °C and 6–7 kbar) in a late Archean dextral, transpressive orogen. Decrease in modal biotite and quartz as orthopyroxene and plagioclase contents increase, together with preserved former melt textures indicate that anatexis was by the biotite dehydration reaction: biotite + quartz + plagioclase = melt + orthopyroxene + oxides. Using melt/orthopyroxene ratios for this reaction derived from experimental studies, the modal orthopyroxene contents indicate that the metagreywacke rocks underwent an average of 31 vol% partial melting.The metagreywackes are enriched in MgO, CaO and FeOt and depleted in SiO2, K2O, Rb, Cs, and U, have lower Rb/Sr, higher Rb/Cs and Th/U ratios and positive Eu anomalies compared to their likely protolith. These compositions are modelled by the extraction of between 20 and 40 wt %, granitic melt from typical Archean low-grade metagreywackes. A simple mass balance indicates that about 640 000 km3 of granitic melt was extracted from the depleted granulites.The distribution of relict melt at thin section- and outcrop-scales indicates that in layers without leucosomes melt extraction occurred by a pervasive grain boundary (porous) flow from the site of melting, across the layers and into bedding planes between adjacent layers. In other rocks pervasive grain boundary flow of melt occurred along the layers for a few, to tens of centimetres followed by channelled flow of melt in a network of short interconnected and structurally controlled conduits, visible as the net-like array of leucosomes in some outcrops. The leucosomes contain very little residual material (〈 5% biotite + orthopyroxene) indicating that the melt fraction was well separated from the residuum left in situ as melt-depleted granulite. Only 1–3 vol percentage melt remained in the melt-depleted granulites, hence, the extraction of melt generated by biotite dehydration melting in these granulites, was virtually complete under conditions of natural melting and strain rates in a contractional orogen.

Notes: Abstract Three experiments were undertaken to investigate the influence of seed mixture on the establishment of a target grassland community on a site with high available phosphorus. In the first experiment autumn- and spring-sown commercial seed mixtures were compared with seed harvested from a nature reserve with respect to their ability to produce an inundation grassland community similar to that described by the British National Vegetation Classification (NVC) as Agrostis stolonifera–Alopecurus geniculatus grassland (MG13). In the second experiment the composition and sowing rate of a commercial seed mixture were altered to investigate whether these factors were significant in the establishment of a sward similar to MG13. Similarly, in the third experiment the composition of a commercial seed mixture designed to achieve an alternative community, Cynosurus cristatus–Caltha palustris grassland (NVC code MG8), was sown. The vegetation resulting from each of these treatments was monitored with permanent quadrats for a 3-year period, and the hydrological regime of each quadrat location was modeled and quantified. The results showed that seed mixture, timing of sowing, and seeding rate had an initial effect on the vegetation that established. However, by the third year of monitoring there were no significant differences between these treatments, and hydrological regime had become the most important factor in determining the distribution of species. The vegetation was less diverse than predicted from germination tests and decreased in diversity over the monitoring period. It is suggested that this may be a result of the hydrological regime being unsuitable for several of the sown species or due to the extremely high available phosphorus concentration in the soil. This study highlights the need to understand the soil and hydrological conditions of a site before choosing a target community and designing a seed mixture.

Notes: Abstract Introduced perennial grasses are one of the greatest constraints to prairie restoration. Herbicides suppress but do not eliminate introduced grasses, so we explored the interaction of herbicide with two additional controls: heavy clipping (to simulate grazing) and competition from native species. A 50-year-old stand of the introduced perennial grass Agropyron cristatum (crested wheatgrass) in the northern Great Plains was seeded with native grasses and treated with herbicide annually for 7 years in a factorial experiment. Clipping was applied as a subplot treatment in the final 3 years. Both herbicide and clipping significantly reduced the cover of A. cristatum, but clipping produced an immediate and consistent decrease, whereas herbicide control varied among years. The cover of A. cristatum decreased significantly with increasing cover of a seeded native grass, Bouteloua gracilis (blue grama), suggesting that both top-down (i.e., grazing) and bottom-up (i.e., resource competition) strategies can contribute to A. cristatum control. No treatment had any effect on the seed bank of A. cristatum. Even in the most effective control treatments, A. cristatum persisted at low amounts (approximately 5% cover) throughout the experiment. The cover of B. gracilis increased significantly with seed addition and herbicide, and, after 7 years, was similar to that in undisturbed prairie. The total cover of native species increased significantly with clipping and herbicide, and species richness was significantly higher in plots receiving herbicide. Clipping season had no effect on any variable. In summary, no method extirpated A. cristatum, but clipping reduced its cover by 90% and doubled the cover of native species. Extirpation might not be a realistic goal, but relatively simple management allowed coexistence of native species.

Notes: Abstract The reduction and fragmentation of forest habitats is expected to have profound effects on plant species diversity as a consequence of the decreased area and increased isolation of the remnant patches. To stop the ongoing process of forest fragmentation, much attention has been given recently to the restoration of forest habitat. The present study investigates restoration possibilities of recently established patches with respect to their geographical isolation. Because seed dispersal events over 100 m are considered to be of long distance, a threshold value of 100 m between recent and old woodland was chosen to define isolation. Total species richness, individual patch species richness, frequency distributions in species occurrences, and patch occupancy patterns of individual species were significantly different among isolated and nonisolated stands. In the short term no high species richness is to be expected in isolated stands. Establishing new forests adjacent to existing woodland ensures higher survival probabilities of existing populations. In the long term, however, the importance of long-distance seed dispersal should not be underestimated because most species showed occasional long-distance seed dispersal. A clear distinction should be made between populations colonizing adjacent patches and patches isolated from old woodland. The colonization of isolated stands may have important effects on the dynamics and diversity of forest networks, and more attention should be directed toward the genetic traits and viability of founding populations in isolated stands.

Notes: Abstract The effects of the earthworm Pontoscolex corethrurus (Muller) on the rate of mineralization of cattle dung-amended iron (Fe2+) ore mine wastes and its preference for partially decomposed leaf litter with contrasting chemical composition were studied in pot trials. The growth and survival rates of earthworms showed significant positive correlations with percent of organic matter. During 96 days of exposure, the earthworms significantly increased exchangeable Ca2+, Mg2+, PO43− and NH4-N. Iron ore mine wastes amended with 5–10% organic matter supported earthworm fauna better than mine wastes amended with 0–3% organic matter. The leaf litter preference shown by the earthworm was, in descending order, Phyllanthus reticulatus, Tamarindus indica, Anacardium occidentale, Casuarina equisetifolia, Acacia auriculiformis, and Eucalyptus camaldulensis. A significant positive correlation was observed between the survival and growth rates of earthworms and the nutrient contents of partially decomposed leaf litter. The first three plant species were significantly richer in nutrients, mainly organic carbon, calcium, phosphorus, and nitrogen, than the other two plant species. Acacia auriculiformis and E. camaldulensis litter were preferred less because of their high lignin and polyphenolic compounds, despite being rich in other macronutrients like nitrogen and phosphorus. It is concluded that the introduction of P. corethrurus to cattle dung-amended (5–10%) iron ore mine wastes or revegetation of the sites with P. reticulatus, T. indica, and A. occidentale plant species should be attempted before earthworm introduction. The litter from these species acts as a source of food for earthworms, thereby hastening the process of restoration of abandoned iron ore mines of Goa, India.

Notes: Abstract River and stream rehabilitation projects are increasing in number, but the success or failure of these projects has rarely been evaluated, and the extent to which buffers can restore riparian and stream function and species composition is not well understood. In New Zealand the widespread conversion of forest to agricultural land has caused degradation of streams and riparian ecosystems. We assessed nine riparian buffer zone schemes in North Island, New Zealand that had been fenced and planted (age range from 2 to 24 years) and compared them with unbuffered control reaches upstream or nearby. Macroinvertebrate community composition was our prime indicator of water and habitat quality and ecological functioning, but we also assessed a range of physical and water quality variables within the stream and in the riparian zone. Generally, streams within buffer zones showed rapid improvements in visual water clarity and channel stability, but nutrient and fecal contamination responses were variable. Significant changes in macroinvertebrate communities toward “clean water” or native forest communities did not occur at most of the study sites. Improvement in invertebrate communities appeared to be most strongly linked to decreases in water temperature, suggesting that restoration of in-stream communities would only be achieved after canopy closure, with long buffer lengths, and protection of headwater tributaries. Expectations of riparian restoration efforts should be tempered by (1) time scales and (2) spatial arrangement of planted reaches, either within a catchment or with consideration of their proximity to source areas of recolonists.

Notes: Abstract One of the greatest challenges for ecologists this century will be restoring forests on degraded tropical lands. This restoration will require understanding complex processes that shape successional pathways, including interactions between trees and other plants. Shrub species often quickly invade disturbed tropical lands, yet little is known about whether they facilitate or inhibit subsequent tree recruitment and growth. We examined how shrubs and other vegetation (e.g., vines, grasses, herbs) affect tree recruitment, survival, and growth during the first 6 years of forest succession in Kibale National Park, Uganda. The study was undertaken in two recently logged exotic softwood plantations. We studied the successional trajectories in two recently logged areas that varied in their initial densities of trees and shrubs. Analyses suggested tree seedling presence and density were not strongly related to shrub density or height during succession. Tree sapling presence and density were positively significantly related to shrub density and height. We found little response in the tree community to experimental shrub removal, and although removal of all nontree vegetation temporarily enhanced tree growth, the effect disappeared after 2 years. Some early-successional trees benefited from reduced competition, whereas some mid-successional trees benefited from the presence of other vegetation. Some specific tree species responded strongly to vegetation removal. We interpret our findings in light of designing manipulations promoting forest restoration for biodiversity conservation and conclude with four tentative guidelines: (1) manage at the species level, not the community level; (2) increase facilitation for seedlings, reduce competition for saplings; (3) be cautious of assumptions about plant interactions; and (4) be adaptable and creative with new strategies when manipulations fail.

Notes: Abstract Soil chemical properties and soil mesofauna composition were assessed at a forest site in northern Austria, where 20 years earlier an amelioration treatment had been performed. The site had been treated with limestone, a high P slag, and ammonium nitrate to replace the poorly growing pine (Pinus sylvestris) forest with a Norway spruce (Picea abies) stand. This treatment was at that time a common means for the amelioration of nutrient-poor forest soils with recalcitrant forest floor layers. After treatment, a dense cover of a nitrophilic stinging nettle (Urtica dioica) developed. Most likely, the site had been over-fertilized, and inadvertently, an experiment with extreme N enrichment had been conducted. The abundance of collembolans increased, and dominance structure shifted from Isotomiella minor, Lipothrix lubbocki, and Isotoma notabilis at fertilizer treatment to Friesea mirabilis, Isotomiella minor, and Sphaeridia pumilis in the control, but the abundance of soil mesofauna generally decreased in the fertilizer treatment. Fertilization reduced the mass of the litter layer from 7.6 to 2.4 kg/m2. The total carbon pool in the soil was reduced due to reduction of the litter layer. However, the content of soil organic matter in the upper mineral soil was significantly increased. A part of the applied and mineralized nitrogen had been lost from the soil, but N retention in the upper mineral soil was still considerable. Soil pH and the base saturation were sustainably increased. Carbon losses upon mineralization of the litter layer were not offset by the increase in C content of the mineral soil. Presently, the C pool in the soil of the fertilized treatment is lower than in the control. However, the overall nutrient enrichment of the soil may facilitate C sequestration in the fertilized site in the future.

