ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Springer Science + Business Media  (120,015)
  • 1
    Publication Date: 2017-01-07
    Description: This paper investigates hydrothermal fluid circulation in pre- and syn-tectonic sediments associated with detachments faults. The study area, located in the Err Nappe (SE-Switzerland), preserves a portion of the Adriatic distal margin. Two sites were studied in combining fieldwork, petrography, geochemistry and fluid inclusion analysis: the Piz Val Lunga and Fuorcla Cotschna areas. Both preserve relationships between a spectacularly exposed rift-related extensional detachment fault and its footwall and hangingwall that consist of extensional allochthons and syn- to post-tectonic sediments. These areas register a complex fluid flow history characterized by dolomitization, de-dolomitization, calcite cementation, dolomite and quartz veining and diffuse silicification. Meso- and micro-scale observations allow defining two steps in fluid evolution, which are related to Jurassic rift activity. A first carbonate-rich event occurred before the exhumation of the granitic basement, and this was followed by a second event marked by a change in the fluid towards a silica-dominated chemistry. Homogenization temperatures of fluid inclusions (average Th = 120−130 °C), negative δ18O values and a radiogenic 87Sr/86Sr signatures of carbonate minerals support the hypothesis that both the pre-tectonic rocks constituting the allochthons and the syn-tectonic sediments overlying the detachment fault were crossed by a flux of over-pressured hydrothermal fluids originating from seawater that penetrated into the basement through fault and fracture systems. Field relationships show that this fluid circulation started latest in middle Early Jurassic time, when fault activity migrated from the proximal to the future distal margin. We propose that it evolved chemically as a result of the involvement of the granitic basement forming the footwall of the extensional detachment system. Hydrothermal activity continued until the Middle/Late Jurassic, when tectonic activity shifted outwards leading to the exhumation of mantle rocks. This paper provides an original contribution to better understand the complex evolution of hyperextended continental rift domains and to constrain their thermal regimes. ©2017 Swiss Geological Society
    Print ISSN: 1661-8726
    Electronic ISSN: 1661-8734
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2017-01-10
    Description: The structure of Alpine-type orogenic belts is widely assumed to have been strongly influenced by the inherited structure of the rifted continental margins from which they were formed. The challenge lies in deciphering these influences when orogenic contraction is strong. Contractional deformation in the Kamchia basin (SW Black Sea), caught between the Balkan orogenic belt and the stable Moesian block, has been arrested, preserving the early development of an Alpine-type orogen. We use 3D seismic and well-data to examine the tectonic and stratigraphic structure of this basin. Significant deformation has occurred underwater, through inversion tectonics within the basin itself. However, the basin margin structures have not reactivated. This margin is marked by a low-angle unconformity across which sediment was routed from the platform into the fledgling syn-orogenic basins. Such pathways may explain non-orogen-derived sediment within parts of the ancestral Apennine foredeep, for example. The role of platform margins to focus contractional deformation may have been over-emphasised elsewhere in the Alpine system. Further, the more strongly subsided portions of rifted margins may have accommodated significant contractional deformation through reactivation of basin faults. In the western Alps the complexity of structural juxapositions across thrust sheets in the Brianconnais may reflect these early-orogenic deformations rather than be the product of deformation that happened after tectonic burial. These early deformations are likely to be recorded in early syn-tectonic depositional sequences. ©2017 Swiss Geological Society〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s00015-016-0238-z" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1661-8726
    Electronic ISSN: 1661-8734
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2016-02-01
    Description: Lake Geneserath is located on Beaver Island in northern Lake Michigan, USA. It exhibits evidence of recent eutrophication, despite limited anthropogenic activity in the watershed. The primary goal of this study was to determine the time scale of trophic state change in Lake Geneserath and the influence of multiple stressors. Sediment cores from the shallow northern and deep southern basins of Lake Geneserath were collected and sectioned at 0.5-cm intervals over the topmost 10 cm and at 1.0-cm intervals for the remainder of the core. Total phosphorus, percent organic matter, and chlorophyll derivative concentrations were measured in each section, and core chronology was established using 210Pb. Diatom assemblages were quantified from evenly distributed sections in each core. Geochemical variables in the southern basin core indicate historic (AD ~ 1450–1650) and modern (1848-present) periods of eutrophication, coincident with human disturbance and climate warming events. Geochemical variables in the northern basin core confirm accelerating eutrophication after 1950. The fossil diatom assemblages in both basins shifted from species favoring low nutrients to more nutrient-tolerant taxa. A change from periphytic to planktonic diatom species, concurrent with reduced percent organic matter in the northern basin core, indicates rising water level during the second half of the twentieth century. Lake Geneserath was subject to multiple stressors and its trophic status increased with recent residential development and climate warming. ©2015 Springer Science+Business Media Dordrecht
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2016-04-01
    Description: The hydrological position of a lake within the landscape can affect a number of lake chemical, physical, and biological features, as well as how lakes respond to environmental change. We present a paleolimnological test of the model for landscape position and lake response to climate change proposed by Webster et al. ( 2000 ). To investigate how diatom communities have responded to drought relative to landscape position, we examined sedimentary diatom profiles extending through the twentieth century from an upland site (Crystal Lake) and a lowland site (Allequash Lake) in the Northern Highlands region of north-central Wisconsin (USA). To explore changes in diatom communities at each site, we developed a calibration set and transfer functions from 48 lakes in Wisconsin’s Northern Highland Lake District. We further determined planktic:benthic ratios in the two target lakes, developed lake level models, and investigated the sensitivity of planktic:benthic diatom ratios to climatic variability over the past century. In the upland lake, diatom communities responded indirectly to climate via drought-induced changes in lake level, which resulted in shifts in planktic versus benthic habitat availability. This response of diatoms to changes in habitat availability provides an alternative approach for tracking climate change in upland lakes, though careful consideration must be given to the effect of the bathymetry and its relationship to lake level change and habitat zonation at individual sites. In the lowland lake, changes in diatom communities were related to temperature (and possibly lakewater chemistry) and physical changes secondarily. These results are consistent with the model by Webster et al. ( 2000 ), with chemical changes occurring in the lowland system and little chemical response in the upland system. However, the biological changes in sediment records presented here provide additional insight into how lake response to climatic change is shaped by landscape position, contributing to a clearer understanding of potential changes in ecosystem structure and function during drought conditions. ©2016 Springer Science+Business Media Dordrecht
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2016-01-01
    Description: We report on a unique, new dataset: 49 spits that formed in the various phases of Glacial Lake Algonquin in the northern Great Lakes region, between approximately 13,200 and 11,500 years BP. The spits, which are now subaerially exposed well above the level of the current Great Lakes, trail off from former Lake Algonquin islands and headlands. Several exceed 10 km in length. Steep, eroded headlands coupled with their coarse-textured sediments, suggest that spit development was driven by large waves and strong longshore currents. The lake’s islands and exposed headlands are usually strongly eroded on their eastern margins. Additionally, spits within ≈150–200 km of the former ice margin, and especially the very large spits in northern Michigan, trail to the west, particularly the WNW and SW. Some small spits that lie farther south trail to the east, and others, within confined bays, better reflect the localized littoral circulation systems. Together, these features provide on-the-ground evidence for persistent, easterly, summertime winds in the late Pleistocene in the northern Great Lakes region, supporting paleoclimate models that show southeasterly to easterly air flows, originating from a glacial anticyclone above the Laurentide Ice Sheet. Our research suggests that strong, anticyclonically driven, easterly winds were a key part of the regional circulation within ≈150–200 km of the southern ice margin, while acknowledging that winds may have been more dominantly westerly at locations farther south. The latter conclusion reconciles with the record of loess transport and dune formation on westerly winds during this (and earlier) time periods in the south-central Great Lakes region and the Great Plains of North America. ©2015 Springer Science+Business Media Dordrecht
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2016-01-01
    Description: Improved knowledge of deglaciation processes during the termination of the Last Glacial Maximum on the Tibetan Plateau can provide important information for understanding deglaciations in climate-sensitive high-altitude ecosystems. Little, however, is known about this time interval because most lacustrine sediment records from the Tibetan Plateau are younger than 19,000 years. This study focused on a lake sediment record from Nam Co, south-central Tibetan Plateau, covering the interval from ~23.7 to 20.9 cal ka BP. We analysed the distribution and compound-specific hydrogen isotope composition (δD) of sedimentary n -alkanes, as well as the bulk sediment TOC, TN, δ13Corg and δ15N composition, to infer lake system development. Pronounced changes in environmental conditions between ~21.6 and 21.1 cal ka BP, as well as between 23.1 and 22.5 cal ka BP (Greenland Interstadial 2), were inferred from increased aquatic n -alkane amounts and decreased δD n −C23 values within these time intervals, respectively. Freshwater inputs, which most likely resulted from enhanced glacier melting, caused these changes. Our results suggest that mountain glacier retreat on the Tibetan Plateau started earlier than previously assumed. The required energy for thawing was probably provided by temperature changes caused by reorganization of atmospheric circulation, which has also been recorded in Greenland ice records. ©2015 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10933-015-9863-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2016-01-01
    Description: This study aims at reconstructing the limnological conditions of Lake Narlay, a lake of which a previous study has shown major changes in the trophic reliance on methane of the benthic food web. The evolution of environmental and limnological conditions in and around Lake Narlay is reconstructed using combined analyses of subfossil chironomid remains, sedimentary pigments and organic carbon accumulation rates; whereas potential driving factors are reconstructed by pollen and coprophilous analyses and the use of climate paleo-records. The results suggest a complex combination of climate and anthropogenic pressure to explain the 1200 years of ecological trajectory of Lake Narlay. This ecological trajectory seems to be firstly control by climatic variability, because the colder event of the Little Ice Age induces a significant impact on chironomid assemblage, organic matter influx, and lake productivity. In a more recent time, the anthropogenic control seems to become predominant. The intensification of the agro-pastoral practices in the catchment area of Lake Narlay seems to induce the degradation of the oxygen conditions at the water/sediment interface. In addition, the present study gives also lines of evidence that the human intensification in the watershed of Lake Narlay seems to be the main cause of the major change in the contribution of biogenic methane to the benthic food web. However, the transition stage between the two trophic pathways (from absence to transfer of biogenic methane) involves a progressive change with intermediate limnological conditions, making the assessment of a tipping point in the temporal evolution difficult. Better knowledge of the relationships between the temporal evolution of limnological conditions and the activation of the trophic reliance on methane will require the study of other sites with different conditions. ©2015 Springer Science+Business Media Dordrecht
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2016-03-25
