Climatically induced lake level changes during the last two millennia as reflected in sediments of Laguna Potrok Aike,southern Patagonia (Santa Cruz,Argentina)   总被引：1，自引：0，他引：1  

Torsten?HaberzettlEmail author  Michael?Fey  Andreas?Lücke  Nora?Maidana  Christoph?Mayr  Christian?Ohlendorf  Frank?Sch?bitz  Gerhard?H.?Schleser  Michael?Wille  Bernd?Zolitschka 《Journal of Paleolimnology》2005,33(3):283-302

The volcanogenic lake Laguna Potrok Aike, Santa Cruz, Argentina, reveals an unprecedented continuous high resolution climatic record for the steppe regions of southern Patagonia. With the applied multi-proxy approach rapid climatic changes before the turn of the first millennium were detected followed by medieval droughts which are intersected by moist and/or cold periods of varying durations and intensities. The total inorganic carbon content was identified as a sensitive lake level indicator. This proxy suggests that during the late Middle Ages (ca. AD 1230–1410) the lake level was rather low representing a signal of the Medieval Climate Anomaly in southeastern Patagonia. At the beginning of the Little Ice Age the lake level rose considerably staying on a high level during the whole period. Subsequently, the lake level lowered again in the course of the 20th century.  相似文献   

Fluid-controlled quartz recovery in granulite as revealed by cathodoluminescence and trace element analysis (Bamble sector,Norway)   总被引：1，自引：0，他引：1  

Alfons?M.?van den KerkhofEmail author  Andreas?Kronz  Klaus?Simon  Torsten?Scherer 《Contributions to Mineralogy and Petrology》2004,146(5):637-652

Dispersed quartz veinlets in Proterozoic enderbitic charnockite from Tromøy, Bamble sector (southern Norway), with Ti-concentrations of mostly 80–180 ppm, produce bright blue cathodoluminescence (CL), against contrasting micro-textures of secondary pure quartz with low CL intensity. The textures comprise grain boundary alteration, healed micro-fractures, patches of secondary quartz, and euhedral quartz nuclei. The secondary quartz locally makes up 50% of the total quartz. Trace element analysis has been done by electron-probe micro-analysis (EPMA), laser-induced coupled plasma mass spectrometry (LA-ICPMS), and additional electron-paramagnetic resonance (EPR) spectroscopy. These studies testify systematic trace element reduction and extensive quartz recovery during retrograde metamorphism. We assume healing of a part of the aqueous fluid inclusions during a late thermal event, possible correlated with Paleozoic magmatic activity in the Oslo-Rift. During final cooling, aqueous fluids were largely retrapped in patches of secondary quartz associated with healed fractures, whereas carbonic inclusions (without secondary quartz) may have survived retrograde metamorphism. The variable but generally high salinity of fluid inclusions is assumed to be in part the result of quartz recovery by which ion concentrations were increased in the percentage range.Editorial Responsibility: J. Touret  相似文献   

Timing of deep convection in the Greenland and Iceland Seas   总被引：7，自引：2，他引：7  

Malmberg  Svend-Aage; Jonsson  Steingrimur 《ICES Journal of Marine Science》1997,54(3):300-309

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Using a hydro-reference ontology to provide improved computer-interpretable semantics for the groundwater markup language (GWML2)     

Torsten Hahmann  Shirly Stephen 《International journal of geographical information science》2018,32(6):1138-1171

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Precise orbit determination based on raw GPS measurements   总被引：1，自引：0，他引：1  

Norbert Zehentner  Torsten Mayer-Gürr 《Journal of Geodesy》2016,90(3):275-286

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Modeling of present-day atmosphere and ocean non-tidal de-aliasing errors for future gravity mission simulations     

Henryk Dobslaw  Inga Bergmann-Wolf  Ehsan Forootan  Christoph Dahle  Torsten Mayer-Gürr  Jürgen Kusche  Frank Flechtner 《Journal of Geodesy》2016,90(5):423-436

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AstroGrid-D: Grid technology for astronomical science     