Notes: Abstract Poor growth of Quercus robur L. (oak) trees has been reported on mine sites where overburden and subsoil have been used in the reinstatement of surface layers. This stunting has been attributed to a lack of macronutrients and to an adverse soil environment for root growth and mycorrhizal development. Growth, mineral nutrition, and ectomycorrhizal colonization of Q. robur seedlings were studied in an experiment carried out under controlled growing conditions in which mine spoil material was enriched with a leaf litter mulch. Enrichment of mine spoil material was found to produce a significant increase in growth and foliar N concentrations of oak seedlings. Inoculation with three taxa of ectomycorrhizal fungi did not benefit seedlings when mine spoil was the only substrate, possibly due to the poor physical properties of the unamended spoil and lack of nutrients. Inoculation with two taxa, Laccaria laccata and Hebeloma crustuliniforme, isolated from 3-year-old trees produced a significant stimulation of growth in the organically enriched treatment, which was believed to be due to greater uptake of mineralized N. However, Cortinarius anomalus isolated from fruit bodies associated with a 15-year-old tree did not increase biomass. The presence of organic matter was found to result in a significant stimulation of mycorrhizal infection by both inoculum and contaminant mycobionts. Recommendations are made for improving the establishment and growth of oak seedlings on reinstated sites.

Notes: Abstract Prairie restoration at the northern edge of the Great Plains can be frustrated by previously established non-native perennial grasses. We compared the emergence of a widely introduced grass, Agropyron cristatum, and a common native grass, Bouteloua gracilis, in a 4-year-old field experiment in which the Agropyron-dominated vegetation had either been left intact or treated annually with herbicide. This was done at two levels of water supply, reflecting conditions expected in wet and dry years, to examine the effects of among-year variability in precipitation. Water addition significantly increased the emergence of both surface-sown and buried (1 cm deep) seeds. Herbicide treatment of neighbors did not increase the emergence of experimentally added seeds. Emergence was much greater for buried (80%) than surface-sown seeds (20%). Significantly more Bouteloua than Agropyron germinated from experimentally buried seeds. Whereas only a single seedling of Bouteloua emerged from the existing seed bank, the mean density of Agropyron seedlings emerging from the seed bank was 930/m2 (range, 0 to 6,455/m2). Surprisingly, the emergence of Agropyron from the seed bank was not decreased by 4 years of herbicide treatment, possibly because herbicide may release Agropyron from intraspecific competition and allow increased seed production to compensate for decreased plant abundance. In summary, we found few differences between Agropyron and Bouteloua in spring and summer emergence at high or low water availability. The persistence of Agropyron stands despite repeated herbicide application may be partly due to increased seed production.

Notes: Abstract The effect of increasing planting unit size and stabilizing sediment was examined for two seagrass planting methods at Carnac Island, Western Australia in 1993. The staple method (sprigs) was used to transplant Amphibolis griffithii (J. M. Black) den Hartog and the plug method was used to transplant A. griffithii and Posidonia sinuosa Cambridge and Kuo. Transplant size was varied by increasing the number of rhizomes incorporated into a staple and increasing the diameter of plugs. Planting units were transplanted into bare sand, back into the original donor seagrass bed, or into a meadow of Heterozostera tasmanica, which is an important colonizing species. Sprigs of A. griffithii were extracted from a monospecific meadow; tied into bundles of 1, 2, 5, and 10 rhizomes; and planted into unvegetated areas. Half the units were surrounded by plastic mesh and the remainder were unmeshed. All treatments were lost within 99 days after transplanting, and although larger bundles survived better than smaller ones, no significant differences could be attributed to the effects of mesh or sprig size. Plugs of P. sinuosa and A. griffithii were extracted from monospecific meadows using polyvinyl chloride pipe of three diameters, 5, 10, and 15 cm, and planted into unvegetated areas nearby. Half the units were surrounded by plastic mesh and the remainder were unmeshed. Posidonia sinuosa plugs were also placed within a meadow of H. tasmanica (Martens ex Aschers.) den Hartog. Only 60% of A. griffithii plug sizes survived 350 days after transplanting back into the donor bed; however, survival of transplants at unvegetated areas varied considerably, and analysis of variance indicated a significant two-way interaction between treatment and plug size. Transplants survived better when meshed (90% survived) and survival improved with increasing plug size. Posidonia sinuosa transplants survived poorly (no plugs survived beyond 220 days in bare or meshed treatments) regardless of size. Survival of 10- and 15-cm plugs was markedly better than the 5-cm plugs in vegetated areas, including the H. tasmanica meadow. The use of large seagrass plugs may be appropriate for transplantation in high-energy wave environments.

Notes: Abstract Dominance-diversity curves have been previously constructed for a range of ecosystems around the world to illustrate the dominance of particular species and show how their relative abundances compare between communities separated in time or space. We investigate the usefulness of dominance-diversity curves in rehabilitated areas to compare the floristic composition and abundance of “undisturbed” areas with disturbed areas, using bauxite mining rehabilitation in Western Australia as an example. Rehabilitated pits (11–13 years old) subjected to prescribed fire in autumn and spring were compared with unburned rehabilitated areas and the native jarrah (Eucalyptus marginata) forest. Dominance diversity curves were constructed by ranking the log of the species density values from highest to lowest. Species were categorized according to a variety of functional responses: life form (trees, shrubs, subshrubs, and annuals), fire response syndrome (seeder or resprouter), nitrogen fixing capability, and origin (native or adventive). Exponential functions showed extremely good fits for all sites (r2 = 0.939–0.995). Dominance diversity graphs showed that after burning of rehabilitated areas, sites exhibited a more similar dominance-diversity curve than before burning. This was emphasized in a classification (UPGMA) of the regression equations from the dominance-diversity curves that showed that sites burned in spring were more similar to the native forest than sites burned in autumn. There was no significant segregation of the nitrogen-fixing and species origin categories, although the life form and fire response groupings showed significant segregation along the dominance-diversity curve. Resprouters tended to be over-represented in the lower quartiles and under-represented in the upper quartiles of post-burn sites. It is suggested that using dominance-diversity curves in the monitoring of rehabilitated areas may be a useful approach because it provides an easily interpretable visual representation of both species richness and abundance relationships and may be further utilized to emphasize categories of plants that are over- or under-represented in rehabilitated areas. This will assist in the post-rehabilitation management of these sites.

Notes: Abstract The wave-exposed nature of much of the southwestern Australian coastline considerably reduces the protective influence of seagrasses, and sediment movement appears to be relatively unaffected by their presence. Present seagrass restoration efforts focus on the deployment of large mechanically transplanted “sods” of seagrass as a means of combating the negative effects of water motion on transplant survival. The aim of this study was to investigate the combined role of wave energy and transplant spacing on sediment movement and transplant survival to provide guidance for seagrass transplantation in areas of high wave energy. One hundred sixty sods (0.25 m2) of seagrass were mechanically extracted from a mixed meadow consisting of Amphibolis griffithii (Cymodoceaceae) and Posidonia coriacea (Posidoniaceae) and planted in a high wave energy site with the treatments configured as three replicates of 16 sods placed in 4 × 4–meter squares at distances of 0.5, 1.0, and 2.0 meters apart. An additional 16 single sods were planted randomly throughout the site. Monitoring was conducted at two monthly intervals and consisted of counting the number of sods surviving and measuring the shoot density of seagrass species within each surviving sod. Sediment height was monitored using a series of sediment plates and an electronic sediment level sensor. Sod spacing had no significant effect upon transplant survival, which remained above 90% for 4 months after transplantation and then declined with the onset of winter (June to August). After 14 months individual sod survival was between 9% and 40%. Initial shoot densities were 200 to 500 shoots/m2 and declined to less than 50 shoots/m2. Sediment fluctuations up to 35 cm were noted, occasionally taking place over a matter of hours, and storms during winter caused significantly increased sediment movement. This probably curtailed rhizome extension and prevented the expansion of the transplants. This study indicates that the ability of seagrasses to influence sediment would appear to vary with the prevailing hydrodynamic regime and that a reappraisal of the notion that all seagrass communities trap sediment is necessary.

Notes: Recent events have increased awareness of the risk posed by terrorist attacks. Bacillus anthracis has resurfaced in the 21st century as a deadly agent of bioterrorism because of its potential for causing massive civilian casualties. This analysis presents the results of a computer simulation of the dispersion of anthrax spores in a typical 50-story, high-rise building after an intentional release during a bioterrorist incident. The model simulates aerosol dispersion in the case of intensive, small-scale convection, which equalizes the concentration of anthrax spores over the building volume. The model can be used to predict the time interval required for spore dispersion throughout a building after a terrorist attack in a high-rise building. The analysis reveals that an aerosol release of even a relatively small volume of anthrax spores during a terrorist incident has the potential to quickly distribute concentrations that are infectious throughout the building.

Notes: Human health risk assessments use point values to develop risk estimates and thus impart a deterministic character to risk, which, by definition, is a probability phenomenon. The risk estimates are calculated based on individuals and then, using uncertainty factors (UFs), are extrapolated to the population that is characterized by variability. Regulatory agencies have recommended the quantification of the impact of variability in risk assessments through the application of probabilistic methods.In the present study, a framework that deals with the quantitative analysis of uncertainty (U) and variability (V) in target tissue dose in the population was developed by applying probabilistic analysis to physiologically-based toxicokinetic models. The mechanistic parameters that determine kinetics were described with probability density functions (PDFs). Since each PDF depicts the frequency of occurrence of all expected values of each parameter in the population, the combined effects of multiple sources of U/V were accounted for in the estimated distribution of tissue dose in the population, and a unified (adult and child) intraspecies toxicokinetic uncertainty factor UFH-TK was determined.The results show that the proposed framework accounts effectively for U/V in population toxicokinetics. The ratio of the 95th percentile to the 50th percentile of the annual average concentration of the chemical at the target tissue organ (i.e., the UFH-TK) varies with age. The ratio is equivalent to a unified intraspecies toxicokinetic UF, and it is one of the UFs by which the NOAEL can be divided to obtain the RfC/RfD. The 10-fold intraspecies UF is intended to account for uncertainty and variability in toxicokinetics (3.2×) and toxicodynamics (3.2×). This article deals exclusively with toxicokinetic component of UF.The framework provides an alternative to the default methodology and is advantageous in that the evaluation of toxicokinetic variability is based on the distribution of the effective target tissue dose, rather than applied dose. It allows for the replacement of the default adult and children intraspecies UF with toxicokinetic data-derived values and provides accurate chemical-specific estimates for their magnitude. It shows that proper application of probability and toxicokinetic theories can reduce uncertainties when establishing exposure limits for specific compounds and provide better assurance that established limits are adequately protective. It contributes to the development of a probabilistic noncancer risk assessment framework and will ultimately lead to the unification of cancer and noncancer risk assessment methodologies.