    Description: Recent theoretical models have suggested that bubbles are unlikely to undergo significant migration in a compaction crystal mush by capillary invasion while the system remains partly molten. To test this, experiments of bubble migration during compaction in a crystal-liquid mush were modeled using deformable foam crystals in corn syrup in a volumetric burette, compacted with rods of varying weights. A bubble source was provided by sodium bicarbonate (Alka-Seltzer®). Large bubbles (〉several crystal sizes) are pinched by the compacting matrix and become overpressured and deformed as the bubbles experience a load change from hydrostatic to lithostatic. Once they begin to move, they move much faster than the compaction-driven liquid. Bubbles that are about the same size as the crystals but larger than the narrower pore throats move by deformation or breaking into smaller bubbles as they are forced through pore restrictions. Bubbles that are less than the typical pore diameter generally move with the liquid: The liquid + bubble mixture behaves as a single phase with a lower density than the bubble-free liquid, and as a consequence it rises faster than bubble-free liquid and allows for faster compaction. The overpressure required to force a bubble through the matrix (max grain size = 5 mm) is modest, about 5 %, and it is estimated that for a grain size of 1 mm, the required overpressure would be about 25 %. Using apatite distribution in a Stillwater olivine gabbro as an analog for bubble nucleation and growth, it is suggested that relatively large bubbles initially nucleate and grow in liquid-rich channels that develop late in the compaction history. Overpressure from compaction allows bubbles to rise higher into hotter parts of the crystal pile, where they redissolve and increase the volatile content of the liquid over what it would have without the bubble migration, leading to progressively earlier vapor saturation during crystallization of the interstitial liquid. Bubbles can also move rapidly by ‘surfing’ on porosity waves that can develop in a compacting mush. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2016-03-23
    Description: Between 70 and 175 ka, over 350 km3 of high-silica rhyolite magma erupted both effusively and explosively from within the Yellowstone Caldera. Phenocrysts in all studied lavas and tuffs are remarkably homogenous at the crystal, eruption, and caldera-scale, and yield QUILF temperatures of 750 ± 25 °C. Phase equilibrium experiments replicate the observed phenocryst assemblage at those temperatures and suggest that the magmas were all stored in the upper crust. Quartz-hosted glass inclusions contain 1.0–2.5 % H_2O and 50–600 ppm CO2, but some units are relatively rich in CO2 (300–600 ppm) and some are CO2-poor (50–200 ppm). The CO2-rich magmas were stored at 90–150 MPa and contained a fluid that was 60–75 mol% CO2. CO2-poor magmas were stored at 50–70 MPa, with a more H_2O-rich fluid ( $$X_{{{ ext{CO}}_{2} }}$$ X CO 2  = 40–60 %). Storage pressures and volatiles do not correlate with eruption age, volume, or style. Trace-element contents in glass inclusions and host matrix glass preserve a systematic evolution produced by crystal fractionation, estimated to range from 36 ± 12 to 52 ± 12 wt%. Because the erupted products contain 〈10 wt% crystals, crystal-poor melts likely separated from evolving crystal-rich mushes prior to eruption. In the Tuffs of Bluff Point and Cold Mountain Creek, matrix glass is less evolved than most inclusions, which may indicate that more primitive rhyolite was injected into the reservoir just before those eruptions. The presence and dissolution of granophyre in one flow may record evidence for heating prior to eruption and also demonstrate that the Yellowstone magmatic system may undergo rapid changes. The variations in depth suggest the magmas were sourced from multiple chambers that follow similar evolutionary paths in the upper crust. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
  • 11
    Publication Date: 2016-02-27
    Description: A wide variety of minerals occur as inclusions in igneous zircon and can provide valuable evidence of source magma composition from originally magmatic zircons in metamorphic and clastic sedimentary rocks. However, it is not clear the extent to which zircons preserve the primary composition of their inclusions through a variety of geologic processes. This paper documents a case study of inclusion-rich, originally igneous zircon from an orthogneiss in the Blue Ridge of southwest Virginia. Zircon inclusions isolated from cracks contain 4 % clearly metamorphic phases (mainly in hosts with disturbed U–Pb systems) and otherwise retain distinct plagioclase chemistry, K-feldspar/plagioclase pairs, and biotite with much wider-ranging Mg/(Mg + Fe) than biotite in the rock matrix. A clearly secondary mineralization suite filling cracks in the zircons consists of quartz, biotite, albite, and epidote. Overall, these zircons preserve mineral inclusions distinct from their current host rock (except when exposed to external environments via cracks), demonstrating that non-metamict zircons may preserve their primary inclusion assemblages through later amphibolite to lower granulite facies metamorphism. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Publication Date: 2016-02-25
    Description: An unusual occurrence of Pt-enriched pyroxenites in the Monts de Cristal igneous complex is characterized by unusually high ratios of Pt to other platinum-group elements (PGEs) and very low Cu and sulfide contents. Synchrotron X-ray fluorescence microscopy was used to identify over a hundred discrete grains of platinum minerals and relate their occurrence to textural associations in the host heteradcumulate orthopyroxenites. Element associations, backed up by FIB-SEM and PIXE probe observations, indicate that most of the Pt is associated with either As- or trace Cu–Ni-rich sulfides, or both. Some of the Pt–As grains can be identified as sperrylite, and most are likely to be Pt–Fe alloy. The relative abundances and volumes of Pt minerals to sulfide minerals are very large compared with typical magmatic sulfides. Almost all of the grains observed lie at or within a few tens of μm of cumulus orthopyroxene grain boundaries, and there is no significant difference between the populations of grains located inside or outside plagioclase oikocrysts. These oikocrysts are inferred to have crystallized either at the cumulus stage or very shortly thereafter, on the basis of their relationship to Ti enrichment in the margins of pyroxene grains not enclosed in oikocrysts. This relationship precludes a significant role of trapped intercumulus liquid in Pt deposition or mobilization and also allows a confident inference that Pt-rich and Pt–As-enriched phases precipitated directly from the magma at the cumulus stage. These observations lead to the conclusion that fractionation of Pt from other PGEs in this magmatic system is a consequence of a solubility limit for solid Pt metal and/or Pt arsenide. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Publication Date: 2016-02-25
    Description: Zircon Li concentrations and δ7Li values may potentially trace crustal recycling because continental and mantle-derived zircons yield distinct values. The usefulness of these differences may depend upon the retentivity of zircon to Li concentrations and isotopic ratios. Given the relatively high Li diffusivities measured by Cherniak and Watson (Contrib Mineral Petrol 160: 383–390, 2010 ), we sought to discover the scenarios under which Li mobility might be inhibited by charge-compensating cations. Toward this end, we conducted “in” diffusion experiments in which Li depth profiles of synthetic Lu-doped, P-doped, and undoped zircon were determined by nuclear reaction analysis. In separate experiments, Li was ion-implanted at depth within polished natural zircon slabs to form a Gaussian Li concentration profile. Diffusively relaxed concentration profiles were measured after heating the slabs to determine diffusivities. In all experiments, which ranged from 920 to 650 °C, calculated diffusivities are in agreement with a previously established Arrhenius relationship calibrated on trace-element-poor Mud Tank zircon. Our revised Arrhenius relationship that includes both datasets is: $$D_{ ext{Li}} = 9.60 imes 10{ - 7} exp left[ {frac{{ - 278 pm 8;{ ext{kJ}};{ ext{mol}}{ - 1} }}{ ext{RT}}} ight]{ ext{m}}{ 2} ;{ ext{s}}{ - 1}$$ D Li = 9.60 × 10 - 7 exp - 278 ± 8 kJ mol - 1 RT m 2 s - 1 We also observed that synthetic sector-zoned zircon exhibits near-step-function Li concentration profiles across sectors that correlate with changes in the rare earth element (REE) and P concentrations. This allowed us to examine how Li diffusion might couple with REE diffusion in a manner different than that described above. In particular, re-heating these grains revealed significant Li migration, but no detectable migration of the rare earth elements. Thus, unlike most elements in zircon which are not mobile at the micrometer scale under most time–temperature paths in the crust, Li zoning, relaxation of zoning, or lack of zoning altogether could be used to reveal time–temperature information. Discrete ~10 μm concentration zones of Li within zircon may be partially preserved at 700 °C for tens to hundreds of years, and at 450 °C for millions of years. In this regard, Li zoning in zircon holds significant potential as a geospeedometer, and in some instances as a qualitative indicator of the maximum temperature experienced by the zircon. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Publication Date: 2016-01-23
    Description: Xenoliths of mantle peridotite have been sampled from four kimberlite intrusions, Melton Wold, Hebron, Uintjiesberg and Markt, emplaced through the Mesoproterozoic Namaqua-Natal Belt, along the southern border of the Kaapvaal Craton. Although many of the xenoliths are heavily altered, constituent clinopyroxene, garnet and phlogopite are fresh and have been analysed by electron microprobe for major elements and by laser ablation ICP-MS for trace elements. Primitive mantle-normalised REE abundances in clinopyroxene are all strongly LREE enriched and show a range of patterns including uniformly MREE–HREE sloped (referred to here as ‘normal’), sinusoidal and humped sinusoidal patterns. HREE abundances are extremely low (Yb = 0.3–0.06 × PM). REE_N patterns in coexisting garnets show a similar range of patterns. When normalised to primitive mantle values, trace element patterns in some clinopyroxenes show strong relative depletion in Rb–Ba, Ta–Nb and Ti, with some samples also being relatively depleted in Zr–Hf. These trace element characteristics are indistinguishable from those found in clinopyroxene and garnet from peridotites from the adjacent cratonic mantle. Numerical modelling of reactive porous flow of an enriched metasomatic melt through a geochemically depleted peridotite matrix can account for the full range in observed REE_N patterns. The relative depletion in Rb–Ba, Ta–Nb and Ti can be accounted for by an early crystallisation of phlogopite from the percolating melt. The relative depletion in Zr–Hf in some clinopyroxenes requires either zircon to crystallise in the proximal metasomatic assemblage, or metasomatism by a carbonatitic melt. Modelling results, together with the absence of clinopyroxene with depleted or even partially enriched REE_N patterns, suggest that all clinopyroxene has been modally introduced through metasomatism into an initially highly depleted harzburgitic protolith. The range in Sr and Pb isotopic composition of the clinopyroxenes indicates regional metasomatism by melts of various compositions. The strong HREE_N depletion is interpreted to reflect the effect of initial melt depletion in the early Proterozoic, with melting extending into the spinel stability field requiring an oceanic realm, and again later in the Mesoproterozoic (Namaqua Orogeny). The superimposed incompatible element enrichment indicates subsequent multiple enrichment events by rising alkaline melts similar in composition to kimberlite or ultramafic alkaline lamprophyre, possibly related to Mesozoic plume upwelling beneath the region, that reintroduced clinopyroxene into the depleted Proterozoic harzburgite protolith. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Publication Date: 2016-01-21
    Description: An oceanic crustal origin is the commonly accepted paradigm for mantle-derived eclogites. However, the significance of the aluminous members of the eclogite suite, containing kyanite and corundum, has long been underrated and their role neglected in genetic models of cratonic evolution. Here, we present a geochemical and petrological study of a suite of kyanite- and corundum-bearing eclogites from the Bellsbank kimberlite, S. Africa, which originate from depths between 150 and 200 km. Although clearly of high-pressure provenance, these rocks had a low-pressure cumulative origin with plagioclase and olivine as major cumulate phases. This is shown by the very pronounced positive Eu anomalies, low REE abundances, and δ 18O values lower than the Earth’s mantle. Many chemical features are identical to modern-day troctolitic cumulates including a light REE depletion akin to MORB, but there are also distinguishing features in that the eclogites are richer in Na, Fe, and Ni. Two of the eclogites have a minimum age of ~3.2 Ga, defined by the extremely unradiogenic 87Sr/86Sr (0.7007) in clinopyroxene. Phase equilibria indicate that the parent melts were formed by partial melting below an Archean volcanic center that generated (alkali-)picritic to high-alumina tholeiitic melts from a mantle whose oxygen fugacity was lower than today. Fractional crystallization produced troctolites with immiscible sulfide melt droplets within the mafic crust. Instability of the mafic crust led to deep subduction and re-equilibration at 4–6 GPa. Phase relationships plus the presence of a sample with appreciable modal corundum but no Eu anomaly suggest that kyanite- and corundum-bearing eclogites may also originate as plagioclase-free, higher pressure cumulates of highly aluminous clinopyroxene, spinel, and olivine. This is consistent with the crystallizing phase assemblage from an olivine tholeiitic to picritic magma deeper in the Archean oceanic crust or uppermost mantle. We postulate that the magmatic and subduction processes driving modern plate tectonics already existed in the Meso- to Early Archean. ©2015 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Publication Date: 2016-01-07