Harry Enke  Matthias Steinmetz  Hans-Martin Adorf  Alexander Beck-Ratzka  Frank Breitling  Thomas Brüsemeister  Arthur Carlson  Torsten Ensslin  Mikael Högqvist  Iliya Nickelt  Thomas Radke  Alexander Reinefeld  Angelika Reiser  Tobias Scholl  Rainer Spurzem  Jürgen Steinacker  Wolfgang Voges  Joachim Wambsganß  Steve White 《New Astronomy》2011,16(2):79-93

We present status and results of AstroGrid-D, a joint effort of astrophysicists and computer scientists to employ grid technology for scientific applications. AstroGrid-D provides access to a network of distributed machines with a set of commands as well as software interfaces. It allows simple use of computer and storage facilities and to schedule or monitor compute tasks and data management. It is based on the Globus Toolkit middleware (GT4).Chapter 1 describes the context which led to the demand for advanced software solutions in Astrophysics, and we state the goals of the project.We then present characteristic astrophysical applications that have been implemented on AstroGrid-D in chapter 2. We describe simulations of different complexity, compute-intensive calculations running on multiple sites (Section 2.1), and advanced applications for specific scientific purposes (Section 2.2), such as a connection to robotic telescopes (Section 2.2.3). We can show from these examples how grid execution improves e.g. the scientific workflow.Chapter 3 explains the software tools and services that we adapted or newly developed. Section 3.1 is focused on the administrative aspects of the infrastructure, to manage users and monitor activity. Section 3.2 characterises the central components of our architecture: The AstroGrid-D information service to collect and store metadata, a file management system, the data management system, and a job manager for automatic submission of compute tasks.We summarise the successfully established infrastructure in chapter 4, concluding with our future plans to establish AstroGrid-D as a platform of modern e-Astronomy.  相似文献   

Plant-Arthropod Associations from the Lower Miocene of the Most Basin in Northern Bohemia(Czech Republic):A Preliminary Report     

Jakub PROKOP  Torsten WAPPLER  Stanislav KNOR  Zlatko KVAEK 《《地质学报》英文版》2010,84(4)

<正>Terrestrial plants and insects currently account for the majority of the Earth's biodiversity,and approximately half of insect species are herbivores.Thus,insects and plants share ancient associations that date back more than 400 Myr.However,investigations of their past interactions are at the preliminary stages in Western Europe.Herein,we present the first results of our study of various feeding damage based on a dataset of nearly 3500 examined plant specimens from the Lower Miocene of the Lagerstatte Bilina Mine in the Most Basin, Czech Republic.This site provides a unique view of the Neogene freshwater ecosystems.It has long been studied by scientists working in different branches of sedimentology,paleobotany,and paleozoology.The fossils are preserved in three characteristic horizons overlaying the coal seam(Clayey Superseam Horizon,Delta Sandy Horizon,and Lake Clayey Horizon),reflecting paleoenvironmental changes in a short time period of development The trace fossils are classified as functional feeding groups or"guilds",without searching for a direct cause or a recent analog host relation.Approximately 23%of specimens of dicotyledonous plant leaves were found to be damaged and associated with some leaf"morphotypes".Deciduous plant-host taxa,and those with a chartaceous texture typical of riparian habitats,were frequently damaged,such as Populus,recorded with two species Populus zaddachii and Populus populina(57.9%and 31%herbivory levels,respectively),followed by Acer,Alnus,and Carya,averaging almost 30%of damaged leaves/leaflets.There has been evidence of 60 damage types(DT) representing all functional feeding groups recorded at the Bilina Mine,including 12 types of leaf mines and 16 gall- type DT.In total,Lower Miocene of the Lagerstatte Bilina Mine exhibits a high level of external foliage feeding types(23.7%),and a low level of more specialized DT,such as galls(43%)and leaf mines(1%).A broader comparison based on DT of the main sedimentary environments shows significance supporting different biomes by frequency of damage levels and DT diversities.  相似文献   

Multiple sources for mineralizing fluids in the Charmitan gold(-tungsten) mineralization (Uzbekistan)   总被引：1，自引：0，他引：1  