Notes: The treatment of uncertainties associated with modeling and risk assessment has recently attracted significant attention. The methodology and guidance for dealing with parameter uncertainty have been fairly well developed and quantitative tools such as Monte Carlo modeling are often recommended. However, the issue of model uncertainty is still rarely addressed in practical applications of risk assessment. The use of several alternative models to derive a range of model outputs or risks is one of a few available techniques. This article addresses the often-overlooked issue of what we call “modeler uncertainty,” i.e., difference in problem formulation, model implementation, and parameter selection originating from subjective interpretation of the problem at hand. This study uses results from the Fruit Working Group, which was created under the International Atomic Energy Agency (IAEA) BIOMASS program (BIOsphere Modeling and ASSessment). Model-model and model-data intercomparisons reviewed in this study were conducted by the working group for a total of three different scenarios. The greatest uncertainty was found to result from modelers' interpretation of scenarios and approximations made by modelers. In scenarios that were unclear for modelers, the initial differences in model predictions were as high as seven orders of magnitude. Only after several meetings and discussions about specific assumptions did the differences in predictions by various models merge. Our study shows that parameter uncertainty (as evaluated by a probabilistic Monte Carlo assessment) may have contributed over one order of magnitude to the overall modeling uncertainty. The final model predictions ranged between one and three orders of magnitude, depending on the specific scenario. This study illustrates the importance of problem formulation and implementation of an analytic-deliberative process in risk characterization.

Notes: This article presents the results of an analysis of the accident history data reported under section 112(r) of the Clean Air Act Amendments. These data provide a fairly complete record of the consequences of reportable accidental releases occurring during the time frame 1995–1999 in the U.S. chemical industry and covering 77 toxic and 63 flammable substances subject to the provisions of section 112(r). As such, these results are of fundamental interest to the affected communities, regulators, and insurers, as well as to owners and managers in the chemical industry. The results show the statistical associations between accident frequency and severity and a number of characteristics of reporting facilities, including their size, the hazardousness of the processes and chemicals inventoried, and the regulatory programs (in addition to section 112(r)) to which these facilities are subject. The results are interpreted in light of economic drivers of protective activity and regulatory priorities for monitoring and enforcement.

Notes: Unlike other waste streams, municipal solid waste (MSW) is collected manually, and MSW collection has recently been found to be among the highest-risk occupations in the United States. However, as for other occupational groups, actual total injury rates, including the great majority of injuries not compensated and those compensated by other insurance, are not known. In this article a predictive Bayesian method of assessing total injury rates from available information without computation is presented, and used to assess the actual numbers of musculoskeletal and dermal injuries requiring clinical care of MSW workers in Florida. Closed-form predictive Bayesian distributions that narrow progressively in response to information, representing both uncertainty and variability, are presented. Available information included workers' compensation (WC) data, worker population data, and safety records for one private and one public collection agency. Subjective input comprised epidemiological and medical judgment based on a review of 165 articles. The number of injuries was assessed at 3,146 annually in Florida, or 54 ± 18 injuries per 100 workers per year with 95% confidence. Further, WC data indicate that the injury rate is 50% higher for garbage collectors specifically, indicating a rate of approximately 80 per 100 workers. Results, though subject to uncertainty in worker numbers and classification and reporting bias, agreed closely with a survey of 251 MSW collectors, of whom 75% reported being injured (and 70% reported illness) within the past 12 months. The approach is recommended for assessment of total injury rates and, where sufficient information exists, for the more difficult assessment of occupational disease rates.

Notes: Statistical fatigue life of a ductile alloy specimen is traditionally divided into three stages, namely, crack nucleation, small crack growth, and large crack growth. Crack nucleation and small crack growth show a wide variation and hence a big spread on cycles versus crack length graph. Relatively, large crack growth shows a lesser variation. Therefore, different models are fitted to the different stages of the fatigue evolution process, thus treating different stages as different phenomena. With these independent models, it is impossible to predict one phenomenon based on the information available about the other phenomenon. Experimentally, it is easier to carry out crack length measurements of large cracks compared to nucleating cracks and small cracks. Thus, it is easier to collect statistical data for large crack growth compared to the painstaking effort it would take to collect statistical data for crack nucleation and small crack growth. This article presents a fracture mechanics-based stochastic model of fatigue crack growth in ductile alloys that are commonly encountered in mechanical structures and machine components. The model has been validated by Ray (1998) for crack propagation by various statistical fatigue data. Based on the model, this article proposes a technique to predict statistical information of fatigue crack nucleation and small crack growth properties that uses the statistical properties of large crack growth under constant amplitude stress excitation. The statistical properties of large crack growth under constant amplitude stress excitation can be obtained via experiments.

Notes: An occupational risk assessment for manganese (Mn) was performed based on benchmark dose analysis of data from two epidemiological studies providing dose-response information regarding the potential neurological effects of exposure to airborne Mn below the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Level (PEL) of 5 mg Mn/m3. Based on a review of the scientific evidence regarding the toxicity of Mn, it was determined that the most appropriate measure of exposure to airborne Mn for the subclinical effects measured in these studies is recent (rather than historical or cumulative) concentration of Mn in respirable (rather than total) particulate. For each of the studies analyzed, the individual exposure and response data from the original study had been made available by the investigators. From these two studies benchmark concentrations calculated for eight endpoints ranged from 0.09 to 0.27 mg Mn/m3. From our evaluation of these results, and considering the fact that the subtle, subclinical effects represented by the neurological endpoints tested in these studies do not represent material impairment, we believe an appropriate occupational exposure guideline for manganese would be in the range of 0.1 to 0.3 mg Mn/m3, based on the respirable particulate fraction only, and expressed as an 8-hour time-weighted average.

Notes: The Safe Drinking Water Act Amendments of 1996 required U.S. utilities to report on drinking water quality to their customers annually, beginning in fall 1999, on the assumption that such reports would alert them to quality problems and perhaps mobilize pressure for improvement. A random sample of New Jersey customers read alternative versions of a water quality report, in an experiment on reactions to water quality information under U.S. Environmental Protection Agency (USEPA) rules. Experiment design was 2 × 3 + 1: two versions each—one with, one without, a violation of a health standard—of a report that was (1) Qualitative (without water quality numbers, thus not meeting USEPA rules); (2) Basic, with minimal information meeting the rules; or (3) Extended, adding reading aids and utility performance information; plus a control instrument without any hypothetical report. Results of ANOVA suggest the reports will have less effect than hoped or feared. These manipulations were successful: people reading the Qualitative versions were less likely to say that the report gave the amounts of substances found in the water, and those reading Violation versions were more likely to report a violation of a health standard. The main differences in responses to the report involved the judged adequacy of the information, and to a lesser extent responses on a Concern scale (constructed from measures of concern, judged risk, clean-up intentions, distrust of utility information, and doubt that the utility was doing all it could to improve water quality). Overall judgments of water quality and utility performance did not change, either relative to the controls or in before versus after responses. Qualitative reports performed worse than others, confirming the decision to have utilities report actual contaminant levels. Extended reports did only slightly better than the Basic versions on these measures. Many respondents had trouble identifying the presence or absence of substance amounts or violations, despite their seeming obviousness (e.g., in a “bottom line” summary on the front page of each report), suggesting many were not processing this information carefully. However, the pattern of responses for those who accurately identified the presence or absence of substance amounts or violations did not differ substantially from that for the group as a whole. Generic risk beliefs (serious local environmental problems; lack of control over risks to one's health) dominated demographic variables, attitudes toward utility water quality or trustworthiness, and the content and format of water quality reports in influencing concern about drinking water quality. Previous empirical and theoretical evidence for lack of change in public risk attitudes due to one-time or infrequent communications—e.g., role of personal experience, perseverance of prior trust or distrust—seems to be confirmed for annual water quality reports.

Notes: Polluted soils have become a public health problem. While population exposure to soil pollutants is generally quantified using multimedia models, their estimations have not been validated, and studies that attempted to do so are scarce. The objective of the SOLEX study was to compare the predictions of pyrene exposure levels (converted into 1 hydroxypyrene) computed by several models with the results of urinary 1-hydropyrene (1-HOP) assays among 110 employees working at three sites polluted during their past use as manufactured gas plants. Four models were used: AERIS (Canada), CalTOX (California, USA), CLEA (UK), and HESP (The Netherlands). Three occupational exposure scenarios—with office, mixed, and outdoor workers—were constructed, based upon job activities during two measurement campaigns, one in winter and one in summer. The exposure levels estimated by the four models could differ markedly (from 7 up to 80 times) according to the exposure scenario. Also, the predominant exposure routes differed according to the model (direct soil ingestion for HESP and CalTOX, inhalation for AERIS, and dermal absorption for CLEA). The predictions of CalTOX are consistent with the 1-HOP measurements for all the scenarios. For HESP, the consistency is observed for the scenarios, office and mixed, for which the pyrene level in the soil is low. AERIS and CLEA yield results that are systematically above the 1-HOP measurements. This study confirms that validation of the models is crucial and points out to the need to proceed to assess components of the models that are the most influential using appropriate statistical analysis in combination with true field data.

Notes: The wide-scale use of methyl tertiary butyl ether (MTBE) in gasoline has resulted in substantial public controversy and action to ban or control its use due to perceived impacts on water quality. Because oxygenates are still required under federal law, considerable research has focused on ethanol as a substitute for MTBE. In this article, we summarize the currently available literature on the air and water quality risks and benefits of MTBE versus ethanol as alternative fuel oxygenates. We find that MTBE-fuel blends are likely to have substantial air quality benefits; ethanol-fuel blends appear to offer similar benefits, but these may be at least partially negated because of ethanol's propensity to increase emissions and ambient concentrations of some air contaminants. Releases of gasoline containing either MTBE or ethanol could have an impact on some drinking water sources, although the impacts associated with MTBE tend to relate to aesthetics (i.e., taste and odor), whereas the impacts associated with ethanol generally relate to health risk (i.e., greater exposure to gasoline constituents such as benzene). It is likely that these water quality impacts will be outweighed by the air quality benefits associated with MTBE and perhaps ethanol use, which affect a much larger population. A lack of data on environmental exposures and associated health impacts hinders the completion of a comprehensive quantitative risk-benefit analysis, and the available air and water quality data should be evaluated in a broader risk-management context, which considers the potential life-cycle impacts, costs, and feasibility associated with alternative fuel oxygenates.

Notes: A sample of 3,201 Danes was subjected to personal interviews in which they were asked to state their preferences for risk-reducing health care interventions based on information on absolute risk reduction (ARR) and relative risk reduction (RRR). The aim of the study was to measure the relative weighting of different types of risk information under various circumstances. The effect of presenting questions, and of explicitly formulating RRR, was analyzed. A preference for increases in RRR was demonstrated. There was a stronger inclination to choose the intervention that offered the highest RRR if RRR was explicitly stated. Individuals with more than 10 years of schooling also demonstrated a preference for increased ARR, but only when facing individually framed choices. In a social choice context, preferences for RRR remained intact, but the magnitude of ARR had no impact on choices. Results imply that social framing may induce a propensity to prefer interventions that target high-risk populations. Those respondents who had received ≤10 years of schooling demonstrated preferences for RRR but not ARR, and no impact of social framing was observed.