    Description: During the onset of caldera cluster volcanism at a new location in the Snake River Plain (SRP), there is an increase in basalt fluxing into the crust and diverse silicic volcanic products are generated. The SRP contains abundant and compositionally diverse hot, dry, and often low-δ18O silicic volcanic rocks produced through time during the formation of individual caldera clusters, but more H_2O-rich eruptive products are rare. We report analyses of quartz-hosted melt inclusions from pumice clasts from the upper and lower Arbon Valley Tuff (AVT) to gain insight into the initiation of caldera cluster volcanism. The AVT, a voluminous, caldera-forming rhyolite, represents the commencement of volcanism (10.44 Ma) at the Picabo volcanic field of the Yellowstone hotspot track. This is a normal δ18O rhyolite consisting of early and late erupted members (lower and upper AVT, respectively) with extremely radiogenic Sr isotopes and unradiogenic Nd isotopes, requiring that ~50 % of the mass of these elements is derived from melts of Archean upper crust. Our data reveal distinctive features of the early erupted lower AVT melt including: variable F concentrations up to 1.4 wt%, homogenous and low Cl concentrations (~0.08 wt%), H_2O contents ranging from 2.3 to 6.4 wt%, CO2 contents ranging from 79 to 410 ppm, and enrichment of incompatible elements compared to the late erupted AVT, subsequent Picabo rhyolites, SRP rhyolites, and melt inclusions from other metaluminous rhyolites (e.g., Bishop Tuff, Mesa Falls Tuff). We couple melt inclusion data with Ti measurements and cathodoluminescence (CL) imaging of the host quartz phenocrysts to elucidate the petrogenetic evolution of the AVT rhyolitic magma. We observe complex and multistage CL zoning patterns, the most critical being multiple truncations indicative of several dissolution–reprecipitation episodes with bright CL cores (higher Ti) and occasional bright CL rims (higher Ti). We interpret the high H_2O, F, F/Cl, and incompatible trace element concentrations in the context of a model involving melting of Archean crust and mixing of the crustal melt with basaltic differentiates, followed by multiple stages of fractional crystallization, remelting, and melt extraction. This multistage process, which we refer to as distillation, is further supported by the complex CL zoning patterns in quartz. We interpret new Δ18O(Qz-Mt) isotope measurements, demonstrating a 0.4 ‰ or ~180 °C temperature difference, and strong Sr isotopic and chemical differences between the upper and lower AVT to represent two separate eruptions. Similarities between the AVT and the first caldera-forming eruptions of other caldera clusters in the SRP (Yellowstone, Heise and Bruneau Jarbidge) suggest that the more evolved, lower-temperature, more H_2O-rich rhyolites of the SRP are important in the initiation of a caldera cluster during the onset of plume impingement. ©2015 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Publication Date: 2016-02-25
    Description: Mantle peridotites from modern supra-subduction zones (SSZs) are important windows through which we can investigate the geodynamic processes active in the subduction factory, but they are unfortunately rare and hard to access. Most ophiolitic peridotites stem from SSZ settings and are therefore good candidates to explore the water budget and deformation in mantle wedges. We present here an integrated study of the geochemistry, deformation microstructures and water contents of olivine and orthopyroxene from the Dongqiao harzburgites, central Tibet. These peridotites are characterized by an absence of interstitial clinopyroxene, the partial replacement of orthopyroxene by olivine, the highly magnesian olivine and chromium spinel, and remarkable LREE enrichments. These features suggest that the Dongqiao harzburgites are highly depleted and have undergone a high degree (~40 %) of partial melting, followed by infiltration of and interaction with melt while they were part of the mantle wedge. Olivine and orthopyroxene show prominent plastic deformation microstructures and have developed significant crystallographic preferred orientations (CPOs), suggestive of dislocation creep deformation. Fourier transform infrared analyses show that olivine is essentially dry, while orthopyroxene contains an average water content of 70 ± 14 wt ppm. We propose that orthopyroxene largely retains its in - situ water content from the mantle source, while olivine completely loses its water during emplacement. The orthopyroxene water contents fall into the lower end of the range observed in SSZ peridotites. We consider that the high degree of partial melting and the interaction with a water-undersaturated melt contribute to the relatively lower water contents in orthopyroxene from the Dongqiao harzburgites. Based on experimentally determined hydrogen partition coefficients between olivine and orthopyroxene, the water contents of olivine in the mantle source are calculated to be 7–9 wt ppm (or 114–147 ppm H/Si), which is consistent with the observed A-type CPOs in olivine. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Publication Date: 2016-02-20
    Description: The halogen-bearing minerals tourmaline, amphibole, and biotite formed during magmatic–hydrothermal processes associated with the late-stage cooling of the Spirit Lake granitoid pluton (Mt. St. Helens, WA) and with the younger sulphide-mineralised rocks of the Margaret Cu–Mo porphyry deposit located entirely within the pluton. Major- and trace-element discrimination suggests that one tourmaline population crystallised from fractionated late-stage melt pockets in granodiorite–monzogranitic dykes of the pluton. These coarse, euhedral, oscillatory, and complexly sector-zoned uvite tourmalines span a limited range in Mg/(Mg + Fe) [Mg#] space (0.4–0.7 apfu) and show the highest Ti, Ca, F, Nb, and Ta contents, and low X-site vacancies (〈0.1 apfu), suggesting slow, ordered crystallisation. Conversely, smaller, microcrystalline, pluton-related vein tourmalines show higher X-site vacancies (〉0.6 apfu), lower Ca and F contents, and the highest Li, As, and HREE contents (〉80 ppm Li, 〉1200 ppm As). This population appears to record direct, rapid crystallisation from magmatic ± meteoric fluid(s) bearing the signature of the breakdown of primary feldspars and pyroxenes, with fluid exsolution from fractionated melt patches likely triggered by the formation of the previous generation of tourmaline. Mineralised porphyry deposit tourmaline compositions from the stockwork span a much larger range in Mg# space (0.05–0.9 apfu) and are almost entirely Ca-free. X-sites of these schorl tourmalines are dominated by Na or vacancies, and the Y-sites are strongly Fe enriched. The highest Mn and Zn concentrations (〉4000 and 〉1000 ppm, respectively) potentially reflect the composition of mineralising fluids during ore deposition. A number of boron isotopic analyses yield predominantly heavy boron, but δ11B values range from −5.2 to 6.2 ‰ and average 1.4 ‰. Whilst most plutonic tourmalines conform to reported a - and c -sector element partitioning models, those from the mineralised porphyry show large and variable sector fractionation differences, suggesting that external controls may also be important. Wider evidence for late-stage pervasive metasomatism by halogen-bearing exsolved fluid(s) is provided by the high Mg# (〉70) secondary amphiboles and biotites from within the Spirit Lake pluton, where the amphiboles are clear replacement products of primary pyroxenes. Fluid halogen fugacity ratios calculated from the biotite compositions overlap with other global mineralised porphyry systems, despite not being immediately associated with sulphide ores. The evidence suggests complex fluid processes and the coincidental development of the mineralised porphyry system within the pluton. Heat, fluids, and metals were therefore likely supplied by a later phase of magmatism, unrelated to the consolidation of the main Spirit Lake granitoid. These new constraints on magmatic–hydrothermal fluid signatures have wider applicability to potentially tracing proximal barren and mineralised processes, and for distinguishing between formation mechanisms for primary and secondary halogen-bearing minerals. ©2016 Springer-Verlag Berlin Heidelberg
    Print ISSN: 0010-7999
    Electronic ISSN: 1432-0967
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
  • 20
    Publication Date: 2016-04-02
    Description: The M7.8 April 25, 2015, Gorkha earthquake in Nepal was produced by a slip on the low-angle Main Himalayan Thrust, a décollement below the Himalaya that emerges at the surface in the south as the Himalayan Frontal Thrust (HFT). The analysis of the SAR interferograms led to the interpretations that the event was a blind thrust and did not produce surface ruptures associated with the seismogenic fault. We conducted a quick field survey along four active faults near the epicentral area around the Kathmandu Valley (the Jhiku Khola fault, Chitlang fault, Kulekhani fault, Malagiri fault and Kolphu Khola fault) from July 18–22, 2015. Those faults are located in the Lesser Himalaya on the hanging side of the HFT. Based on our field survey carried out in the area where most typical tectonic landforms are developed, we confirmed with local inhabitants the lack of any new surface ruptures along these faults. Our observations along the Jhiku Khola fault showed that the fault had some definite activities during the Holocene times. Though in the past it was recognized as a low-activity thrust fault, our present survey has revealed that it has been active with a predominantly right-lateral strike-slip with thrust component. A stream dissecting a talus surface shows approximately 7-m right-lateral offset, and a charcoal sample collected from the upper part of the talus deposit yielded an age of 870 ± 30 y.B.P, implying that the talus surface formed close to 870 y.B.P. Accordingly, a single or multiple events of the fault must have occurred during the last 900 years, and the slip rate we estimate roughly is around 8 mm/year. The fault may play a role to recent right-lateral strike-slip tectonic zone across the Himalayan range. Since none of the above faults showed any relationship corresponding to the April 25 Gorkha earthquake, it is possibility that a potential risk of occurrence of large earthquakes does exist close to the Kathmandu Valley due to movements of these active faults, and more future work such as paleoseismological survey is needed to assess the risk. ©2016 Kumahara et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0429-x" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Publication Date: 2016-04-02
    Description: The Tokai region of Japan is known to be a seismic gap area and is expected to be the source region of the anticipated Tokai earthquake with a moment magnitude of over 8. Interplate slow slip occurred from approximately 2001 and subsided in 2005 in the area adjacent to the source region of the expected Tokai earthquake. Eight years later, the Tokai region again revealed signs of a slow slip from early 2013. This is the first evidence based on a dense Global Positioning System network that Tokai long-term slow slips repeatedly occur. Two datasets with different detrending produce similar transient crustal deformation and aseismic slip models, supporting the occurrence of the Tokai slow slip. The center of the current Tokai slow slip is near Lake Hamana, south of the center of the previous Tokai slow slip. The estimated moments, which increase at a roughly constant rate, amount to that of an earthquake with a moment magnitude of 6.6. If the ongoing Tokai slow slip subsides soon, it will suggest that there are at least two different types of slow slip events in the Tokai long-term slow slip area: that is, a large slow slip with a moment magnitude of over 7 with undulating time evolution and a small one with a moment magnitude of around 6.6 with a roughly linear time evolution. Because the Tokai slow slip changes the stress state to one more favorable for the expected Tokai earthquake, intense monitoring is going on. ©2016 Ozawa et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0430-4" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Publication Date: 2016-03-22
    Description: A phreatic eruption of Mt. Ontake, Japan, started abruptly on September 27, 2014, and caused the worst volcanic calamity in recent 70 years in Japan. We conducted volcanic plume surveys using an electric multirotor unmanned aerial vehicle to elucidate the conditions of Mt. Ontake’s plume, which is flowing over 3000 m altitude. A plume gas composition, sulfur dioxide flux and thermal image measurements and a particle sampling were carried out using the unmanned aerial vehicle for three field campaigns on November 20 and 21, 2014, and June 2, 2015. Together with the results of manned helicopter and aircraft observations, we revealed that the plume of Mt. Ontake was not directly emitted from the magma but was influenced by hydrothermal system, and observed SO2/H2S molar ratios were decreasing after the eruption. High SO2 flux of 〉2000 t/d observed at least until 20 h after the onset of the eruption implies significant input of magmatic gas and the flux quickly decreased to about 130 t/d in 2 months. In contrast, H2S fluxes retrieved using SO2/H2S ratio and SO2 flux showed significantly high level of 700–800 t/d, which continued at least between 2 weeks and 2 months after the eruption. This is a peculiar feature of the 2014 Mt. Ontake eruption. Considering the trends of the flux changes of SO2 and H2S, we presume that majority of SO2 and H2S are supplied, respectively, from high-temperature magmatic fluid of a deep origin and from hydrothermal system. From the point of view of SO2/H2S ratios and fumarolic temperatures, the plume degassing trend after the 2014 eruption is following the similar course as that after the 1979 eruptions, and we speculate the 2014 eruptive activity will cease slowly similar to the 1979 eruption. ©2016 Mori et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0418-0" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Publication Date: 2016-03-17
