ALBERT

Beschreibung: Potential changes in glacier area, mass balance and runoff in the Yarkant River Basin (YRB) and Beida River Basin (BRB) are projected for the period from 2011 to 2050 employing the modified monthly degree-day model forced by climate change projection. Future monthly air temperature and precipitation were derived from the simple average of 17, 16 and 17 GCM projections following the A1B, A2 and B1 scenarios, respectively. These data were downscaled to each station employing the Delta method, which computes differences between current and future GCM simulations and adds these changes to observed time-series. Model parameters calibrated with observations or results published in the literature between 1961 and 2006 were kept unchanged. Annual glacier runoff in YRB is projected to increase until 2050, and the total runoff over glacier area in 1970 is projected to increase by about 13–35% during 2011–2050 relative to the average during 1961–2006. Annual glacier runoff and the total runoff over glacier area in 1970 in BRB is projected to increase initially and then to reach a tipping point during 2011–2030. There are prominent increases in summer, but only small increase in May and October of glacier runoff in YRB, and significantly increases during late spring and early summer and significant decreases in July and late summer of glacier runoff in BRB. This study highlights the great differences among basins in their response to future climate warming. The specific runoff from areas exposed after glacier retreat relative to 1970 is projected to general increasing, which must be considered when evaluating the potential change of glacier runoff. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: The ~3240 Ma Panorama volcanic-hosted massive sulfide (VHMS) district is unusual for its high degree of exposure and low degree of postdepositional modification. In addition to typical seafloor VHMS deposits, this district contains greisen- and vein-hosted Mo-Cu-Zn-Sn mineral occurrences that are contemporaneous with VHMS orebodies and are hosted by the Strelley granite complex, which also drove VHMS circulation. Hence the Panorama district is a natural laboratory to investigate the role of magmatic-hydrothermal fluids in VHMS hydrothermal systems. Regional and proximal high-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by chlorite-quartz ± albite assemblages, with lesser low-temperature sericite-quartz ± K-feldspar assemblages. These assemblages are typical of VHMS hydrothermal systems. In contrast, the alteration assemblages associated with granite-hosted greisens and veins include quartz-topaz-muscovite-fluorite and quartz-muscovite (sericite)-chlorite-ankerite. These vein systems generally do not extend into the overlying volcanic pile. Fluid inclusion and stable isotope studies suggest that the greisens were produced by high-temperature (~590°C), high-salinity (38–56 wt % NaCl equiv) fluids with high densities (〉1.3 g/cm 3 ) and high 18 O (9.3 ± 0.6 ). These fluids are compatible with the measured characteristics of magmatic fluids evolved from the Strelley granite complex. In contrast, fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90°–270°C), lower salinity (5.0–11.2 wt % NaCl equiv), with lower densities (0.88–1.01 g/cm 3 ) and lower 18 O (–0.8 ± 2.6 ). These fluids are compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the granite complex near the contact with the volcanic pile, were intermediate in temperature and isotopic composition between the greisen and volcanic pile fluids (T = 240°–315°C; 18 O = 4.3 ± 1.5 ) and are interpreted to indicate mixing between the two end-member fluids. Evidence of mixing between evolved seawater and magmatic-hydrothermal fluid within the granite complex, together with the lack of evidence for a magmatic component in fluids from the volcanic pile, suggest partitioning of magmatic-hydrothermal from evolved seawater hydrothermal systems in the Panorama VHMS system. This separation is interpreted to result from either the swamping of a relatively small magmatic-hydro-thermal system by evolved seawater or density contrasts precluding movement of magmatic-hydrothermal fluids into the volcanic pile. Variability in the salinity of fluids in the volcanic pile, combined with evidence for mixing of low- and high-salinity fluids in the massive sulfide lens, is interpreted to indicate that phase separation occurred within the Panorama hydrothermal system. Although we consider this phase separation to have most likely occurred at depth within the system, as has been documented in modern VHMS systems, the data do not allow the location of the inferred phase separation to be determined.