Notes: The relationship between trust and risk perception was investigated, within and across four European countries (Sweden, Spain, United Kingdom, and France). Survey data were collected in 1996; total number of respondents was approximately 1,000 (United Kingdom and Spain), 1,350 (France), and 2,050 (Sweden). Trust was a significant predictor of perceived risk within countries, but the strength of the relationship varied from weak (Spain and France) to moderate (United Kingdom and Sweden). General trust was also a significant source of variation in perceived risk among countries, but much of the variation in perceived risk remained unexplained. Correlations between trust and risk perception also varied depending on the type of risk (i.e., nuclear risks were more influenced by trust) and trust measure (i.e., general trust explained perceived risk better than specific trust). It is concluded that trust may be an element in models explaining risk perception, but it is not as powerful as often argued in the risk perception literature.

Notes: Despite many claims for and against the use of risk comparisons in risk communication, few empirical studies have explored their effect. Only one study, published by Roth et al. in this journal in 1990, has tested the 1988 predictions by Covello et al. as to the public's relative preferences for 14 kinds of risk comparisons as they might be used by a factory manager to explain risks of his ethylene oxide plant. That study found no correlations between the Covello predictions and seven different measures of “acceptability” of Covello's examples of each type of comparison. However, two critics of the Roth study, as well as its own authors, suggested that a scenario involving local risks, a conflict-ridden situation, and a plant manager unknown to the townspeople might better evoke Covello-like preferences than the distant, calm, friends-involving scenario used by Roth. The research reported here replicated the Roth study using the same scenario, risk comparison examples, and evaluation measures, and added a second scenario intended to replicate the conditions suggested by critics. Over 200 New Jersey residents answered the study questionnaire. The replication scenario reproduced Roth's results, and the conflict scenario also evoked no rankings correlated with Covello's predictions. Furthermore, neither agreement nor disagreement with five statements representing “conflict”—respondents' reports that the industrial-plant scenario made them angry, they lived near industry, they were concerned about industrial risks, people in their home town were angry about industrial pollution, and they worried “frequently” about long-term effects of pollution—correlated with Covello's predictions. Over half of all ratings ascribed to the comparisons in aggregate were positive, and most detailed comments offered by respondents also were positive, despite many criticisms and suggestions for their improvement. The wide variability in individuals' rankings also undermines the notion of any single ranking of preferred comparisons. These findings have implications for use of risk comparisons, but also reveal the inaccuracy of the field's assumptions about public reaction to industrial risk information, including risk comparison.

Notes: The effect of specification of the target on risk evaluation was examined. A whole set of hazards, covering most of the domains, were considered: common individual hazards, outdoor activities, medical care, public transportation, energy production, pollutants, sex, deviance, and addictions. Three human targets were introduced: personal health risk (including personal risk of death), health risk for people in the country, and health risk for people in the world. The basic design was a between-subjects design. The first hypothesis was that risk judgments made in the “world” condition should be higher than risk judgments made in the “country” condition, and risk judgments made in this condition should be higher than risk judgments made in the “personal” condition. This is what was observed. The second hypothesis was that the target effect should differ as a function of the kind of hazards considered. This also is what was observed. In two domains— pollutants, and deviance, sex, and addictions—the target effect was important. It corresponded to about one-tenth of the response scale. In the four remaining domains, the target effect was unimportant or absent.

Notes: Dissemination of risk information is ubiquitous in contemporary society. We explore how individuals react in everyday life to health-risk information, based on what they report in personal interviews. Health-risk information was without exception recognized as unstable and inconsistent. This conformity, however, did not extend to the narratives regarding how health-risk information should be handled. Two opposite positions (ideal-typical strategies) are presented. Either you tend to process and evaluate new information or you tend to ignore it as a whole. Our attempt to reveal the underlying rationality in these two very different approaches involved the exploration of three different avenues of interpretation and brings together two scientific paradigms—economics and sociology—that provide the framework for our analysis. First, we suggest that a greater long-term experience of explicit choice implies that this kind of action becomes more natural and less resource consuming, whereas a reliance on habits in daily life—a natural adjustment to a lack of resources—makes it is more costly to bother about new information. Second, with fewer resources in the short run, fewer opportunities to mitigate bad outcomes, and greater exposure to social and material risks, one is less likely to devote resources to deal with health-risk information. Third, there are several possible links between a low propensity to take account of risk information and a high relative importance of genuine uncertainty in one's life. These theoretical perspectives provide a viable set of hypotheses regarding mechanisms that may contribute to social differences in the response to health-risk information.

Notes: European directives require that all veterinary medicines be assessed to determine the harmful effects that their use may have on the environment. Fundamental to this assessment is the calculation of the predicted environmental concentration (PEC), which is dependent on the type of drug, its associated treatment characteristics, and the route by which residues enter the environment. Deterministic models for the calculation of the PEC have previously been presented. In this article, the inclusion of variability and uncertainty within such models is introduced. In particular, models for the calculation of the PEC for residues excreted directly onto pasture by grazing animals are considered and comparison of deterministic and stochastic results suggest that uncertainty and variability cannot be ignored.

Notes: In risk assessment, no observed exposure level (NOAEL) and benchmark dose (BMD) are usually derived either from epidemiological studies in humans or from animal experiments. In many in vitro studies, concentration-effect/response curves have been analyzed using different mathematical models finalized to the identification of EC50. In the present article, we propose a model to fit dose-response curves in vitro. The BMD approach has been used to compare the cell viability (MTT assay) of different rat (C6 and PC12, glial and neuronal, respectively) and human cell lines (D384 and SK-N-MC, glial and neuronal, respectively) after 24-hour exposure to the following neurotoxic substances: manganese chloride (MnCl2), methyl-mercury (Me-Hg), and the enantiomers of styrene oxide (SO). For all rat and human cell lines, the potency of the examined compounds was: MnCl2 〈 S-SO 〈 R-SO 〈 Me-Hg. A preliminary comparison with in vivo toxicity data for these substances gave rise to consistent results. Whereas a reasonable agreement between in vitro and in vivo data has been found for Mn and styrene oxide, a wide scatter of LOAEL has been reported for Me-Hg and these appear to be either much higher or lower than the BMD for the MTT assay we observed invitro.

Notes: This article examines the role of climatic and hydrological variability in assessing the cumulative risk of flood events in Poland over a T-year period. In a broad sense flood-risk estimation combines a frequency analysis of extreme hydrological phenomena with an evaluation of flood-induced damages. The damage from floods depends on the critical values of the river discharges. The probabilistic flood analysis usually includes an estimation of the expected annual probability of the critical discharge Qcr being exceeded and the equivalent long-term risk of it being exceeded over the next T years. If, however, the process is nonstationary, the T-year risk of flood damage may depend importantly on the variation of hydrological processes. As a possible explanation for the variations observed in snowmelt-induced floods in Polish rivers, this article investigates the possible impact of the North Atlantic Oscillation (NAO) on surface air temperature T and precipitation P. The spatial distribution of the correlation coefficients between NAO and T, as well as NAO and P, show very significant differences in the NAO impact on meteorological variables in various parts of Europe. To assess the implications of NAO variations on spring flood discharges, a simple model of Snow Cover Water Equivalent (SCWE) was applied to selected Polish river catchments. The conclusion of this analysis is that the yearly maximum of SCWE values significantly decreases with increasing NAO. This leads to a temporal redistribution of winter and spring runoff. The question of spring flood characteristics being stationary or nonstationary may therefore be linked with stochastic properties of the NAO index time series.

Notes: We examine the opportunities for using catastrophe-linked securities (or equivalent forms of nondebt contingent capital) to reduce the total costs of funding infrastructure projects in emerging economies. Our objective is to elaborate on methods to reduce the necessity for unanticipated (emergency) project funding immediately after a natural disaster. We also place the existing explanations of sovereign-level contingent capital into a catastrophic risk management framework. In doing so, we address the following questions. (1) Why might catastrophe-linked securities be useful to a sovereign nation, over and above their usefulness for insurers and reinsurers? (2) Why are such financial instruments ideally suited for protecting infrastructure projects in emerging economies, under third-party sponsorship, from low-probability, high-consequence events that occur as a result of natural disasters? (3) How can the willingness to pay of a sovereign government in an emerging economy (or its external project sponsor), who values timely completion of infrastructure projects, for such instruments be calculated? To supplement our treatment of these questions, we use a multilayer spreadsheet-based model (in Microsoft Excel format) to calculate the overall cost reductions possible through the judicious use of catastrophe-based financial tools. We also report on numerical comparative statics on the value of contingent-capital financing to avoid project disruption based on varying costs of capital, probability and consequences of disasters, the feasibility of strategies for mid-stage project abandonment, and the timing of capital commitments to the infrastructure investment. We use these results to identify high-priority applications of catastrophe-linked securities so that maximal protection can be realized if the total number of catastrophe instruments is initially limited. The article concludes with potential extensions to our model and opportunities for future research.

Notes: Risk perceptions have, to a great extent, been studied exclusively as individual cognitive mechanisms in which individuals collect, process, and form perceptions as atomized units unconnected to a social system. These individual-level theories do not, however, help explain how perception of risk may vary between communities or within a single community. One alternative approach is based on a network theory of contagion. This approach, emerging largely from organizational and community social network studies, suggests that it is the relational aspects of individuals and the resulting networks and self-organizing systems that influence individual perceptions and build “groups or communities of like-minded” individuals. These social units, it is argued, behave as attitude, knowledge, or behavioral structures. The study reported in this article tests one aspect of this theoretical perspective. The central hypothesis proposes the existence of risk perception networks—relational groupings of individuals who share, and perhaps create, similar risk perceptions. To test this idea, data were collected from individuals involved in a community environmental conflict over a hazardous waste site cleanup. The statistical analysis used a matrix of relational social linkages to compare with a matrix of individual risk perceptions. The analysis confirmed the hypothesis suggesting that social linkages in communities may play an important role in focusing risk perceptions.

Notes: We adopted a comparative approach to evaluate and extend a generic methodology to analyze the different sets of beliefs held about chemical hazards in the workplace. Our study mapped existing knowledge structures about the risks associated with the use of perchloroethylene and rosin-based solder flux in differing workplaces. “Influence diagrams” were used to represent beliefs held by chemical experts; “user models” were developed from data elicited from open-ended interviews with the workplace users of the chemicals. The juxtaposition of expert and user understandings of chemical risks enabled us to identify knowledge gaps and misunderstandings and to reinforce appropriate sets of safety beliefs and behavior relevant to chemical risk communications. By designing safety information to be more relevant to the workplace context of users, we believe that employers and employees may gain improved knowledge about chemical hazards in the workplace, such that better chemical risk management, self-protection, and informed decision making develop over time.

Notes: Seven driving attitude scales representing driving behaviors and beliefs about driving were created and initially validated using 257 undergraduate students (168 females, 89 males) in Study 1. However, the Speeding Attitude Scale (SAS) accounted for most of the strength of the intercorrelations among these scales and discriminant classification analyses showed that SAS dominated the other scales as a sufficient explanation for having speeding tickets. Study 2, using 180 students (75 males, 105 females), replicated findings regarding the significant but low correlation between SAS and speeding tickets, and was significantly correlated with Zuckerman's Sensation Seeking Scale (SSS). Replication also showed that males had higher SAS scores and more speeding tickets. Accidents were typically a function of sex, increasing age, and variables related to recent accident history. Objective sources of speeding attitude confirmation may enhance the future validity of the SAS. Potential interventions for being a safe passenger and attitudinal control in the training of young drivers were discussed.