    Description: Volcanic activity generally causes crustal deformation, which sometimes induces groundwater changes, and both of these phenomena are sometimes detected before volcanic eruptions. Therefore, investigations of crustal deformation and groundwater changes can be useful for predicting volcanic eruptions. The Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, has been observing groundwater pressure at Ohtaki observatory (GOT) since 1998. GOT is about 10 km southeast of the summit of Mt. Ontake. During this observation period, Mt. Ontake has erupted twice, in 2007 and in 2014. Before the 2007 eruption, the groundwater pressure at GOT clearly dropped, but it did not change before or after the 2014 eruption. These observations are consistent with the crustal deformation observed by Global Navigation Satellite System stations of the Geospatial Information Authority of Japan. The difference between the 2007 and 2014 eruptions can be explained if a relatively large magma intrusion occurred before the 2007 eruption but no or a small magma intrusion before the 2014 eruption. ©2016 Koizumi et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0420-6" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Publication Date: 2016-03-17
    Description: The Gorkha earthquake (Nepal, 2015, M w 7.9) triggered many landslides. The most catastrophic mass movement was a debris avalanche that buried several villages in the Langtang valley. In this study, questions are raised about its volume and initiation. I investigate the possibility of high-resolution digital surface models computed from tri-stereo SPOT6/7 images to resolve this issue. This high-resolution dataset enables me to derive an inventory of 160 landslides triggered by this earthquake. I analyze the source of errors and estimate the uncertainties in the landslide volumes. The vegetation prevents to correctly estimate the volumes of landslides that occured in vegetated areas. However, I evaluate the volume and thickness of 73 landslides developing in vegetated-free areas, showing a power law between their surface areas and volumes with exponent of 1.20. Accumulations and depletion volumes are also well constrained for larger landslides, and I find that the main debris avalanches accumulated 6.95 × 106 m3 of deposits in the valley with thicknesses reaching 60 m, and 9.66 × 106 m3 in the glaciated part above 5000 m asl. The large amount of sediments is explained by an initiation of the debris avalanche due to serac falls and snow avalanches from five separate places between 6800 and 7200 m asl over 3 km length. ©2016 Lacroix.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0423-3" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Publication Date: 2016-03-17
    Description: Previous studies reported that the 2015 Gorkha earthquake (Mw 7.8), which occurred in Nepal, triggered landslides in mountainous areas. In Kathmandu, earthquake-induced land subsidence was identified by interpreting local phase changes in interferograms produced from Advanced Land Observing Satellite-2/Phased Array type L-band Synthetic Aperture Radar-2 data. However, the associated ground deformation was not discussed in detail. We studied line-of-sight (LoS) changes from InSAR images in the SE area of Tribhuvan International Airport, Kathmandu. To obtain the change in LoS caused only by local, short-wavelength surface deformation, we subtracted the change in LoS attributed to coseismic deformation from the original change in LoS. The resulting change in LoS showed that the river terrace was driven to the bottom of the river valley. We also studied the changes in LoS in both ascending and descending InSAR images of the area along the Bishnumati River and performed 2.5D analysis. Removing the effect of coseismic deformation revealed east–west and up–down components of local surface deformation, indicating that the river terrace deformed eastward and subsided on the western riverbank of the river. On the east riverbank, the river terrace deformed westward and subsided. However, in the southern part of the river basin, the river terrace deformed westward and was uplifted. The deformation data and field survey results indicate that local surface deformation in these two areas was not caused by land subsidence but by a landslide (specifically, lateral spread). ©2016 Sato and Une.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0425-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Publication Date: 2016-03-17
    Description: Early forecasting of aftershocks has become realistic and practical because of real-time detection of hypocenters. This study illustrates a statistical procedure for monitoring aftershock sequences to detect anomalies to increase the probability gain of a significantly large aftershock or even an earthquake larger than the main shock. In particular, a significant lowering (relative quiescence) in aftershock activity below the level predicted by the Omori–Utsu formula or the epidemic-type aftershock sequence model is sometimes followed by a large earthquake in a neighboring region. As an example, we detected significant lowering relative to the modeled rate after approximately 1.7 days after the main shock in the aftershock sequence of the Mw7.8 Gorkha, Nepal, earthquake of April 25, 2015. The relative quiescence lasted until the May 12, 2015, M7.3 Kodari earthquake that occurred at the eastern end of the primary aftershock zone. Space–time plots including the transformed time can indicate the local places where aftershock activity lowers (the seismicity shadow). Thus, the relative quiescence can be hypothesized to be related to stress shadowing caused by probable slow slips. In addition, the aftershock productivity of the M7.3 Kodari earthquake is approximately twice as large as that of the M7.8 main shock. ©2016 Ogata and Tsuruoka.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0410-8" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
  • 28
    Publication Date: 2016-03-16
    Description: The Thellier method is classical but is still regarded as the most reliable method for paleointensity determination. Recently, many types of additional protocols have been advocated to ensure reliability and make laboratory work more laborious and time-consuming. An automated system coupling a magnetometer and an electric furnace is now of prime importance to cope with the increasing demand. Here, we describe a graphics-based program for controlling a fully automatic system combining a spinner magnetometer and a thermal demagnetizer, and for acquiring and processing the magnetization data. A single fluxgate sensor, which can measure the vector magnetization by spinning and translating a standard-sized 1-in. specimen, was calibrated with a rotatable reference specimen that can make the magnetization parallel or perpendicular to the spinning axis. By placing a cooling chamber between the furnace and the sensor for the updated system, the specimen can be heated up more efficiently to ensure an identical thermal history for the double heatings of the Thellier method. The direction of the vector magnetization was precisely obtained as well as the intensity, the results being comparable with those from an ordinary spinner magnetometer. We present an application of the fully automatic system for a Thellier measurement on a recent lava flow, which took about 24 h for approximately ten-step double heatings without manual operation. ©2016 Fukuma and Kono.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0424-2" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Publication Date: 2016-02-29
    Description: We have been measuring brightness temperature spectra of the atmospheric ozone (O3) emission at 110.83 GHz with a millimeter-wave radiometer (MWR) located at Rikubetsu, Japan, since November 1999. Tropospheric opacities, which were also measured with the MWR and were used to take into account attenuation of the O3 signal from the stratosphere and mesosphere, were corrected using the tropospheric opacity calculated from radiosonde data. Temporal variations of the measured spectral intensity of O3, likely due to degradations of the superconductor–insulator–superconductor receiver and of the vessel for cold calibration load, were also corrected using scaling factors derived from ozonesonde data up to an average height of 35 km and Microwave Limb Sounder (MLS) monthly mean climatology above the sonde height. The vertical profiles of the O3 mixing ratio in the altitude range from 24 to 56 km were retrieved from the spectra with the optimal estimation approach. The retrieval errors from uncertainties in the scaling factor, the corrected tropospheric opacity, and atmospheric temperature, as well as those from spectral noise, were evaluated, and we found that the main retrieval errors resulted from uncertainties in the scaling factor and tropospheric opacity. The retrieved O3 profiles were compared with those from the Solar Backscatter Ultraviolet (SBUV/2), the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), and the MLS instruments onboard satellites. The retrieved O3 mixing ratios at individual levels agreed with the MLS version 3.3 or 3.4 data with an average difference better than ±5 % and a standard deviation of 4–9 %. Additionally, the retrieved O3 profiles were in reasonable agreement with the SABER version 2.0 O3 profiles and the SBUV/2 version 8.6 O3 profiles, in line with the validation results of their satellite data in the earlier literature. ©2016 Ohyama et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0406-4" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Publication Date: 2016-02-29
    Description: In this study, we investigate the driving forces of plate motion, especially those of plate spin motion, that are related to the toroidal components of the global plate velocity field. In previous works, numerical simulations of mantle convection have been used to examine the extent to which toroidal velocity components are naturally generated on the surface, by varying key parameters, notably the rheological properties of plates and plate boundaries. Here, we take the reverse approach and perform analyses of observed plate motions, which show an increase in the toroidal/poloidal ratio at high degrees of spherical harmonic expansion, as well as a rapid change in the plate spin rate and the estimated driving stress around a critical plate size of approximately 1000 km. This quantitative relationship constrains the strength at plate boundaries to 3–75 MPa, which is consistent with several seismological observations, including those from the NE Japan arc associated with the 2011 Tohoku earthquake. ©2016 Matsuyama and Iwamori.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0405-5" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Publication Date: 2016-03-09
    Description: Nondestructive magnetic detection of tephra layers in ice cores will be an important method to identify and correlate stratigraphic horizons of ice bearing volcanic ash particles. Volcanic ash particles were extracted from tephra-bearing ice samples collected from Nansen Ice Field south of the Sør Rondane Mountains, Antarctica. Particles are fresh glassy volcanic ash with diameters of ~50 μm, and chemical composition of the matrix glass belongs to a low-K basaltic andesite group, ranging from SiO2 60–62 wt% and K2O 0.40–0.50 wt%. Considering the grain size of ash particles and chemical composition of volcanic glass, the ash in tephra-bearing ice samples might be originated from the South Sandwich Islands located 2800 km northwest of the sampling sites. Correlations on major element concentrations with tephra layers associated with South Sandwich Islands in EPICA-Dome C, Vostok, and Dome Fuji ice cores show high similarity. Rock magnetic experiments show that the magnetic mineral is pseudo-single-domain titanomagnetite with ulvospinel content of 0.2–0.35 mixed with single-domain to superparamagnetic (titano)magnetite. Small blocks of the tephra-bering ice were measured with a SQUID gradiometer at 1-mm intervals with a spatial resolution of ~3 mm. With DC magnetic field of 25 mT, magnetic signal could be enhanced and detected for all the samples including the one with invisible amount of tephra particles. In order to simulate a thin ash layer in ice core, volcanic ash particles extracted from the tephra-bearing ice were used to fabricate a thin ash layer, which were subsequently magnetized, measured with the gradiometer. The noise level for Z axis gradiometer was about 0.6 pT. Detection limit for a half-cylinder with 29 mm radius and a thickness of 1 mm uniformly magnetized in X axis direction is ~9 × 10−5 A/m, which could be improved down to ~2 × 10−6 A/m by reducing the sensor-to-sample distance to 0.5 mm. ©2016 Oda et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0415-3" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Publication Date: 2016-02-19
    Description: This special issue gathered papers from the International CAWSES-II Symposium (November 18–22, 2013 at Nagoya University, Japan). Climate and Weather of the Sun-Earth System II (CAWSES-II) is an international scientific program sponsored by Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) that continued from 2009 to 2013. The program was established with the aim of significantly enhancing our understanding of the space environment and its impacts on life and society. The International CAWSES-II Symposium was successful with 388 presentations; and from that, 38 papers were published in this special issue. In this preface, we briefly discuss the contents of the special issue as well as the CAWSES-II review papers published in Progress in Earth and Planetary Science (PEPS) in 2014–2015. ©2016 Yamamoto et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0392-6" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Publication Date: 2016-02-27