Beschreibung: Author(s): Purnima Singh, A. K. Singh, A. N. Wilson, I. Ragnarsson, H. Hübel, A. Bürger, M. P. Carpenter, S. Chmel, P. Fallon, G. B. Hagemann, B. Herskind, Hoa Ha, R. V. F. Janssens, K. Juhász, A. Kardan, T. L. Khoo, G. Kondev, A. Korichi, T. Lauritsen, B. M. Nyakó, J. Rogers, G. Sletten, J. Timár, and S. Zhu High-spin states in 123 I were populated in the reaction 80 Se( 48 Ca, p 4 n ) 123 I at a beam energy of 207 MeV and γ -ray coincidence events were measured using the Gammasphere spectrometer. Three weakly populated, high-spin rotational bands have been discovered with characteristics similar to those of the l... [Phys. Rev. C 86, 067305] Published Mon Dec 17, 2012

Beschreibung: Author(s): Y. C. Zhang, Q. A. Ijaz, W. C. Ma, G. B. Hagemann, M. P. Carpenter, P. Chowdhury, D. M. Cullen, M. K. Djongolov, D. J. Hartley, R. V. F. Janssens, T. L. Khoo, F. G. Kondev, T. Lauritsen, E. Ngiojoi-Yogo, S. Ødegård, L. L. Riedinger, S. V. Rigby, D. G. Roux, D. T. Scholes, R. B. Yadav, and S. Zhu High-spin properties of the nucleus 171 Hf were studied through the 128 Te( 48 Ca,5 n ) reaction. Previously known bands have been extended to significantly higher spins and four new bands have been extracted from these data. The results are discussed within the framework of the cranked shell model aided ... [Phys. Rev. C 85, 064307] Published Thu Jun 07, 2012

Beschreibung: The banded iron formation (BIF)-hosted iron ore deposits in the lower greenstone succession of the Koolyanobbing greenstone belt, 50 km north of Southern Cross in Western Australia, are a ~200 Mt high-grade Fe (〉58%) pre-mining resource and represents one of the most important iron ore districts in the Yilgarn craton. Four hypogene alteration (ore-forming) stages and one supergene upgrading event took place: (1) During ore stage 1, LREE-depleted, transition metal-enriched, Mg-Fe (±Ca) carbonates replaced quartz in BIFs. The deposit-scale alteration was most likely induced by devolatilization of sea-floor–altered, Ca-Si–depleted mafic rocks in the vicinity of the BIF during early regional (syn-D1), very low to low-grade metamorphism and was most strongly developed on reactivated BIF-basalt contacts. (2) Ore stage 2 involved the formation of patchy magnetite ore by a syn-D2 to -D4 dissolution of early carbonate. Enrichment of Fe2O3total in magnetite iron ore was by a factor of 2 to 2.4, and compatible trace elements in magnetite, such as Ga, V, and Al, were immobile. A subdeposit-scale ferroan talc-footprint proximal to magnetite iron ore in the largest deposit (K deposit) was associated with ore stage 2 and resulted from dissolution of magnesite due to reaction with silica in the BIF under greenschist facies conditions and potentially high fluid/rock ratio. (3) Magnetite growth, during ore stage 3, forming granular magnetite-martite ore is related to a subsequent hydrothermal event, occurring locally throughout the belt, especially in D2b faults. (4) Ore stage 4 was associated with Fe-Ca-P-(L)REE-Y–enriched hydrothermal fluids, possibly from a magmatic source such as the postmetamorphic Lake Seabrook granite that crops out about 10 km west of the Koolyanobbing deposits and at the southern margin of the greenstone belt. These Ca-enriched fluids interacted with distal metamorphosed mafic rock and influenced the BIF-ore system in a small number of deposits. They were channelled through regional D4 faults and caused specularite-dolomite-quartz alteration, resulting in Fe grades of up to 68%. (5) Supergene upgrade (ore stage 5) by (further) gangue leaching in the weathering zone was most effective in carbonate-altered BIFs and magnetite ore. This process, together with supergene martitization and goethite replacement of magnetite, led to the formation of high-grade, locally (at K deposit) high P goethite-martite ore. At Koolyanobbing, the two geochemically distinct stages of Archean carbonate alteration clearly controlled the formation of hypogene magnetite-specularite-martite–rich ore and recent supergene modification, including the further upgrade of Fe ore.