Notes: The prospect of industrial accidents motivated the U.S. Congress to require in the Clean Air Act of 1990 that manufacturing facilities develop Risk Management Plans (RMP) to submit to the U.S. Environmental Protection Agency (USEPA) by July 1999. Industry worried that the requirement to communicate to the public a “worst-case scenario” would arouse unnecessary and counterproductive fears among industry neighbors. We report here the results of focus groups and surveys with such neighbors, focusing particularly upon their reactions to messages about a hypothetical worst-case scenario and management of these risks by industry, government, and other parties. Our findings confirmed our hypotheses that citizens would be skeptical of the competence and trustworthiness of these managers and that this stance would color their views of industrial-facility accident risks. People with job ties to industry or who saw industrial benefits to the community as exceeding its risks had more positive views of industrial risks, but still expressed great concern about the risk and doubt about accident management. Notwithstanding these reactions, overall respondents welcomed this and other related information, which they wanted their local industries to supply. Respondents were not more reassured by additional text describing management of accidents by government and industry. However, respondents did react very positively to the concept of community oversight to review plant safety. Claims about the firm's moral obligation or financial self-interest in preventing accidents were also received positively. Further research on innovative communication and management of accident risks is warranted by these results, even before recent terrorist attacks made this topic more salient.

Notes: Enabling people to make an informed choice on whether to change consumption behavior is ultimately the objective of any fish consumption advisory. This will occur only if people are aware of the advisory, know and understand the advisory information, and believe the information to be true. Interactive, meaningful communication and the opportunity to participate in the process to develop and review advisories are key to achieving these attributes. A case study was undertaken in a community in Alberta, Canada (where an existing advisory was under consideration for review) to determine public awareness, knowledge, compliance, communication effectiveness, information needs, and desire for involvement related to the advisory. The information obtained from this case study was used to develop 14 guiding principles as a foundation for the incorporation of public participation and risk communication into the process of developing and reviewing fish consumption advisories.

Notes: The impacts of fish consumption advisories on recreational and subsistence fishing, particularly in fresh waters, have been examined extensively. By contrast, little attention has focused on organized recreational fishing, such as from party and charter boats, and particularly for salt water fish. We interviewed 93 New Jersey boat captains to determine their knowledge about fish consumption advisories, and whether, in their opinion, clients knew of fish consumption advisories, and whether they thought advisories had an effect on recreational fishing and their businesses. Advisories were ranked by captains as a moderate influence on the success of their business, less so than number of fish caught, strength of the economy, overfishing by commercial boats, and management regulations. Only one boat captain had not heard warnings about eating fish, but what captains said they had heard was mixed in its accuracy and completeness. Clients expect captains to know about fish, and about half of boat captains said clients had asked about the safety of eating fish. Captains who felt advisories were affecting their businesses tended to fish for species without high levels of mercury (except for bluefish) or PCBs, the primary contaminants of concern for state advisories and federal advice. However, these captains worked closer to areas (e.g., Raritan Bay complex and New York Harbor) subject to advisories than did other captains, and were more prone to say that management regulations (e.g., fish size, creel limits, seasons) and marketing and advertising by the industry or state were strong influences on the success of their seasons. Comparing captains who thought advisories had some or great effect (60%) versus those reporting “no effect” (40%), there was no difference in the mean percentage of trips targeting high mercury species such as swordfish and shark. Many captains said they would or might post advisories, but 42% of the boat captains said they would not post consumption warnings if the state provided them. The significant portion (at least 15%) of saltwater fishing supported by these businesses suggests that these captains are an important conduit for future risk communication.

Notes: This article begins with a review of the regulation of chemicals in Sweden over the past 30 years, focusing particularly on the 1997 Government Environmental Quality Bill, which called for a toxic-free society by the year 2020. The second part of the article analyzes why Sweden has taken this route. The third and final section discusses Sweden's present role in formulating present EU chemical regulation, such as the recent EU Chemical White Paper, and hypothesizes future impacts of Swedish chemical regulations on the EU itself.

Notes: In 2001, the U.S. Environmental Protection Agency derived a reference dose (RfD) for methylmercury, which is a daily intake that is likely to be without appreciable risk of deleterious effects during a lifetime. This derivation used a series of benchmark dose (BMD) analyses provided by a National Research Council (NRC) panel convened to assess the health effects of methylmercury. Analyses were performed for a number of endpoints from three large longitudinal cohort studies of the neuropsychological consequences of in utero exposure to methylmercury: the Faroe Islands, Seychelles Islands, and New Zealand studies. Adverse effects were identified in the Faroe Islands and New Zealand studies, but not in the Seychelles Islands. The NRC also performed an integrative analysis of all three studies. The EPA applied a total uncertainty factor (UF) of 10 for intrahuman toxicokinetic and toxicodynamic variability and uncertainty. Dose conversion from cord blood mercury concentrations to maternal methylmercury intake was performed using a one-compartment model. Derivation of potential RfDs from a number of endpoints from the Faroe Islands study converged on 0.1 μg/kg/day, as did the integrative analysis of all three studies. EPA identified several areas for which further information or analyses is needed. Perhaps the most immediately relevant is the ratio of cord:maternal blood mercury concentration, as well as the variability around this ratio. EPA assumed in its dose conversion that the ratio was 1.0; however, available data suggest it is perhaps 1.5–2.0. Verification of a deviation from unity presumably would be translated directly into comparable reduction in the RfD. Other areas that EPA identified as significant areas requiring further attention are cardiovascular consequences of methylmercury exposure and delayed neurotoxicity during aging as a result of previous developmental or adult exposure.

Notes: Risk estimates for food-borne infection will usually depend heavily on numbers of microorganisms present on the food at the time of consumption. As these data are seldom available directly, attention has turned to predictive microbiology as a means of inferring exposure at consumption. Codex guidelines recommend that microbiological risk assessment should explicitly consider the dynamics of microbiological growth, survival, and death in foods. This article describes predictive models and resources for modeling microbial growth in foods, and their utility and limitations in food safety risk assessment. We also aim to identify tools, data, and knowledge sources, and to provide an understanding of the microbial ecology of foods so that users can recognize model limits, avoid modeling unrealistic scenarios, and thus be able to appreciate the levels of confidence they can have in the outputs of predictive microbiology models. The microbial ecology of foods is complex. Developing reliable risk assessments involving microbial growth in foods will require the skills of both microbial ecologists and mathematical modelers. Simplifying assumptions will need to be made, but because of the potential for apparently small errors in growth rate to translate into very large errors in the estimate of risk, the validity of those assumptions should be carefully assessed. Quantitative estimates of absolute microbial risk within narrow confidence intervals do not yet appear to be possible. Nevertheless, the expression of microbial ecology knowledge in “predictive microbiology” models does allow decision support using the tools of risk assessment.

Notes: Zircon from a lower crustal metapelitic granulite (Val Malenco, N-Italy) display inherited cores, and three metamorphic overgrowths with ages of 281 ± 2, 269 ± 3 and 258 ± 4 Ma. Using mineral inclusions in zircon and garnet and their rare earth element characteristics it is possible to relate the ages to distinct stages of granulite facies metamorphism. The first zircon overgrowth formed during prograde fluid-absent partial melting of muscovite and biotite apparently caused by the intrusion of a Permian gabbro complex. The second metamorphic zircon grew after formation of peak garnet, during cooling from 850 °C to c. 700 °C. It crystallized from partial melts that were depleted in heavy rare earth elements because of previous, extensive garnet crystallization. A second stage of partial melting is documented in new growth of garnet and produced the third metamorphic zircon. The ages obtained indicate that the granulite facies metamorphism lasted for about 20 Myr and was related to two phases of partial melting producing strongly restitic metapelites.Monazite records three metamorphic stages at 279 ± 5, 270 ± 5 and 257 ± 4 Ma, indicating that formation ages can be obtained in monazite that underwent even granulite facies conditions. However, monazite displays less clear relationships between growth zones and mineral inclusions than zircon, hampering the correlation of age to metamorphism. To overcome this problem garnet–monazite trace element partitioning was determined for the first time, which can be used in future studies to relate monazite formation to garnet growth.

Notes: A suite of spinel–cordierite granulites from Viziangram, Eastern Ghats Belt, India preserve mineral assemblages and reaction textures indicative of peak metamorphic conditions of 〉1000 °C, 〉8〈10 kbar, followed successively by near isobaric cooling (down to 750–800 °C), near isothermal decompression (to 4–5 kbar), and late hydration. P–T conditions of each stage are evaluated through a combination of petrogenetic grid approach and thermobarometry. Sapphirine is developed in sillimanite-bearing acid pegmatite veins that intruded the spinel–cordierite granulite close to peak metamorphic conditions, and also in the host rock in immediate contact with the pegmatite. Both sillimanite and sapphirine in the pegmatite are considered to be magmatic phases. Field observations and textural characteristics suggest that Al-metasomatism of the spinel–cordierite granulite due to the intrusion of pegmatite was responsible for sapphirine formation in the spinel granulite.

Notes: Whereas geologists have known for three-quarters of a century that there was significant crustal thickening in the central East Greenland Caledonides, the crucial role of extensional faulting during Caledonian orogenesis has only been recognized during the past decade. In this paper, new petrographic and thermobarometric observations are presented from migmatitic metasedimentary gneisses of the Forsblad Fjord region (c. 72.5°N). Samples of the Krummedal Sequence, collected from the footwall of the upper of two significant splays of the main extensional fault system in the region—the Fjord Region Detachment (FRD)—enable us to establish a relative sequence of metamorphism. Our pressure (P)–temperature (T) results imply a clockwise loop in P–T space. As recorded by mineral assemblages in the Krummedal gneisses, prograde metamorphism involved a net increase of c. 4 kbar and 250 °C, with peak conditions of c. 10.5 kbar at 785 °C. Early burial and heating was followed by near-isothermal decompression of 4.5 kbar, a process which is attributed to roughly 18 km of tectonostratigraphic throw on the upper splay of the FRD. Combining data reported here with the published data, it is estimated that the approximate tectonostratigraphic throw along the lower splay of the FRD was c. 16 km. In situ U–Th–Pb-monazite electron microprobe dating suggests that the earliest phase of metamorphism recorded in the Krummedal Sequence gneisses of Forsblad Fjord occurred during the Caledonian orogeny. Furthermore, the combination of our new data with existing conventional TIMS U-Pb and 40Ar/39Ar data imply that: (1) movement along the uppermost splay of the FRD (c. 425–423 Ma) occurred at maximum time-averaged slip-rates equivalent to c. 9 mm of vertical displacement per year; and (2) that the final stages of metamorphism occurred prior to c. 411 Ma, although part of this denudation was likely accommodated on overlying extensional structures that may have been active more recently. There is close agreement between our data and results from the Krummedal Sequence north of the field area (72.5°−74°N), and rocks of the Smallefjord Sequence (75°−76°N) that are suggested to correlate with the Krummedal Sequence. This leads us to infer that the events recorded in the Forsblad Fjord region are of orogen-scale significance.