    Description: In this study, we develop a three-dimensional ionospheric tomography with the ground-based global position system (GPS) total electron content observations. Because of the geometric limitation of GPS observation path, it is difficult to solve the ill-posed inverse problem for the ionospheric electron density. Different from methods given by pervious studies, we consider an algorithm combining the least-square method with a constraint condition, in which the gradient of electron density tends to be smooth in the horizontal direction and steep in the vicinity of the ionospheric F2 peak. This algorithm is designed to be independent of any ionospheric or plasmaspheric electron density models as the initial condition. An observation system simulation experiment method is applied to evaluate the performance of the GPS ionospheric tomography in detecting ionospheric electron density perturbation at the scale size of around 200 km in wavelength, such as the medium-scale traveling ionospheric disturbances. ©2016 Chen et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0412-6" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Publication Date: 2016-02-19
    Description: The World Digital Anomaly Map (WDMAM) is a worldwide compilation of near-surface magnetic data. We present here a candidate for the second version of the WDMAM and its characteristics. This candidate has been evaluated by a group of independent reviewers and has been adopted as the official second version of the WDMAM during the 26th general assembly of the International Union of Geodesy and Geomagnetism (IUGG). The way this compilation has been built is described with some details. A global magnetic field model of the lithosphere contribution, parameterised by spherical harmonics, has been derived up to degree and order 800. The model information content has been evaluated by computing local spectra. Further, the compatibility of the anomaly field displayed by the WDMAM with a pure induced magnetisation is tested by comparison with the main field strength. These studies allowed an analysis of the compilation in terms of strength and wavelength content. They confirm the extremely smooth and weak contribution of the magnetic field generated in the lithosphere over Western Europe. This apparent weakness possibly extends to the Northern African continent. However, a global analysis remains difficult to achieve given the sparseness of good quality data over very large area of oceans and continents. The WDMAM and related information can be downloaded at http://www.wdmam.org/ . ©2016 Lesur et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0404-6" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Publication Date: 2016-02-18
    Description: The characteristics of aftershock activity of the 2015 Gorkha, Nepal, earthquake (Mw 7.8) were evaluated. The mainshock and aftershocks were recorded continuously by the international Kathmandu strong motion seismographic array operated by Hokkaido University and Tribhuvan University. Full waveform data without saturation for all events enabled us to clarify aftershock locations and decay characteristics. The aftershock distribution was determined using the estimated local velocity structure. The hypocenter distribution in the Kathmandu metropolitan region was well determined and indicated earthquakes located shallower than 12 km depth, suggesting that aftershocks occurred at depths shallower than the Himalayan main thrust fault. Although numerical investigation suggested less resolution for the depth component, the regional aftershock epicentral distribution of the entire focal region clearly indicated earthquakes concentrated in the eastern margin of the major slip region of the mainshock. The calculated modified Omori law’s p value of 1.35 suggests rapid aftershock decay and a possible high temperature structure in the aftershock region. ©2016 Ichiyanagi et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0402-8" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Publication Date: 2016-02-17
    Description: Ionospheric signatures possibly induced by the Nepal earthquake are investigated far outside the epicentral region in Taiwan (~3700 km distance from the epicenter) and in the Czech Republic (~6300 km distance from the epicenter). It is shown that the ionospheric disturbances were caused by long period, ~20 s, infrasound waves that were excited locally by vertical component of the ground surface motion and propagated nearly vertically to the ionosphere. The infrasound waves are heavily damped at the heights of F layer at around 200 km, so their amplitude strongly depends on the altitude of observation. In addition, in the case of continuous Doppler sounding, the value of the Doppler shift depends not only on the advection (up and down motion) of the reflecting layer but also on the compression/rarefaction of the electron gas and hence on the electron density gradient. Consequently, under significant differences of reflection height of sounding radio waves and partly also under large differences in plasma density gradients, the observed ionospheric response at larger distances from the epicenter can be comparable with the ionospheric response observed at shorter distances, although the amplitudes of causative seismic motions differ by more than one order of magnitude. ©2016 Chum et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0401-9" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Publication Date: 2016-02-17
    Description: We herein describe a harmonic Pi2 wave that started at 09:12 UT on August 19, 2010, with data that were obtained simultaneously at 19:00–20:00 MLT by three mid-latitude Asian-Oceanian Super Dual Auroral Radar Network (SuperDARN) radars (Unwin, Tiger, and Hokkaido radars), three Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites (THEMIS A, THEMIS D, and THEMIS E), and ground-based magnetometers at low and high latitudes. All THEMIS satellites, which were located in the plasmasphere, observed Pi2 pulsations dominantly in the magnetic compressional ( B //) and electric azimuthal ( E A) components, i.e., the fast-mode component. The spectrum of Pi2 pulsations in the B // and E A components contained two spectral peaks at approximately 12 to 14 mHz ( f 1, fundamental) and 23 to 25 mHz ( f 2, second harmonic). The Poynting flux derived from the electric and magnetic fields indicated that these pulsations were waves propagating earthward and duskward. Doppler variations ( V ) from the 6-s or 8-s resolution camping beams of the Tiger and Unwin SuperDARN radars, which are associated with Pi2 pulsations in the eastward electric field component in the ionosphere, observed Pi2 pulsations within and near the footprint of the plasmapause, whose location was estimated by the THEMIS satellites. The latitudinal profile of f 2 power normalized by f 1 power for Doppler velocities indicated that the enhancement of the normalized f 2 power was the largest near the plasmapause at an altitude-adjusted corrected geomagnetic (AACGM) latitude of 60° to 65°. Based on these features, we suggest that compressional waves propagate duskward away from the midnight sector, where the harmonic cavity mode is generated. ©2016 Teramoto et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0397-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Publication Date: 2016-02-13
    Description: We investigated the surface texture and chemical compositions of two ~40-μm particles returned from the surface regolith of asteroid Itokawa (RB-DQ04-0062 and RB-DQ04-0091) by the Japan Aerospace Exploration Agency’s Hayabusa mission. We identified splash melts, surface blistering, and many small adhering particles. Seven focused ion beam sections were extracted from both Itokawa particles, targeting one splash melt and ten adhering particles to investigate their composition and provenance and the role of micrometeoroid impacts on Itokawa’s surface. Based on the particle’s structure, mineralogy, and interface between the adhering particle and host grain, we identified lithic fragments and particles deposited by impact. These have morphologies and compositions consistent with impact-generated deposits: two have morphologies and compositions that are consistent with impact-generated silica glass, and one was a Ni-free, metallic Fe, and S-rich assemblage that was likely generated by vapor recondensation during a micrometeoroid impact. This study shows that, even though its regolith is young, micrometeoroid impacts have altered the regolith of asteroid Itokawa. ©2016 Dobrică and Ogliore.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0391-7" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Publication Date: 2016-02-09
    Description: In the southern Kanto region of Japan, where the Philippine Sea plate is descending at the Sagami trough, two different types of large interplate earthquakes have occurred repeatedly. The 1923 (Taisho) and 1703 (Genroku) Kanto earthquakes characterize the first and second types, respectively. A reliable source model has been obtained for the 1923 event from seismological and geodetical data, but not for the 1703 event because we have only historical records and paleo-shoreline data about it. We developed an inversion method to estimate fault slip distribution of interplate repeating earthquakes from paleo-shoreline data on the idea of crustal deformation cycles associated with subduction-zone earthquakes. By applying the inversion method to the present heights of the Genroku and Holocene marine terraces developed along the coasts of the southern Boso and Miura peninsulas, we estimated the fault slip distribution of the 1703 Genroku earthquake as follows. The source region extends along the Sagami trough from the Miura peninsula to the offing of the southern Boso peninsula, which covers the southern two thirds of the source region of the 1923 Kanto earthquake. The coseismic slip takes the maximum of 20 m at the southern tip of the Boso peninsula, and the moment magnitude (Mw) is calculated as 8.2. From the interseismic slip-deficit rates at the plate interface obtained by GPS data inversion, assuming that the total slip deficit is compensated by coseismic slip, we can roughly estimate the average recurrence interval as 350 years for large interplate events of any type and 1400 years for the Genroku-type events. ©2016 Sato et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0395-3" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Publication Date: 2016-01-29
    Description: We discuss different ways to characterize a moment tensor associated with an actual volume change of ΔV C , which has been represented in terms of either the stress glut or the corresponding stress-free volume change ΔV T . Eshelby’s virtual operation provides a conceptual model relating ΔV C to ΔV T and the stress glut, where non-elastic processes such as phase transitions allow ΔV T to be introduced and subsequent elastic deformation of − ΔV T is assumed to produce the stress glut. While it is true that ΔV T correctly represents the moment tensor of an actual volume source with volume change ΔV C , an explanation as to why such an operation relating ΔV C to ΔV T exists has not previously been given. This study presents a comprehensive explanation of the relationship between ΔV C and ΔV T based on the representation theorem. The displacement field is represented using Green’s function, which consists of two integrals over the source surface: one for displacement and the other for traction. Both integrals are necessary for representing volumetric sources, whereas the representation of seismic faults includes only the first term, as the second integral over the two adjacent fault surfaces, across which the traction balances, always vanishes. Therefore, in a seismological framework, the contribution from the second term should be included as an additional surface displacement. We show that the seismic moment tensor of a volume source is directly obtained from the actual state of the displacement and stress at the source without considering any virtual non-elastic operations. A purely mathematical procedure based on the representation theorem enables us to specify the additional imaginary displacement necessary for representing a volume source only by the displacement term, which links ΔV C to ΔV T . It also specifies the additional imaginary stress necessary for representing a moment tensor solely by the traction term, which gives the “stress glut.” The imaginary displacement-stress approach clarifies the mathematical background to the classical theory. ©2016 Ichihara et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0387-3" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Publication Date: 2016-02-01
    Description: The Advanced Land Observing Satellite-2 (ALOS-2, “DAICHI-2”) has been observing Nepal with the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) in response to an emergency request from Sentinel Asia related to the Mw 7.8 Gorkha earthquake on April 25, 2015. PALSAR-2 successfully detected not only avalanches and local crustal displacements but also continental-scale deformation. Especially, by the use of the ScanSAR mode, we are able to make interferograms that cover the entire displacement area of the earthquake. However, we did encounter some fundamental problems with the ScanSAR and incorrect settings of PALSAR-2 operation that have now been fixed. They include (1) burst overlap misalignment between two ScanSAR observations, which limits the number of pairs available and the quality of the interferogram, (2) non-crustal fringes which are derived from co-registration error and/or ionospheric effect and, (3) incorrect setting of the center frequency in the Stripmap beam F2-6. In this paper, we describe their problems and solutions. The number of interferometric pairs are limited by (1) and (3). The accuracy of the interferograms are limited by (2) and (3). The experimental results showed that current solutions for (2) and (3) work appropriately. ©2016 Natsuaki et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0394-4" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Publication Date: 2016-01-28