Beschreibung: Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image analysis is a proven method for mapping mineral and geochemical zonation associated with a variety of ore types, including orogenic Au, porphyry Cu-(Mo), porphyry-skarn, Pb-Zn-Au, and Mn systems. Only recently has this technique been applied, in a general sense, to mineral alteration mapping and exploration for Fe ore deposits hosted by banded iron formations (BIFs). For this reason, the Archean Weld Range greenstone belt that hosts the Beebyn and Madoonga Fe ore deposits has been chosen as a case study area to test the effectiveness of ASTER imaging techniques for the identification of Fe orebodies. Banded iron formations in the Weld Range district crop out as a series of parallel, 10- to 500-m-wide, 55 wt % Fe) iron ore deposits host Archean hypogene magnetite and specular hematite orebodies that are locally replaced by more recently formed, supergene goethite-hematite ore within several hundred meters of the present erosion surface. A common feature of all ore types hosted by BIFs is a high Fe content relative to SiO2. Consequently, all types of Fe ore in the Weld Range district are best identified by the ferric iron to silica index and the opaques to silica index, for the reason that these ASTER image products detect surfaces that are rich in (opaque) Fe oxide minerals and have a low silica abundance. Gabbro, dolerite, and basalt country rocks located within 20 m of high-grade Fe ore zones in BIFs are altered to hypogene Fe-rich chlorite and, more rarely, are altered by Fe-rich talc. These hypogene alteration zones are best detected by the ferrous iron content in MgOH minerals and carbonates and the FeOH group abundance products, which identify hypogene Fe chlorite and Fe talc. This study demonstrates that integrated remote spectral sensing techniques (ASTER, airborne hyperspectral, and radiometric) used in conjunction with geophysical surveys (aeromagnetic and gravity) are useful for district-scale exploration for Fe orebodies hosted by BIFs. The spectral sensing techniques are a rapid, cost-effective, and efficient means for generating and ranking exploration targets that are located in areas with restricted physical access.

Beschreibung: Global hydrological modeling is affected by three sources of uncertainty: (i) the choice of the global climate model (GCM) used to provide meteorological forcing data; (ii) the choice of future greenhouse gas concentration scenario; and (iii) the choice of the decade used to derive the bias correction parameters. We present a comparative analysis of these uncertainties and compare them to the inter-annual variability. The analysis focuses on discharge, integrated runoff and total precipitation over ten large catchments, representative of different climatic areas of the globe. Results are similar for all catchments, all hydrological variables and throughout the year with few exceptions. We find that the choice of different decadal periods over which to derive the bias correction parameters is a source of comparatively minor uncertainty, while other sources play larger and similarly significant roles. This is true for both the means and the extremes of the studied hydrological variables.

Beschreibung: Author(s): A. Borgschulte, R. Gremaud, A. Züttel, P. Martelli, A. Remhof, A. J. Ramirez-Cuesta, K. Refson, E. G. Bardaji, W. Lohstroh, M. Fichtner, H. Hagemann, and M. Ernst The high energy of hydrogen vibrations in solids is the origin of their strong impact on thermodynamic properties. The peculiar structure of complex hydrides amplifies this impact. We shed light on the vibrational properties of three allotropes of Ca(BH_{4} )_{2} using density-functional theory calc... [Phys. Rev. B 83, 024102] Published Tue Jan 25, 2011

Beschreibung: Author(s): A. Al-Khatib, G. B. Hagemann, G. Sletten, A. K. Singh, H. Amro, G. Benzoni, A. Bracco, P. Bringel, F. Camera, M. P. Carpenter, P. Chowdhury, R. M. Clark, C. Engelhardt, P. Fallon, B. Herskind, H. Hübel, R. V. F. Janssens, T. L. Khoo, T. Lauritsen, A. Neußer-Neffgen, and C. Rønn Hansen Levels excited up to 39.8 MeV and 119/2 units of angular momentum have been populated in ^{125} Xe by the ^{82} Se( ^{48} Ca,5n) ^{125} Xe reaction. High-fold γ-ray coincidence events were measured using the Gammasphere Ge detector array. Nine regular rotational bands extending from levels identifi... [Phys. Rev. C 83, 024306] Published Mon Feb 14, 2011

Beschreibung: A plume of ultrafine particles was observed downwind of the Karlsruhe city and industrial area during the COPS/TRACKS Lagrangian airborne experiment in summer 2007. These ultrafine particles were identified as nucleation-generated aerosols from emissions of a coal-fired power plant and an adjacent refinery, the two main emitters of sulphur dioxide in the area. Modelling the production and growth of aerosols with the COSMO-ART model required, in agreement with the known emission sources, a strong elevated source of sulphur dioxide to explain the temporal evolution of the particle plume. The power plant at Karlsruhe Rheinhafen emits from a 233 m high chimney. The ultrafine particles produced from these fossil-fuel-related sources were the dominant fraction of all ultrafine particles in the rural area of the Kraichgau downwind of Karlsruhe, exceeding all other anthropogenic sources and are suspected of being the major contribution to the number of cloud condensation nuclei (CCN) on a regional scale. Compared to previous investigations on the sulphur chemistry in power-plant plumes, emissions from this power plant, which is equipped with modern stack-gas cleaning technology, had a higher yield of nucleation-mode aerosols as CCN precursors per emitted sulphur dioxide mass. Copyright © 2011 Royal Meteorological Society