Notes: New data on the metamorphic petrology and zircon geochronology of high-grade rocks in the central Mozambique Belt (MB) of Tanzania show that this part of the orogen consists of Archean and Palaeoproterozoic material that was structurally reworked during the Pan-African event. The metamorphic rocks are characterized by a clockwise P–T path, followed by strong decompression, and the time of peak granulite facies metamorphism is similar to other granulite terranes in Tanzania. The predominant rock types are mafic to intermediate granulites, migmatites, granitoid orthogneisses and kyanite/sillimanite-bearing metapelites. The meta-granitoid rocks are of calc-alkaline composition, range in age from late Archean to Neoproterozoic, and their protoliths were probably derived from magmatic arcs during collisional processes. Mafic to intermediate granulites consist of the mineral assemblage garnet–clinopyroxene–plagioclase–quartz–biotite–amphibole ± K-feldspar ± orthopyroxene ± oxides. Metapelites are composed of garnet-biotite-plagioclase ± K-feldspar ± kyanite/sillimanite ± oxides. Estimated values for peak granulite facies metamorphism are 12–13 kbar and 750–800 °C. Pressures of 5–8 kbar and temperatures of 550–700 °C characterize subsequent retrogression to amphibolite facies conditions. Evidence for a clockwise P–T path is provided by late growth of sillimanite after kyanite in metapelites. Zircon ages indicate that most of the central part of the MB in Tanzania consists of reworked ancient crust as shown by Archean (c. 2970–2500 Ma) and Palaeoproterozoic (c. 2124–1837 Ma) protolith ages. Metamorphic zircon from metapelites and granitoid orthogneisses yielded ages of c. 640 Ma which are considered to date peak regional granulite facies metamorphism during the Pan-African orogenic event. However, the available zircon ages for the entire MB in East Africa and Madagascar also document that peak metamorphic conditions were reached at different times in different places. Large parts of the MB in central Tanzania consist of Archean and Palaeoproterozoic material that was reworked during the Pan-African event and that may have been part of the Tanzania Craton and Usagaran domain farther to the west.

Notes: Abstract An analytical electron microscope study of almandine garnet from a metamorphosed Al–Fe-rich rock revealed detailed composition profiles and defect microstructures of resorption zoning along fluid-infiltrated veins and even into the garnet/ilmenite (inclusion) interface. This indicates a limited volume diffusion for the cations in substitution (mainly Ca and Fe) and an interface-controlled partition for the extension of a composition-invariant margin. A corrugated interface between the Ca-rich margin/zone and the almandine garnet core is characterized by dislocation arrays and recovery texture further suggesting a resorption process facilitated by diffusion-induced recrystallization, diffusion-induced dislocation migration and diffusion–induced grain boundary migration. Integrated microstructural and chemical studies are essential for understanding the underlying mechanisms of processes such as garnet zoning and its modification. Without this understanding, it will not be possible to reliably use garnet compositions for thermobarometry and other applications that rely on garnet chemical information.

Notes: Abstract Granulite facies metapelites of the Mather and Filla Paragneisses within the Rauer Group, east Antarctica, possess markedly different compositions. The metamorphic evolution of the two metapelite types has been interpreted as temporally distinct, with the Rauer Group preserving at least two distinct granulite facies tectonothermal episodes. Calculated P–T pseudosections and orthopyroxene Al content indicate the revised maximum-preserved P–T conditions within the Mather Paragneiss to lie in the vicinity of 950–975 °C and 10–10.6 kbar, less extreme than previous estimates. The range of possible P–T paths for the Mather Paragneiss consistent with mineral textural relationships and pseudosections contoured for mineral proportion are significantly shallower (dP/dT) than previous estimates. A near-isothermal decompression P–T path, and extreme peak metamorphic conditions, are not necessary to explain the development of preserved mineral reaction textures. The Filla Paragneiss contains pelitic assemblages less amenable to rigorous quantitative analysis. Nevertheless, possibilities for the shared or otherwise metamorphic evolution of the Mather and Filla Paragneisses may be postulated on the basis of calculated pseudosections in the context of existing geochronology for the Rauer Group and preserved microstructures. A shared evolution, most likely during Pan-African granulite facies metamorphism, is plausible and consistent with mineral assemblage development, geochronology and microstructures. A revised interpretation of the Rauer Group's preserved metamorphic evolution may warrant the revision of existing tectonic models, applicable also to the remainder of Prydz Bay. More generally, the employed approach may incite a revision of peak P–T and P–T paths in other granulite facies terranes.

Notes: The solid-state reaction magnesite (MgCO3) + calcite (aragonite) (CaCO3) = dolomite (CaMg(CO3)2) has been identified in metapelites from western Tianshan, China. Petrological studies show that two metamorphic stages are recorded in the metapelites: (1) the peak mineral assemblage of magnesite and calcite pseudomorphs after aragonite which is only preserved as inclusions within dolomite; and (2) the retrograde glaucophane-chloritoid facies mineral assemblage of glaucophane, chloritoid, dolomite, garnet, paragonite, chlorite and quartz. The peak metamorphic temperatures and pressures are calculated to be 560–600 °C, 4.95–5.07 GPa based on the calcite–dolomite geothermometer and the equilibrium calculation of the reaction dolomite = magnesite + aragonite, respectively. These give direct evidence in UHP metamorphic rocks from Tianshan, China, that carbonate sediments were subducted to greater than 150 km depth. This UHP metamorphism represents a geotherm lower than any previously estimated for subduction metamorphism (〈 3.7 °C km−1) and is within what was previously considered a ‘forbidden’ condition within Earth. In terms of the carbon cycle, this demonstrates that carbonate sediments can be subducted to at least 150 km depth without releasing significant CO2 to the overlying mantle wedge.

Notes: Field data define two lithologically distinct basement-cover sequences within the ultrahigh-pressure metamorphic (UHPM) unit of the Dabie Shan, eastern China. One of the cover units, the Changpu unit, comprises calc-arenitic metasediments in stratigraphic contact with a basement consisting of gneisses of the Yangtze craton. The second cover unit, the Ganghe unit, consists of felsic-intermediate metavolcanics and clastic metasediments. Basement exposure of the Ganghe unit is not known. Fold axes in the Ganghe unit are oblique to those of the Changpu unit, which are parallel to those of the Yangtze gneisses. Preservation of primary textures in some volcanic rocks, and tectonic separation from the Yangtze gneisses by a greenschist facies mylonite, support an interpretation of the Ganghe unit as a low-strain domain. Protolith associations in the Ganghe and Changpu units are compatible with deposition in a rift setting and along a passive continental margin, respectively. A U–Pb single zircon age of 761 ± 33 Ma for volcanoclastic rocks of the Ganghe unit demonstrates a Neoproterozoic deposition age, concordant with inferred rifting at that time. Eclogite facies parageneses in the gneisses and both cover units, along with P–T data demonstrate regional UHPM in the Dabie Shan.

Notes: The Xugou garnet peridotite body of the southern Sulu ultrahigh-pressure (UHP) terrane is enclosed in felsic gneiss, bounded by faults, and consists of harzburgite and lenses of garnet clinopyroxenite and eclogite. The peridotite is composed of variable amounts of olivine (Fo91), enstatite (En92−93), garnet (Alm20−23Prp53−58Knr6−9Grs12−18), diopside and rare chromite. The ultramafic protolith has a depleted residual mantle composition, indicated by a high-Mg number, very low CaO, Al2O3 and total REE contents compared to primary mantle and other Sulu peridotites. Most garnet (Prp44−58) clinopyroxenites are foliated. Except for rare kyanite-bearing eclogitic bands, most eclogites contain a simple assemblage of garnet (Alm29−34Prp32−50Grs15−39) + omphacite (Jd24−36) + minor rutile. Clinopyroxenite and eclogite exhibit LREE-depleted and LREE-enriched patterns, respectively, but both have flat HREE patterns. Normalized La, Sm and Yb contents indicate that both eclogite and garnet clinopyroxenite formed by high-pressure crystal accumulation (+ variable trapped melt) from melts resulting from two-stage partial melting of a mantle source.Recrystallized textures and P–T estimates of 780–870 °C, 5–7 GPa and a metamorphic age of 231 ± 11 Ma indicate that both mafic and ultramafic protoliths experienced Triassic UHP metamorphism in the P–T forbidden zone with an extremely low thermal gradient (〈 5 °C km−1), and multistage retrograde recrystallization during exhumation. Develop of prehnite veins in clinopyroxenite, eclogite, felsic blocks and country rock gneiss, and replacements of eclogitic minerals by prehnite, albite, white mica, and K-feldspar indicate low-temperature metasomatism.

Notes: This paper provides further evidence for the ongoing discussion as to whether the Dabie UHPM belt formed in Triassic or Palaeozoic time, and whether the Sulu UHPM belt formed in Triassic or Neoproterozoic time. Combined use of laser Raman spectrometer (LR), cathodoluminescence imaging (CL), and ion probe U–Pb in-situ dating (SHRIMP) provided accurate ages of UHPM from rocks collected from Weihai, NE Sulu UHPM belt. LR was used to identify coesite and other UHP minerals as inclusions in zircon separates from an amphibolized peridotite and an eclogite. CL was used to examine the zoning structure of these zircon, and SHRIMP dating was performed on specific spots on zircon to obtain ages of different geological events. An age of 221 ± 12 Ma was obtained for coesite-bearing zircon from the amphibolized peridotite; an age of 228 ± 29 Ma for eclogite was obtained from the lower intercept of a concordia plot. These ages are interpreted as the time of UHPM in the Weihai region. Ultramafic rocks to the east of Weihai yield a magmatic age at 581 ± 44 Ma. The zircon in the ultramafic rocks possibly also records a thermal event at c. 400 Ma, but no independent geological evidence for this event has been found. The eclogite protolith formed in the Middle Proterozoic (1821 ± 19 Ma), which is similar to the age of country rock gneisses of 1847–1744 Ma. The new geochronological data confirm that UHPM occurred in the Triassic in the Sulu area when subduction took the ultramafic body and the eclogite protolith, together with the adjacent supracrustal rocks, to mantle depths.

Notes: Oxygen isotopic compositions of silicates in eclogites and whiteschists from the Kokchetav massif were analyzed by whole-grain CO2-laser fluorination methods. Systematic analyses yield extremely low δ18O for eclogites, as low as −3.9‰ for garnet; these values are comparable with those reported for the Dabie-Sulu UHP eclogites. Oxygen isotopic compositions are heterogeneous in samples of eclogite, even on an outcrop scale. Schists have rather uniform oxygen isotope values compared to eclogites, and low δ18O is not observed. Isotope thermometry indicates that both eclogites and schists achieved high-temperature isotopic equilibration at 500–800 °C. This implies that retrograde metamorphic recrystallization barely modified the peak-metamorphic oxygen isotopic signatures. A possible geological environment to account for the low-δ18O basaltic protolith is a continental rift, most likely subjected to the conditions of a cold climate. After the basalt interacted with low δ18O meteoric water, it was tectonically inserted into the surrounding sedimentary units prior to, or during subduction and UHP metamorphism.