    Description: In 1255, 1344, and 1408 AD, then again in 1833, 1934, and 2015, large earthquakes, devastated Kathmandu. The 1255 and 1934 surface ruptures have been identified east of the city, along comparable segments of the Main Frontal Thrust (MFT). Whether the other two pairs of events were similar is unclear. Taking into account charcoal’s age inheritance, we revisit the timing of terrace offsets at key sites to compare them with the seismic record since 1200 AD. The location, extent, and moment of the 1833 and 2015 events imply that they released only a small part of the regional slip deficit on a deep thrust segment that stopped north of the Siwaliks. By contrast, the 1344 or 1408 AD earthquake may have ruptured the MFT up to the surface in central Nepal between Kathmandu and Pokhara, east of the surface trace of the great 1505 AD earthquake which affected western Nepal. If so, the whole megathrust system in Nepal broke in a sequence of earthquakes that lasted less than three centuries, with ruptures that propagated up to the surface from east to west. Today’s situation in the Himalayan seismic sequence might be close to that of the fourteenth century. ©2016 Bollinger et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0389-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Publication Date: 2016-01-26
    Description: On 25 April 2015, a large earthquake of Mw 7.8 occurred along the Main Himalayan Thrust fault in central Nepal. It was caused by a collision of the Indian Plate beneath the Eurasian Plate. The epicenter was near the Gorkha region, 80 km northwest of Kathmandu, and the rupture propagated toward east from the epicentral region passing through the sediment-filled Kathmandu Valley. This event resulted in over 8000 fatalities, mostly in Kathmandu and the adjacent districts. We succeeded in observing strong ground motions at our four observation sites (one rock site and three sedimentary sites) in the Kathmandu Valley during this devastating earthquake. While the observed peak ground acceleration values were smaller than the predicted ones that were derived from the use of a ground motion prediction equation, the observed peak ground velocity values were slightly larger than the predicted ones. The ground velocities observed at the rock site (KTP) showed a simple velocity pulse, resulting in monotonic-step displacements associated with the permanent tectonic offset. The vertical ground velocities observed at the sedimentary sites had the same pulse motions that were observed at the rock site. In contrast, the horizontal ground velocities as well as accelerations observed at three sedimentary sites showed long duration with conspicuous long-period oscillations, due to the valley response. The horizontal valley response was characterized by large amplification (about 10) and prolonged oscillations. However, the predominant period and envelope shape of their oscillations differed from site to site, indicating a complicated basin structure. Finally, on the basis of the velocity response spectra, we show that the horizontal long-period oscillations on the sedimentary sites had enough destructive power to damage high-rise buildings with natural periods of 3 to 5 s. ©2016 Takai et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0383-7" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Publication Date: 2016-01-21
    Description: We present a statistical study of medium-scale traveling ionospheric disturbances (MSTIDs) using the Hokkaido East (43.53° N, 143.61° E) and Ekaterinburg (56.42° N, 58.53° E) high-frequency (HF) radar data. Radar datasets are available from 2007 to 2014 for the Hokkaido and from 2013 to 2014 for the Ekaterinburg radar. In the case of the Hokkaido East radar, we have utilized the elevation angle information to study the MSTIDs propagating at the heights of the E and F ionospheric regions separately. We have analyzed the diurnal and seasonal behavior of the following medium-scale traveling ionospheric disturbance (MSTID) parameters: propagation direction, apparent horizontal velocity and wavelength, period, and relative amplitude. The F region MSTID azimuthal patterns were observed to be quite similar by the two radars. The E region northwestward MSTIDs (from 280° to 320°) were typical of summer daytime. Comparison with the horizontal wind model (HWM07) has showed that the dominant MSTID propagation directions match the anti-wind direction well, at least during sunlight hours. We have also found that the wavelength and period tend to decrease with an increase in solar activity. On the contrary, the relative amplitude increases with an increase in solar activity. Moreover, the relative amplitude tends to increase with increasing auroral electrojet (AE) index, as do the wavelength and velocity. ©2016 Oinats et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0390-8" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Publication Date: 2016-01-21
    Description: A novel method has been developed for compound-specific nitrogen isotope compositions with an achiral column which was previously shown to offer high precision for nitrogen isotopic analysis. We applied the method to determine the amino acid contents and stable nitrogen isotopic compositions of individual amino acids from the thermally metamorphosed (above 500 °C) Antarctic carbonaceous chondrites Ivuna-like (CI)1 (or CI-like) Yamato (Y) 980115 and Ornans-like (CO)3.5 Allan Hills (ALH) A77003 with the use of gas chromatography/combustion/isotope ratio mass spectrometry. ALHA77003 was deprived of amino acids due to its extended thermal alteration history. Amino acids were unambiguously identified in Y-980115, and the δ15N values of selected amino acids (glycine +144.8 ‰; α-alanine +121.2 ‰) are clearly extraterrestrial. Y-980115 has experienced an extended period of aqueous alteration as indicated by the presence of hydrous mineral phases. It has also been exposed to at least one post-hydration short-lived thermal metamorphism. Glycine and alanine were possibly produced shortly after the accretion event of the asteroid parent body during the course of an extensive aqueous alteration event and have abstained from the short-term post-aqueous alteration heating due to the heterogeneity of the parent body composition and porosity. These carbonaceous chondrite samples are good analogs that offer important insights into the target asteroid Ryugu of the Hayabusa-2 mission, which is a C-type asteroid likely composed of heterogeneous materials including hydrated and dehydrated minerals. ©2016 Chan et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0382-8" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Publication Date: 2016-01-15
    Description: We used simulation by the reciprocity method to visualize the distribution of Green’s function amplitudes in the source of a megathrust earthquake in the Nankai Trough and considered the effects of various areas (asperities or strong motion generation areas) on the simulated long-period ground motions at Konohana in the Osaka basin. We employed a fault source model proposed for an anticipated M9-class event in the Nankai Trough and the 3D Japan Intergrated Velocity Structure Model developed for simulations of long-period ground motions in Japan. Green’s functions were calculated for about 1400 subsources by combining the finite-difference method and the reciprocity approach. Depths, strikes, and dips of subsources were adjusted to the shape of the upper boundary of the Philippine Sea plate. Ground motions with periods of 4–20 s were considered. The simulated distribution of peak amplitudes of Green’s functions identified two strongly anomalous areas: (1) a large along-strike elongated area just south of the Kii Peninsula and (2) a parallel area closer to the trench. The elongation of the anomalies corresponded well with depth isolines at the top of the Philippine Sea plate. Postulating that plate shape influences simulated ground motions, we investigated the effect on Green’s function amplitudes of phenomena related to plate shape: radiation pattern; variations of medium properties (e.g., velocity and density) at subsource depths; depth, strike, and dip; and the effect of soft sediments. We suggest that the cumulative effect on Green’s function amplitudes of subsource radiation patterns, medium properties at subsource depth, reflection from crustal interfaces, and passage through soft sedimentary layers plays a critical role in the formation of amplitude anomalies. Analysis of waveforms and the time delay of peak amplitude demonstrate that large-amplitude waves of Green’s functions in shallow parts of the plate boundary are composed mostly of surface waves. ©2016 Petukhin et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-016-0385-5" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Publication Date: 2016-01-06
    Description: The flow characteristics and velocities of three landslides in Valles Marineris on Mars are investigated using detailed morphological analyses of high-resolution images and dynamical calculations based on the run-up and curvature of the landslide deposits. The morphologies of the landslides are described, especially concerning those characteristics that can provide information on the dynamics and velocity. The long runout and estimated high velocities, often exceeding 100 m/s, confirm a low basal friction experienced by these landslides. Because subaqueous landslides on Earth exhibit reduced friction, we explore the scenario of sub-lacustrine failures, but find little support to this hypothesis. The environmental conditions that better explain the low friction and the presence of longitudinal furrows suggest an aerial environment with a basal soft and naturally lubricating medium on which friction diminished gradually; in this perspective, ice is the most promising candidate. ©2016 Mazzanti et al.〈br /〉〈br /〉〈a href="http://doi.org/10.1186/s40623-015-0369-x" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1343-8832
    Electronic ISSN: 1880-5981
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Publication Date: 2016-04-01
    Description: Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a characteristic site property. Focusing on nitrogen (N), we hypothesize that this partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. We investigate the nature of this partitioning ratio with three approaches: (1) nutrient stock data from forested ecosystems in North America, (2) a process-based ecosystem model, and (3) conceptual shifts in site nutrient availability with altered disturbance frequency. Partitioning ratios could be applied to a variety of ecosystems and successional states, allowing for improved temporal scaling of disturbance events. The generally short-term empirical evidence for recovery trajectories of nutrient stocks and partitioning ratios suggests two areas for future research. First, we need to recognize and quantify how disturbance effects can be accreting or depleting, depending on whether their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to test how altered disturbance frequencies from the present state may be constructive or destructive in their effects on biogeochemical cycling and nutrient availability. Long-term studies, with repeated sampling of soils and vegetation, will be essential in further developing this framework of biogeochemical response to disturbance. ©2015 Her Majesty the Queen in Right of Canada
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Publication Date: 2016-04-01
    Description: Many ecosystems rely on subsidies of carbon and nutrients from surrounding environments. In headwater streams that are heavily shaded by riparian forests, allochthonous inputs from terrestrial systems often comprise a major part of the organic matter budget. Bacteria play a key role in organic matter cycling in streams, but there is limited evidence about how much bacterial carbon is actually assimilated by invertebrate and fish consumers, and how bacterial carbon assimilation varies among streams. We conducted stable isotope tracer additions of 13C-acetate, that is assimilated only by bacteria, and 15N-ammonium, that is assimilated by both bacteria and algae, in two small, shaded streams in the Adirondack region of New York State, USA. Our goal was to determine whether there is an important trophic link between bacteria and macroconsumers, and whether the link changes when the light environment is experimentally altered. In 2009, we evaluated bacterial carbon use in both streams with natural canopy cover using 10-day dual-isotope tracer releases. The canopy was then thinned in one stream to increase light availability and primary production and tracer experiments were repeated in 2010. As part of the tracer experiments, we developed a respiration assay to measure the δ 13C content of live bacteria, which provided critical information for determining how much of the carbon assimilated by invertebrate consumers is from bacterial sources. Some invertebrate taxa, including scraper mayflies ( Heptagenia spp.) that feed largely on biofilms assimilated over 70% of their carbon from bacterial sources, whereas shredder caddisflies ( Pycnopsyche spp.) that feed on decomposing leaves assimilated less than 1% of their carbon from bacteria. Increased light availability led to strong declines in the magnitude of bacterial carbon fluxes to different consumers (varying from −17 to −91% decrease across invertebrate taxa), suggesting that bacterial energy assimilation differs not only among consumer taxa but also within the same consumer taxa in streams with different ecological contexts. Our results demonstrate that fluxes of bacterial carbon to higher trophic levels in streams can be substantial, that is over 70% for some taxa, but that invertebrate taxa vary considerably in their reliance on bacterial carbon, and that local variation in carbon sources controls how much bacterial carbon invertebrates use. ©2015 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Publication Date: 2016-04-01