Torsten Graupner  Samuel Niedermann  Dieter Rhede  Ulf Kempe  Reimar Seltmann  C. Terry Williams  Reiner Klemd 《Mineralium Deposita》2010,45(7):667-682

Mineral assemblages present within the Charmitan gold(-tungsten) quartz-vein mineralization have been investigated for their cathodoluminescence behaviour, chemical composition and noble gas isotope systematics. This inventory of methods allows for the first time a systematic reconstruction of the paragenetic relationships of quartz, scheelite, sulphides and native gold within the gold mineralization at Charmitan and provides the basis to utilise noble gas data in the discussion of sources and evolution of ore-forming fluids. The vein quartz is classified into four generations based on microscopic and cathodoluminescence investigations. Quartz I shows intense brittle deformation as associated scheelite I. Undeformed scheelite II overgrows scheelite I and has lower light rare earth element and higher intermediate rare earth element contents as well as higher strontium concentrations. Scheelite II is associated with the economic gold mineralization and formed during re-crystallisation and re-precipitation of material which was partly re-mobilised from early scheelite I during infiltration of gold-bearing fluids. Early stage native gold inclusions are often associated with stage 2 sulphides, scheelite II and bismuth tellurides and contain Ag (3.6–24.4 wt.%), Hg (≤1.0 wt.%) and Bi (≤0.2 wt.%). Later stage electrum grains occur in association with stage 3 sulphides and sulphosalts and contain Hg (<0.8 wt.%) and elevated Sb concentrations (up to 3.0 wt.%). Noble gas isotope data (³He/⁴He: 0.2-0.4 Ra) for hydrothermal ore fluids trapped in the gold-related sulphides and sulphosalts (stage 2 pyrite and arsenopyrite; stage 3 pyrite, sphalerite, galena and lead sulphosalts) suggest that diverse fluid sources were involved in the formation of the Charmitan gold deposit. These data are indicative of a small, but significant input of fluids from external, deep-seated (mantle and possibly lower crust) sources. A decrease in the input of mantle helium and an increasing role of crustal helium from early to later stages of the mineralization is suggested by the measured ³He/⁴He and ⁴⁰Ar*/⁴He ratios. Sulphides from ore veins in meta-sedimentary rocks contain higher portions of meteoric fluids than those in intrusive rock types as indicated by their lower ³He/³⁶Ar ratios. The ³He/³⁶Ar ratios in the meta-sedimentary rocks agree well with ratios typical of gold mineralizations in the Tien Shan gold province completely hosted by meta-sedimentary sequences, indicating intense fluid-wall rock interaction.  相似文献   

New model simulations of the global atmospheric electric circuit driven by thunderstorms and electrified shower clouds: The roles of lightning and sprites     

Michael J. Rycroft  Anna Odzimek  Neil F. Arnold  Martin Füllekrug  Andrzej Ku&#x;ak  Torsten Neubert 《Journal of Atmospheric and Solar》2007,69(17-18):2485

Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit. These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning discharge from the base of a thunderstorm increases the ionospheric potential above the thundercloud by 0.0013%. Assuming the ionosphere to be an equipotential surface, this discharge increases the current flowing in the global circuit and the fair-weather electric field also by 0.0013%. A moderate positive cloud-to-ground lightning discharge from the bottom of a thunderstorm decreases the ionospheric potential by 0.014%. Such a discharge may trigger a sprite, causing the ionospheric potential to decrease by . The time scales for the recovery of the ionospheric potential are shown to be , which is of the same order as the CR time constant for the global circuit. Knowing the global average rate of lightning discharges, it is found that negative cloud-to-ground discharges increase the ionospheric potential by only 4%, and that positive cloud-to-ground discharges reduce it by 3%. Thus, overall, lightning contributes only 1%—an almost insignificant proportion—to maintaining the high potential of the ionosphere. It is concluded that the net upward current to the ionosphere due to lightning is only . Further, it is concluded that conduction and convection currents associated with “batteries” within thunderclouds and electrified shower clouds contribute essentially equally ( each) to maintaining the ionospheric potential.  相似文献