Notes: A combined oxygen-isotope and fluid-inclusion study has been carried out on high- and ultrahigh-pressure metamorphic (HP/UHPM) eclogites and garnet clinopyroxenite from the Dabie-Sulu terranes in eastern China. Coesite-bearing eclogites/garnet clinopyroxenite and quartz eclogites have a wide range in whole-rock δ18OVSMOW, from 0 to 11‰. The high-T oxygen-isotope fractionations preserved between quartz and garnet preclude significant retrograde isotope exchange during exhumation, and the wide range in whole-rock oxygen-isotope composition is thought to be a presubduction signature of the precursors. Aqueous fluids with variable salinities and gas species (N2-, CO2-, or CH4-rich), are trapped as primary inclusions in garnet, omphacite and epidote, and in quartz blebs enclosed within eclogitic minerals. In high-δ18O HP/UHPM rocks from Hujialin and Shima, high-salinity brine and/or N2 inclusions occur in garnet porphyroblasts, which also contain inclusions of coesite, Cl-rich blue amphibole and dolomite. In contrast, in low-δ18O eclogites from Qinglongshan and Huangzhen, the Cl concentrations in amphibole are very low, 〈 0.2 wt.%, and low-salinity aqueous inclusions occur in quartz inclusions in epidote porphyroblasts and in epidote cores. These low-salinity fluid inclusions are believed to be remnants of meteoric water, although the fluid composition was modified during pre- and syn-peak HP/UHPM. Eclogites at Houshuichegou and Hetang contain CH4-rich fluid inclusions, coexisting with high-salinity brine inclusions. Methane was probably formed under the influence of CO2-rich aqueous fluids during serpentinisation of mantle-derived peridotites prior to or during plate subduction. Remnants of premetamorphic low- to high-salinity aqueous fluid with minor N2 and/or other gas species preserved in the Dabie-Sulu HP/UHPM eclogites and garnet clinopyroxenite indicate a great diversity of initial fluid composition in the precursors, implying very limited fluid–rock interaction during syn- and post-peak HP/UHPM.

Notes: Coesite relics were discovered as inclusions in clinopyroxene in eclogite and as inclusions in zircon in felsic and pelitic gneisses from Higher Himalayan Crystalline rocks in the upper Kaghan Valley, north-west Himalaya. The metamorphic peak conditions of the coesite-bearing eclogites are estimated to be 27–32 kbar and 700–770 °C, using garnet–pyroxene–phengite geobarometry and garnet–pyroxene geothermometry, respectively. Cathodoluminescence (CL) and backscattered electron (BSE) imaging distinguished three different domains in zircon: inner detrital core, widely spaced euhedral oscillatory zones, and thin, broadly zoned outermost rims. Each zircon domain contains a characteristic suite of micrometre-sized mineral inclusions which were identified by in situ laser Raman microspectroscopy. Core and mantle domains contain quartz, apatite, plagioclase, muscovite and rutile. In contrast, the rim domains contain coesite and minor muscovite. Quartz inclusions were identified in all coesite-bearing zircon grains, but not coexisting with coesite in the same growth domain (rim domain). 206Pb/238U zircon ages reveal that the quartz-bearing mantle domains and the coesite-bearing rim were formed at c. 50 Ma and 46.2 ± 0.7 Ma, respectively. These facts demonstrate that the continental materials were buried to 100 km within 7–9 Myr after initiation of the India–Asia collision (palaeomagnetic data from the Indian oceanic floor supports an initial India-Asia contact at 55–53 Ma). Combination of the sinking rate of 1.1–1.4 cm year−1 with Indian plate velocity of 4.5 cm year−1 suggests that the Indian continent subducted to about 100 km depth at an average subduction angle of 14–19°.

Notes: The Solund–Hyllestad–Lavik area affords an excellent opportunity to understand the ultrahigh-pressure Scandian orogeny because it contains a near-complete record of ophiolite emplacement, high-pressure metamorphism and large-scale extension. In this area, the Upper Allochthon was intruded by thec. 434 Ma Sogneskollen granodiorite and thrust eastward over the Middle/Lower Allochthon, probably in the Wenlockian. The Middle/Lower Allochthon was subducted to c. 50 km depth and the structurally lower Western Gneiss Complex was subducted to eclogite facies conditions at c. 80 km depth by c. 410–400 Ma. Within 〈 5–10 Myr, all these units were exhumed by the Nordfjord–Sogn detachment zone, producing shear strains 〉 100. Exhumation to upper crustal levels was complete by c. 403 Ma. The Solund fault produced the last few km of tectonic exhumation, bringing the near-ultrahigh-pressure rocks to within c. 3 km vertical distance from the low-grade Solund Conglomerate.

Notes: New petrographic evidence and a review of the latest radiometric age data are taken to indicate that formation of the ultra-high pressure (UHP) eclogites within the Western Gneiss Region of Norway probably occurred within the 400–410 Ma time frame. Thus, this event took place significantly later than the previous, widely accepted age of c. 425 Ma for the timing of the high pressure metamorphism in this part of the Scandinavian Caledonides. Garnet growth under UHP (coesite-stable) conditions is recognised as a discrete, younger event following on from earlier garnet formed under firstly amphibolite facies then quartz-stable, eclogite facies conditions. Currently, the best constrained and most precise age, specifically for UHP mineral growth, is the 402 ± 2 Ma U–Pb age for metamorphic zircon (some of which retain coesite inclusions) from the Hareidland eclogite. Exhumation must have followed shortly thereafter and, based on synoptic pressure–temperature and depth–time curves, must have been very fast. Our data and those of others indicate an initial fast exhumation to about 35 km depth by about 395 Ma at a mean rate of about 10 mm a−1. This rapid exhumation rate may have been driven by the appreciable residual buoyancy of the deeply subducted continental crustal slab due to incomplete eclogitization of the dominant Proterozoic orthogneisses during the short-lived UHP event. Subsequent exhumation to 8–10 km depth by about 375 Ma occurred at a much slower mean rate of about 1.3 mm a−1 with the late-stage extensional collapse of the Caledonian orogen playing an increasingly important role, especially in the final unroofing of the Western Gneiss Region with some remarkably preserved UHP rocks.

Notes: Widespread evidence for ultrahigh-pressure (UHP) metamorphism is reported in the Dulan eclogite-bearing terrane, the North Qaidam–Altun HP–UHP belt, northern Tibet. This includes: (1) coesite and associated UHP mineral inclusions in zircon separates from paragneiss and eclogite (identified by laser Raman spectroscopy); (2) inclusions of quartz pseudomorphs after coesite and polycrystalline K-feldspar + quartz in eclogitic garnet and omphacite; and (3) densely oriented SiO2 lamellae in omphacitic clinopyroxene. These lines of evidence demonstrate that the Dulan region is a UHP metamorphic terrane. In the North Dulan Belt (NDB), eclogites are characterized by the peak assemblage Grt + Omp + Rt + Phn + Coe (pseudomorph) and retrograde symplectites of Cpx + Ab and Hbl + Pl. The peak conditions of the NDB eclogites are P = 2.9–3.2 GPa, and T = 631–687 °C; the eclogite shows a near-isothermal decompression P–T path suggesting a fast exhumation. In the South Dulan Belt (SDB), three metamorphic stages are recognized in eclogites: (1) a peak eclogite facies stage with the assemblage Grt + Omp + Ky + Rt + Phn at P = 2.9–3.3 GPa and T = 729–746 °C; (2) a high-pressure granulite facies stage with Grt + Cpx (Jd 〈 30) + Pl (An24–29) + Scp at P = 1.9–2.0 GPa, T = 873–948 °C; and (3) an amphibolite facies stage with the assemblage Hbl + Pl + Ep/Czo at P = 0.7–0.9 GPa and T = 660–695 °C. The clockwise P–T path of the SDB eclogites is different from the near-isothermal decompression P–T path from the NDB eclogites, which suggests that the SDB was exhumed to a stable crustal depth at a slower rate. In essence these two sub-belts formed in different tectonic settings; they both subducted to mantle depths of around 100 km, but were exhumed to the Earth's surface separately along different paths. This UHP terrane plays an important role in understanding continental collision in north-western China.

Notes: Mineral assemblages in Al2O3-rich, SiO2- and K2O-poor metapelitic rocks from the western Odenwald Crystalline Complex (Variscan Mid-German Crystalline Rise, southern Germany) include corundum, spinel, cordierite, sillimanite, garnet and staurolite. Quartz is absent from almost all samples. Therefore, the applicability of conventional geothermobarometry is very limited or even impossible. Detailed petrographic investigation on selected samples permits inference of the sequence of appearance and disappearance of several mineral assemblages. The recognition of such partial re-equilibration stages and their associated mineral assemblages, together with mineral stabilities predicted from KFMASH pseudosections, enables the determination of the pressure-temperature (P–T) trajectories experienced by these rocks during the Variscan metamorphism. The rocks were metamorphosed under low-P/high-T conditions and underwent an anti-clockwise P–T evolution. A pressure increase from about 2 kbar to 4 ± 0.5 kbar was accompanied by heating. Peak metamorphic conditions were reached at pressures of 4 ± 0.5 kbar and temperatures of at least 640 °C, probably even higher. The retrograde evolution is characterised by near-isobaric cooling from ≥ 640 °C to approximately 550 °C. The rocks underwent the anti-clockwise evolution in a subduction-related magmatic arc setting. The close spatial association of the low-P/high-T rocks with recently discovered metabasic eclogites in the eastern part of the Odenwald Crystalline Complex may indicate a fossil paired metamorphic belt in the Central European Variscides.

Notes: The influx of a H2O–CO2-dominated fluid into actinolite-bearing metabasic rocks during greenschist facies metamorphism in the Kalgoorlie area of Western Australia resulted in a zoned alteration halo around inferred fluid conduits that contain gold mineralisation. The alteration halo is divided into two outer zones, the chlorite zone and the carbonate zone, and an inner pyrite zone adjacent to the inferred fluid conduits. Reaction between the fluid and the protolith resulted in the breakdown of actinolite and the development of chlorite, dolomite, calcite and siderite. In addition, rocks in the pyrite zone developed muscovite-bearing assemblages as a consequence of the introduction of potassium by the fluid. Mineral equilibria calculations undertaken using the computer software thermocalc in the model system Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–CO2 show that mineral assemblages in the outer zones of the alteration halo are consistent with equilibrium of the protoliths with a fluid of composition XCO2 = CO2/(CO2 + H2O) = 0.1–0.25 for temperatures of 315–320 °C. The inner zone of the alteration halo reflect equilibrium with a fluid of composition XCO2≈ 0.25. Fluid-rock buffering calculations show that the alteration halo is consistent with interaction with a single fluid composition and that the zoned structure of the halo reflects the volume of this fluid with which the rocks reacted. This fluid is likely to have also been the one responsible for the gold mineralisation at Kalgoorlie.