    Description: Cyclic phenomena have been the focus of many studies in stressed conifer forests. In these systems, suppressed seedlings are released following the synchronous death of canopy trees. These cycles occur over hundreds of years, and thus studying them in the field is difficult, if not impossible in some cases. This difficulty highlights the advantages of vegetation modeling studies. We used the individual-based gap model, University of Virginia Forest Model Enhanced (UVAFME), to simulate forest dynamics over time at a high-elevation, subalpine forest (dominated by Engelmann spruce and subalpine fir) in southern Wyoming. Following model calibration, UVAFME was validated by running it up an elevation gradient to determine if it could simulate changes in species composition with elevation. UVAFME was then run exclusively at the high-elevation location for periods of 3000 years to simulate long-term forest dynamics at the site. It was found that without the intrusion of exogenous disturbances, the subalpine zone of the Rocky Mountains demonstrates cyclic phenomena, both at the plot scale and the landscape scale. By itself, Engelmann spruce demonstrates a natural periodicity of 300 years, whereas subalpine fir has a natural periodicity of 200 years. In the two-species forest, both species have a periodicity of 300 years. This output corresponds well with field data from similar high-elevation conifer sites. These results, along with other examples of cyclic phenomena in ecological systems, indicate that periodicities in ecosystems may be more common than previously thought, though they may be difficult to distinguish due to disturbances and the time- and space-scales at which they occur. ©2015 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10021-015-9945-y" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Publication Date: 2016-04-01
    Description: Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide ( p CO2) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice p CO2 variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice p CO2 across the 506 lakes_. Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice p CO2. Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice p CO2. Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes. ©2015 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10021-015-9944-z" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Publication Date: 2016-04-01
    Description: How global warming will affect soil respiration ( R _S) and its source components is poorly understood despite its importance for accurate prediction of global carbon (C) cycles. We examined the responses of R _S, heterotrophic respiration ( R _H), autotrophic respiration ( R _A), nitrogen (N) availability, and fine-root biomass to increased temperature in an open-field soil warming experiment. The experiment was conducted in a cool-temperate deciduous forest ecosystem in northern Japan. As this forest is subjected to strong temporal variation in temperature, on scales ranging from daily to seasonal, we also investigated the temporal variation in the effects of soil warming on R _S, R _H, and R _A. Soil temperature was continuously elevated by about 4.0°C from 2007 to 2014 using heating wires buried in the soil, and we measured soil respiratory processes in all four seasons from 2012 to 2014. Soil warming increased annual R _S by 32–45%, but the magnitude of the increase was different between the components: R _H and R _A were also stimulated, and increased by 39–41 and 17–18%, respectively. Soil N availability during the growing season and fine-root biomass were not remarkably affected by the warming treatment. We found that the warming effects varied seasonally. R _H increased significantly throughout the year, but the warming effect showed remarkable seasonal differences, with the maximum stimulation in the spring. This suggests that warmer spring temperature will produce a greater increase in CO2 release than warmer summer temperatures. In addition, we found that soil warming reduced the temperature sensitivity ( Q _10) of R _S. Although the Q _10 of both R _H and R _A tended to be reduced, the decrease in the Q _10 of R _S was caused mainly by a decrease in the response of R _A to warming. These long-term results indicate that a balance between the rapid and large response of soil microbes and the acclimation of plant roots both play important roles in determining the response of R _S to soil warming, and must be carefully considered to predict the responses of soil C dynamics under future temperature conditions. ©2015 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Publication Date: 2016-04-01
    Description: Leachate from litter and vegetation penetrates permafrost surface soils during thaw before being exported to aquatic systems. We know this leachate is critical to ecosystem function downstream and hypothesized that thaw leachate inputs would also drive terrestrial microbial activity and nutrient uptake. However, we recognized two potential endpoint scenarios: vegetation leachate is an important source of C for microbes in thawing soil; or vegetation leachate is irrelevant next to the large background C, N, and P pools in thaw soil solution. We assessed these potential outcomes by making vegetation leachate from frozen vegetation and litter in four Arctic ecosystems that have a variety of litter quality and soil C, N, and P contents; one of these ecosystems included a disturbance recovery chronosequence that allowed us to test our second hypothesis that thaw leachate response would be enhanced in disturbed ecosystems. We added water or vegetation leachate to intact, frozen, winter soil cores and incubated the cores through thaw. We measured soil respiration throughout, and soil solution and microbial biomass C, N, and P pools and gross N mineralization immediately after a thaw incubation (−10 to 2°C) lasting 6 days. Vegetation leachate varied strongly by ecosystem in C, N, and P quantity and stoichiometry. Regardless, all vegetated ecosystems responded to leachate additions at thaw with an increase in the microbial biomass phosphate flush and an increase in soil solution carbon and nitrogen, implying a selective microbial uptake of phosphate from plant and litter leachate at thaw. This response to leachate additions was absent in recently disturbed, exposed mineral soil but otherwise did not differ between disturbed and undisturbed ecosystems. The selective uptake of P by microbes implies either thaw microbial P limitation or thaw microbial P uptake opportunism, and that spring thaw is an important time for P retention in several Arctic ecosystems. ©2015 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10021-015-9947-9" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Publication Date: 2016-04-01
    Description: Forests are major carbon stores on a global scale but there are significant uncertainties about changes in carbon flux through time and the relative contributions of drivers such as land use, climate and atmospheric CO2. We used the dynamic vegetation model LPJ-GUESS to test the relative influence of CO2 increase, temperature increase and management on carbon storage in living biomass in an unmanaged European temperate deciduous forest. The model agreed well with living biomass reconstructed from forest surveys and maximum biomass values from other studies. High-resolution climate data from both historical records and general circulation models were used to force the model and was manipulated for some simulations to allow relative contributions of individual drivers to be assessed. Release from management was the major driver of carbon storage for most of the historical period, whereas CO2 took over as the most important driver in the last 20 years. Relatively, little of the observed historical increase in carbon stocks was attributable to increased temperature. Future simulations using IPCC RCP4.5 and RCP8.5 scenarios indicated that carbon stocks could increase by as much as 3 kg C m−2 by the end of the century, which is likely to be driven by CO2 increase. This study suggests that unmanaged semi-natural woodland in Europe can be a major potential carbon sink that has been previously underestimated. Increasing the area of unmanaged forest would provide carbon sink services during recovery from timber extraction, while long-term protection would ensure carbon stocks are maintained. ©2016 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10021-015-9950-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Publication Date: 2016-03-24
    Description: Although coastal vegetated ecosystems are widely recognised as important sites of long-term carbon (C) storage, substantial spatial variability exists in quantifications of these ‘blue C’ stocks. To better understand the factors behind this variability we investigate the relative importance of geomorphic and vegetation attributes to variability in the belowground C stocks of saltmarshes in New South Wales (NSW), southeast Australia. Based on the analysis of over 140 sediment cores, we report mean C stocks in the surface metre of sediments (mean ± SE = 164.45 ± 8.74 Mg C ha−1) comparable to global datasets. Depth-integrated stocks (0–100 cm) were more than two times higher in fluvial (226.09 ± 12.37 Mg C ha−1) relative to marine (104.54 ± 7.11) geomorphic sites, but did not vary overall between rush and non-rush vegetation structures. More specifically, sediment grain size was a key predictor of C density, which we attribute to the enhanced C preservation capacity of fine sediments and/or the input of stable allochthonous C to predominantly fine-grained, fluvial sites. Although C density decreased significantly with sediment depth in both geomorphic settings, the importance of deep C varied substantially between study sites. Despite modest spatial coverage, NSW saltmarshes currently hold approximately 1.2 million tonnes of C in the surface metre of sediment, although more C may have been returned to the atmosphere through habitat loss over the past approximately 200 years. Our findings highlight the suitability of using sedimentary classification to predict blue C hotspots for targeted conservation and management activities to reverse this trend. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Publication Date: 2016-03-30
    Description: Woody plant demographics provide important insight into ecosystem state-shifts in response to changing fire regimes. In Australian tropical savannas, the switch from patchy landscape burning by Aborigines to unmanaged wildfires within the past century has been implicated in biodiversity declines including the fire-sensitive conifer, Callitris intratropica . C.   intratropica commonly forms small, closed-canopy groves that exclude fire and allow recruitment of conspecifics and other fire-sensitive woody plants. C.   intratropica groves provide a useful indicator of heterogeneity and fire regime change, but the mechanisms driving the species’ persistence and decline remain poorly understood. We examined the hypothesis that C.   intratropica population stability depends upon a regime of frequent, low-intensity fires maintained by Aboriginal management. We combined integral projection models of C.   intratropica population behaviour with an environmental state change matrix to examine how vital rates, grove dynamics and the frequency of high- and low-intensity fires contribute to population stability. Closed-canopy C.   intratropica groves contributed disproportionately to population growth by promoting recruitment, whereas singleton trees accounted for a larger proportion of adult mortality. Our patch-based population model predicted population declines under current fire frequencies and that the recruitment of new groves plays a critical role in the species’ persistence. Our results also indicated that reducing fire intensity, a key outcome of Aboriginal burning, leads to C.   intratropica population persistence even at high fire frequencies. These findings provide insight into the relationship between ecosystem composition and human–fire interactions and the role of fire management in sustaining the mosaics that comprise ‘natural’ systems. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Publication Date: 2016-03-01
    Description: Changes in the seascape often result in altered hydrodynamics that lead to coinciding changes in sediment dynamics. Little is known on how altered sediment dynamics affect long-term seagrass persistence. We studied the thresholds of sediment dynamics in relation to seagrass presence by comparing sediment characteristics and seagrass presence data of seven separate seagrass meadows. All meadows had a long-term (〉20 years) presence. Within these meadows, we distinguish so-called “hotspots” (areas within a meadow where seagrass was found during all mapping campaigns) and “coldspots” (with infrequent seagrass presence). We monitored static sediment characteristics (median grain size, bulk density, silt content) and sediment dynamics (that is, bed level change and maximum sediment disturbance depth), bioturbation (that is, lugworm densities and induced fecal pit and mound relief), and seagrass cover. We statistically analyzed which sediment characteristic best explains seagrass cover. Densely vegetated hotspots were shown to have lower sediment dynamics than sparsely vegetated hotspots and coldspots, whereas static sediment characteristics were similar (grain size, bulk density). The vegetation cover was either low (2–15%) or high (〉30%) and sediment dynamics showed a threshold for vegetation cover. From this correlative finding, we postulate a self-sustaining feedback of relatively dense seagrass via sediment stabilization and accordingly a runaway feedback once the seagrass cover becomes too sparse. The sensitivity for sediment dynamics shown in our study implies that future existence of seagrass meadows may be at risk as ongoing climate change might directly (increased environmental extremes) or indirectly (changing seascapes) negatively affect seagrass beds. ©2015 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10021-015-9932-3" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Publication Date: 2016-03-01
    Description: Ecosystems are generally linked via fluxes of nutrients and energy across their boundaries. For example, freshwater ecosystems in temperate regions may receive significant inputs of terrestrially derived carbon via autumnal leaf litter. This terrestrial particulate organic carbon (POC) is hypothesized to subsidize animal production in lakes, but direct evidence is still lacking. We divided two small eutrophic lakes each into two sections and added isotopically distinct maize litter to the treatment sections to simulate increased terrestrial POC inputs via leaf litter in autumn. We quantified the reliance of aquatic consumers on terrestrial resources (allochthony) in the year subsequent to POC additions by applying mixing models of stable isotopes. We also estimated lake-wide carbon (C) balances to calculate the C flow to the production of the major aquatic consumer groups: benthic macroinvertebrates, crustacean zooplankton, and fish. The sum of secondary production of crustaceans and benthic macroinvertebrates supported by terrestrial POC was higher in the treatment sections of both lakes. In contrast, total secondary and tertiary production (supported by both autochthonous and allochthonous C) was higher in the reference than in the treatment sections of both lakes. Average aquatic consumer allochthony per lake section was 27–40%, although terrestrial POC contributed less than about 10% to total organic C supply to the lakes. The production of aquatic consumers incorporated less than 5% of the total organic C supply in both lakes, indicating a low ecological efficiency. We suggest that the consumption of terrestrial POC by aquatic consumers facilitates a strong coupling with the terrestrial environment. However, the high autochthonous production and the large pool of autochthonous detritus in these nutrient-rich lakes make terrestrial POC quantitatively unimportant for the C flows within food webs. ©2015 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Publication Date: 2016-02-26
    Description: Most fluvial networks worldwide include watercourses that recurrently cease to flow and run dry. The spatial and temporal extent of the dry phase of these temporary watercourses is increasing as a result of global change. Yet, current estimates of carbon emissions from fluvial networks do not consider temporary watercourses when they are dry. We characterized the magnitude and variability of carbon emissions from dry watercourses by measuring the carbon dioxide (CO2) flux from 10 dry streambeds of a fluvial network during the dry period and comparing it to the CO2 flux from the same streambeds during the flowing period and to the CO2 flux from their adjacent upland soils. We also looked for potential drivers regulating the CO2 emissions by examining the main physical and chemical properties of dry streambed sediments and adjacent upland soils. The CO2 efflux from dry streambeds (mean ± SD = 781.4 ± 390.2 mmol m−2 day−1) doubled the CO2 efflux from flowing streambeds (305.6 ± 206.1 mmol m−2 day−1) and was comparable to the CO2 efflux from upland soils (896.1 ± 263.2 mmol m−2 day−1). However, dry streambed sediments and upland soils were physicochemically distinct and differed in the variables regulating their CO2 efflux. Overall, our results indicate that dry streambeds constitute a unique and biogeochemically active habitat that can emit significant amounts of CO2 to the atmosphere. Thus, omitting CO2 emissions from temporary streams when they are dry may overlook the role of a key component of the carbon balance of fluvial networks. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Publication Date: 2016-02-23
    Description: Growing evidence indicates that parasites—when considered—can play influential roles in ecosystem structure and function, highlighting the need to integrate disease ecology and ecosystem science. To strengthen links between these traditionally disparate fields, we identified mechanisms through which parasites can affect ecosystems and used empirical literature searches to explore how commonly such mechanisms have been documented, the ecosystem properties affected, and the types of ecosystems in which they occur. Our results indicate that ecosystem-disease research has remained consistently rare, comprising less than 2% of disease ecology publications. Existing studies from terrestrial, freshwater, and marine systems, however, demonstrate that parasites can strongly affect (1) biogeochemical cycles of water, carbon, nutrients, and trace elements, (2) fluxes of biomass and energy, and (3) temporal ecosystem dynamics including disturbance, succession, and stability. Mechanistically, most studies have demonstrated density-mediated indirect effects, rather than trait-mediated effects, or direct effects of parasites, although whether this is representative remains unclear. Looking forward, we highlight the importance of applying traits-based approaches to predict when parasites are most likely to exert ecosystem-level effects. Future research should include efforts to extend host–parasite studies across levels of ecological organization, large-scale manipulations to experimentally quantify ecosystem roles of parasites, and the integration of parasites and disease into models of ecosystem functioning. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Publication Date: 2016-02-18
    Description: Barrier islands provide the first line of defense against storms for millions of people living in coastal areas. Upland vegetation (that is, grassland, shrubland, and maritime forest) has received little attention, even though this land surface is most strongly affected by development pressures. We use remote-sensing analysis to assess state change on seven undeveloped Virginia barrier islands over 27 years (1984–2011) that are free from direct human influence. Our analysis highlights the spatial–temporally dynamic nature of barrier island upland land area and vegetation, with rapidly changing ecosystem states. Over the time period, upland vegetation was dramatically reduced by 29% whereas woody vegetation cover increased 40% across all islands. Although conversions between sand, grassland, and woody vegetation were variable within each island, three major patterns of vegetative land-cover change were apparent: overall loss of vegetative cover, frequent transitions between grass and woody cover, and gain in woody cover. These patterns are valuable for understanding natural evolution of barrier islands in response to sea-level rise. Evaluation of temporal dynamics in barrier upland is needed to characterize underlying processes including island resilience or chronic stress, and is a prerequisite to sustainable coastal management- and resilience-based planning, especially when implementing ecosystem-based solutions. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Publication Date: 2016-02-01
    Description: We explored tree species diversity effects on soil C stock, C/N ratio, and pH as compared with effects of tree species identity. We sampled forest floors and mineral soil (0–40 cm) in a diversity gradient of 1–5 tree species composed of conifers and broadleaves in Białowieża Forest, Poland. Diversity was a weaker driver than identity of soil C stocks, C/N ratio, and pH in the soil profile. However, there were significant non-additive effects of diversity and significant effects of identity on C stock and C/N ratio within different parts of the soil profile. More diverse forests had higher C stocks and C/N ratios in the 20–40 cm layer, whereas identity in terms of conifer proportion increased C stocks and C/N ratios only in forest floors. A positive relationship between C stocks and root biomass in the 30–40 cm layer suggested that belowground niche complementarity could be a driving mechanism for higher root carbon input and in turn a deeper distribution of C in diverse forests. Diversity and identity affected soil pH in topsoil with positive and negative impacts, respectively. More diverse forests would lead to higher soil nutrient status as reflected by higher topsoil pH, but there was a slight negative effect on N status as indicated by higher C/N ratios in the deeper layers. We conclude that tree species diversity increases soil C stocks and nutrient status to some extent, but tree species identity is a stronger driver of the studied soil properties, particularly in the topsoil. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Publication Date: 2016-01-14
    Description: Arid and semi-arid ecosystems dominated by shrubby species are an important component in the global carbon cycle but are largely under-represented in studies of the effect of climate change on carbon flux. This study synthesizes data from long-term eddy covariance measurements and experiments to assess how changes in ecosystem composition, driven by precipitation patterns, affect inter-annual variability of carbon flux and their components in a halophyte desert community dominated by deep-rooted shrubs (phreatophytes, which depend on groundwater as their primary water source). Our results demonstrated that the carbon balance of this community responded strongly to precipitation variations. Both pre-growing season precipitation and growing season precipitation frequency significantly affected inter-annual variations in ecosystem carbon flux. Heavy pre-growing season precipitation (November–April, mostly as snow) increased annual net ecosystem carbon exchange, by facilitating the growth and carbon assimilation of shallow-rooted annual plants, which used spring and summer precipitation to increase community productivity. Sufficient pre-growing season precipitation led to more germination and growth of shallow-rooted annual plants. When followed by high-frequency growing season precipitation, community productivity of this desert ecosystem was lifted to the level of grassland or forest ecosystems. The long-term observations and experimental results confirmed that precipitation patterns and the herbaceous component were dominant drivers of the carbon dynamics in this phreatophyte-dominated desert ecosystem. This study illustrates the importance of inter-annual variations in climate and ecosystem composition for the carbon flux in arid and semi-arid ecosystems. It also highlights the important effect of changing frequency and seasonal pattern of precipitation on the regional and global carbon cycle in the coming decades. ©2016 Springer Science+Business Media New York
    Print ISSN: 1432-9840
    Electronic ISSN: 1435-0629
    Topics: Biology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Publication Date: 2016-03-01
    Description: Changes in stock location may affect the stability of international fisheries agreements. This paper offers a theoretical analysis of the stability of regional fisheries management organisations (RFMOs) in a non-cooperative, coalition formation game based on the classic Gordon–Schaefer model. We employ a new stability concept which modifies Farsighted Stability (Chwe, J Econ Theory 63:299–325, 1994 ). We call this concept farsighted downwards stability (FDS). We also employ the internal stability (IS) concept for comparison. Analytical results regarding FDS for symmetric players without changing stock location show stable Grand Coalitions for n ≤ 4 player games and the possibility for partial cooperation. Sensitivity analysis deals with changing stock location and cost asymmetry. Stability decreases in n, increases when costs are asymmetric and increases when FDS is employed. Farsighted conjectures on behalf of RFMO members can thus help to maintain cooperation as stock location changes. However, FDS is more sensitive to changes in stock location than IS. ©2014 The Author(s)〈br /〉〈br /〉〈a href="http://doi.org/10.1007/s10640-014-9853-1" target="_blank"〉〈img src="http://bib.telegrafenberg.de/typo3temp/pics/f2f773b55e.png" border="0"〉〈/a〉
    Print ISSN: 0924-6460
    Electronic ISSN: 1573-1502
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Publication Date: 2016-03-01
    Description: In hedonic valuation studies the policy-relevant environmental quality attribute of interest is often costly to measure, especially under pronounced spatial and temporal variability. However, in many cases this attribute affects home prices and consumer preferences solely through its impact on a readily observable, spatially delineated, and time-invariant feature of the physical landscape. We label such a feature a “translating amenity.” We show that under certain conditions changes in the marginal effect of such amenities on home values over time can be used to draw inference on the implicit price of the unobserved environmental quality of interest. We illustrate this approach in the context of a repeat-sales model and the recently intensified outbreak of the Mountain Pine Beetle in the Colorado Front Range. ©2014 Springer Science+Business Media Dordrecht
    Print ISSN: 0924-6460
    Electronic ISSN: 1573-1502
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66