Notes: Nanometric solid inclusions in diamond incorporated in garnet and zircon from felsic gneiss of the Kokchetav massif, Kazakhstan, have been examined utilizing electron microscopy and focused ion beam techniques. Host garnet and zircon contain numerous pockets of multiple inclusions, which consist of 1–3 diamond crystals intergrown with quartz, phengite, phlogopite, albite, K-feldspar, rutile, apatite, titanite, biotite, chlorite and graphite in various combinations. Recalculation of the average chemical composition of the entrapped fluid represented by multiple inclusion pockets indicates that such fluid contained a low wt% of SiO2, suggesting a relatively low-temperature fluid rather than a melt. Transmission electron microscopy revealed that the diamond contains abundant nanocrystalline inclusions of oxides, rare carbonates and silicates. Within the 15 diamond crystals studied, abundant inclusions were found of SiO2, TiO2, FexOy, Cr2O3, ZrSiO4, and single grains of ThxOy, BaSO4, MgCO3, FeCr2O4 and a stoichiometric Fe-rich pyroxene. The diversity of trace elements within inclusions of essentially the same stoichiometry suggests that the Kokchetav diamond crystallized from a fluid containing variable amounts of Si, Fe, Ti, Cr, Zr, Ba, Mg and Th and other minor components such as K, Na, P, S, Pb, Zn, Nb, Al, Ca, Cl. Most of the components in crystals included in diamond appear to have their origin in the subducted metasediments, but some of them probably originate from the mantle. It is concluded that Kokchetav diamond most likely crystallized from a COH-rich multicomponent supercritical fluid at a relatively low temperature (hence the apparently low content of rock-forming elements), and that the diversity of major and minor components suggests interactions between subducted metasediments and mantle components.

Notes: A high-P granulite facies gneiss complex occurs in north-west Payer Land (74°28′−74°47′N) in the central part of the East Greenland Caledonian (Ordovician–Devonian) orogen. High-P metamorphism of the Payer Land gneiss complex resulted in formation of the assemblages Grt + Cpx + Amp + Qtz + Ru ± Pl in mafic rocks, and Grt + Ol + Cpx + Opx + Spl in rare ultramafic pods. Associated metapelites experienced anatexis in the kyanite stability field. Peak metamorphic assemblages formed around 800–850 °C at pressures of c. 1.4–1.7 GPa, corresponding to crustal depths of c. 50 km. Mafic granulites contain abundant reaction textures, including the replacement of garnet by symplectites of Opx + Spl + Pl, indicating that the high-P event was followed by decompression while the granulites remained at elevated temperatures. Charnockitic gneisses from Payer Land show evidence of late Archean (c. 2.8–2.4 Ga) crustal growth and subsequent Palaeoproterozoic (c. 1.85 Ga) metamorphism. The gneiss complex experienced intense reworking during the Caledonian continental collision. On the basis of Caledonian monazite ages recorded from the high-P anatectic metapelites, the clockwise P–T evolution and formation of the high-P granulite facies assemblages is related to Caledonian crustal thickening, which resulted in formation of eclogites approximately 300 km north of Payer Land. The Payer Land granulites comprise a metamorphic core complex, which is separated from the overlying low-grade supracrustal rocks (the Neoproterozoic Eleonore Bay Supergroup) by a late Caledonian extensional fault zone, the Payer Land Detachment. The steep, nearly isothermal, unloading P–T path recorded by the granulites can be explained by erosional and tectonic unroofing along the Payer Land Detachment.

Notes: High-pressure granulites are characterised by the key associations garnet-clinopyroxene-plagioclase-quartz (in basic rocks) and kyanite-K-feldspar (metapelites and felsic rocks) and are typically orthopyroxene-free in both basic and felsic bulk compositions. In regional metamorphic areas, two essential varieties exist: a high- to ultrahigh-temperature group and a group representing overprinted eclogites. The high- to ultrahigh-temperature type formerly contained high-temperature ternary feldspar (now mesoperthite) coexisting with kyanite, is associated with garnet peridotites, and formed at conditions above 900 °C and 1.5 GPa. Clinopyroxene in subordinate basic rocks is Al-rich and textural evidence points to a high-pressure–high-temperature melting history. The second variety contains symplectite-like or poikilitic clinopyroxene-plagioclase intergrowths indicating former plagioclase-free, i.e. eclogite facies assemblages. This type of rock formed at conditions straddling the high-pressure amphibolite/high-pressure granulite field at around 700–850 °C, 1.0–1.4 GPa. Importantly, in the majority of high-pressure granulites, orthopyroxene is secondary and is a product of reactions at pressures lower than the peak recorded pressure. In contrast to low- and medium-pressure granulites, which form at conditions attainable in the mid to lower levels of normal continental crust, high-pressure granulites (of nonxenolith origin) mostly represent rocks formed as a result of short-lived tectonic events that led to crustal thickening or subduction of the crust into the mantle. Short times at high-temperature conditions are reflected in the preservation of prograde zoning in garnet and pyroxene. High-pressure granulites of both regional types, although rare, are known from both old and young metamorphic terranes (e.g. c. 45 Ma, Namche Barwa, E Himalaya; 400–340 Ma, European Variscides; 1.8 Ga Hengshan, China; 1.9 Ga, Snowbird, Saskatchewan and 2.5 Ga Jianping, China). This spread of ages supports proposals suggesting that thermal and tectonic processes in the lithosphere have not changed significantly since at least the end of the Archean.

Notes: The Mollendo–Camana Block (MCB) is a 50 × 150 km Precambrian inlier of the Andean belt that outcrops along the Pacific coast of southern Peru. It consists of stromatic migmatites of Paleoproterozoic heritage intensely metamorphosed during the Grenville event (c. 1 Ga; U-Pb and U-Th-Pb ages on zircon and monazite). In the migmatites, aluminous mesosomes (FMAS) and quartzofeldspathic leucosomes (KFMASH), contain various amounts of K-feldspar (Kfs), orthopyroxene (XMg Opx = 0.86), plagioclase (Pl), sillimanite (Sil; exceptionally kyanite, Ky) ilmenite (Ilm), magnetite (Mag), quartz (Qtz), and minor amounts of garnet (XMg Grt = 0.60), sapphirine (XMg Spr = 0.87), cordierite (XMg Crd = 0.92) and biotite (XMg Bt = 0.83). The ubiquitous peak mineral assemblage is Opx-Sil-Kfs-Qtz-(± Grt) in most of the MCB, which, together with the high Al content of orthopyroxene (10% Al2O3) and the local coexistence of sapphirine-quartz, attest to regional UHT metamorphism (〉 900 °C) at pressures in excess of 1.0 GPa. Fluid-absent melting of biotite is responsible for the massive production of orthopyroxene that proceeded until exhaustion of biotite (and most of the garnet) in the southern part of the MCB (Mollendo-Cocachacra areas). In this area, a first stage of decompression from 1.1–1.2 to 0.8–0.9 GPa at temperatures in excess of 950 °C, is marked by the breakdown of Sil-Opx to Spr-Opx-Crd assemblages according to several bivariant FMAS reactions. High-T decompression is also shown by Mg-rich garnet being replaced by Crd-Spr- and Crd-Opx-bearing symplectites, and reacting with quartz to produce low-Al-Opx-Sil symplectites in quartz-rich migmatites. Neither osumilite nor spinel-quartz assemblages being formed, isobaric cooling at about 0.9 GPa probably followed the initial decompression and proceeded with massive precipitation of melts towards the (Os) invariant point, as demonstrated by Bt-Qtz-(± pl) symplectites in quartz-rich migmatites (melt + Opx + Sil = Bt + Grt + Kfs + Qtz). Finally, Opx rims around secondary biotite attest to late fluid-absent melting, compatible with a second stage of decompression below 900 °C. The two stages of decompression are interpreted as due to rapid tectonic denudation whereas the regional extent of UHT metamorphism in the area, probably results from large-scale penetration of hot asthenospheric mantle at the base of an over-thickened crust.

Notes: The Arthur River Complex is a suite of gabbroic to dioritic orthogneisses in northern Fiordland, New Zealand. The Arthur River Complex separates rocks of the Median Tectonic Zone, a Mesozoic island arc complex, from Palaeozoic rocks of the palaeo-Pacific Gondwana margin, and is itself intruded by the Western Fiordland Orthogneiss. New SHRIMP U/Pb single zircon data are presented for magmatic, metamorphic and deformation events in the Arthur River Complex and adjacent rocks from northern Fiordland. The Arthur River Complex orthogneisses and dykes are dominated by magmatic zircon dated at 136–129 Ma. A dioritic orthogneiss that occurs along the eastern margin of the Complex is dated at 154.4 ± 3.6 Ma and predates adjacent plutons of the Median Tectonic Zone. Rims on zircon cores from this sample record a thermal event at c. 120 Ma, attributed to the emplacement of the Western Fiordland Orthogneiss. Migmatitic Palaeozoic orthogneiss from the Arthur River Complex (346 ± 6 Ma) is interpreted as deformed wall rock. Very fine rims (5–20 µm) also indicate a metamorphic age of c. 120–110 Ma. A post-tectonic pegmatite (81.8 ± 1.8 Ma) may be related to phases of crustal extension associated with the opening of the Tasman Sea. The Arthur River Complex is interpreted as a batholith, emplaced at mid-crustal levels and then buried to deep crustal levels due to convergence of the Median Tectonic Zone arc and the continental margin.

Notes: Petrological data provide a good record of the thermal structure of deeply eroded orogens, and, in principle, might be used to relate the metamorphic structure of an orogen to its deformational history. In this paper, we present two-dimensional thermal modelling of various subduction models taking into account varying wedge geometry as well as variation of density and topography with metamorphic reactions.The models clearly show that rock type accreted in the wedge has important effects on the thermal regime of orogenic wedges. The thermal regime is dominated by radiogenic heat production. Material having high radioactive heat production, like the granodioritic upper crust, produces high temperature metamorphism (amphibolitic conditions). Material with low radioactive heat production results in low temperature metamorphism of greenschist or blueschist types depending on the thickness of the wedge.Application of this model to seemingly unrelated areas of the Central Alps (Lepontine Dome, Grisons) and Eastern Alps (Tauern Window) explains the coexistence and succession of distinct Barrovian and blueschist facies metamorphic conditions as the result of a single, continuous tectonic process in which the main difference is the composition of the incoming material in the orogenic wedge. Accretion of the European upper continental crust in the Lepontine and Tauern Domes produces Barrovian type metamorphism while accretion of oceanic sediments results in blueschist facies metamorphism in the Valaisan domain.

Notes: Abstract Logging, fire suppression, and urbanization have all contributed to the serious decline and fragmentation of Pinus palustris (longleaf pine) ecosystems in the southeastern United States. Effective management of the remaining patches of these pyrogenic communities must incorporate periodic low-intensity fires, even where they are located on private lands in populated urban and suburban areas. To explore the effects of fire and its potential use for restoration and management of small fragments surrounded by suburban development, we conducted growing season prescribed fires in remnant longleaf pine sandhill patches in the suburbs of Gainesville, Florida. Density and composition of hardwoods were surveyed pre-burn and 1 and 9 months post-burn. Woody stem density decreased in the burn plots, predominantly in the smaller size classes. Flowering responses of forbs and small shrubs were surveyed six times post-burn for 1 year. Overall, the burns did not yield greater densities of flowering stems, but burn patches had higher species richness and diversity than control patches. In addition, there were consistently greater numbers of “showy flowered” sandhill species in flower in burn patches relative to controls. The results of this research demonstrate that prescribed fire can be used for restoration and management of small remnants of longleaf pine sandhill in suburban neighborhoods. It is also clear that although a single prescribed burn can be effective, it will take more than one burn to attain desired restoration goals in degraded longleaf remnants.