Chronology of the Last Glacial Maximum in the Salzach palaeoglacier area (Eastern Alps)     

Reinhard Starnberger  Helena Rodnight  Christoph Spötl 《第四纪科学杂志》2011,26(5):502-510

A chronostratigraphy based on luminescence data was established at a key loess profile (Duttendorf) in the northern alpine foreland of Austria. The data help to constrain the timing and duration of the Last Glacial Maximum (LGM) in the area of one of the largest east Alpine piedmont glaciers, the Salzach palaeoglacier. Climate deterioration and maximum advance of this glacier were coeval with the beginning of the main loess accumulation phase in the glacier forefield at ～29–30 ka. A late LGM‐outwash gravel layer deposited on top of the loess profile marks the end of the LGM glacier activity at ～20 ka. The geomorphological setting around the loess profile provides evidence of a major glacier oscillation during the course of the LGM, a phenomenon qualitatively known from other alpine palaeoglaciers but never interpreted in terms of palaeoclimate. A LGM glacier oscillation similar to that of the Salzach palaeoglacier was reported recently from the south Alpine Tagliamento palaeoglacier, suggesting a common forcing. The onset of loess deposition at Duttendorf and the tentatively contemporal advance of the Salzach palaeoglacier reflect, as do other data, the drastic cooling in Europe as a result of Heinrich event 3. The first glacier maximum is not well constrained in the study area but a correlation with the better dated Tagliamento amphitheatre suggests a possible response to Heinrich 2. The second re‐advance occurred synchronously (within dating uncertainties) in both palaeoglaciers forefields (at ～21 ka) but the forcing mechanism remains unknown. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The western end of the Eoalpine High‐Pressure Belt (Texel unit,South Tyrol / Italy)          下载免费PDF全文

Hannah Pomella  David Flöss  Romed Speckbacher  Peter Tropper  Bernhard Fügenschuh 《地学学报》2016,28(1):60-69

Eclogites in the Texel Unit (Eastern Alps; South Tyrol, Italy) represent the westernmost outcrops of the E–W striking Eoalpine High‐Pressure Belt (EHB). East of the Tauern Window, the EHB forms part of a Cretaceous intracontinental south‐dipping subduction/collision zone; however, the same nappe stack displays a northwest dip at its western end. This prominent change in dip direction gave rise to discussions on the general setting of the Eoalpine collision. Based on our own observations and literature data, we present a new tectonic model for the western end of the EHB. Due to the special situation of this area at the tip of the Southalpine indenter, originally south(east) dipping structures became overturned, and former thrusts appear as normal faults (e.g. Schneeberg fault zone) while former normal faults presently display thrust geometries (e.g. Jaufen fault). Thus, we explain the current configuration with a coherent Eoalpine subduction direction.  相似文献   

Climate change impacts—throwing the dice?     

Günter Blöschl  Alberto Montanari 《水文研究》2010,24(3):374-381

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Book reviews     

A. Maucher  R. Höll 《Mineralium Deposita》1978,13(2):288-290

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Geochemische Untersuchungen zur Petrographie des Cima d'Asta-Plutons     

P. K. Hörmann  G. Morteani 《Contributions to Mineralogy and Petrology》1966,13(3):181-206

The chemical composition of the various rocks of the Cima d'Asta Intrusion were investigated. On the basis of 29 analyses it is concluded that the granodioritic rocks of the central area of the intrusion belong to the trondhjemitic, leuco-granodioritic and granodioritic magma types, whereas the quartzdioritic rocks of the southwestern border belong to melaquartzdioritic to quartzdioritic magma types. Xenoliths occuring in the top region of the Cima d'Asta massive are chemically and mineralogically identical with the quartzdioritic rocks of the southwestern border.17 biotites separated from various rocks of this area were analysed.On the basis of their octahedral occupancies the biotites of the quartzdioritic rocks and those of the quartzdioritic xenoliths are both akin to the phlogopite-annite series. On the other hand the biotites of the granodioritic rocks are more closely related to the eastonite-siderophyllite series. A notable feature of the phlogopitic biotites is their high content in calcium.The beryllium contents of 82 rocks and of the biotites separated from these rocks substantiate the chemical and mineralogical identity of the quartzdioritic xenoliths with the quartzdioritic border rocks.Because of this identity an ultrametamorphic and possibly hybrid origin of the Cima d'Asta rocks is considered.

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Die Verfasser danken Herrn Prof. Dr. W. v. Engelhardt und Herrn Prof. Dr. F. Karl für wertvolle Hinweise und Diskussionen. Die chemischen Untersuchungen wurden am Mineralogisch-Petrographischen Institut der Universität Tübingen durchgeführt.  相似文献   

Spectral Features of Photon Bubble Models of Ultraluminous X-ray Sources     

Justin D. Finke  Markus Böttcher 《Astrophysics and Space Science》2007,307(1-3):325-327

The nature of Ultraluminous X-ray Sources – X-ray sources which exceed the Eddington luminosity for a ∼10 M _⊙ black hole – remains a mystery. One possible explanation is an inhomogeneous accretion disk around a solar mass black hole where photon transport through radiation-pressure dominated “photon bubbles” can lead to super-Eddington accretion. While previous studies of this model have focused primarily on its radiation-hydrodynamics aspects, here we explore some observational implications of such a model with a Monte Carlo–Fokker Planck radiation transport code.  相似文献   

Verzeichnis der im Institut für allgemeine und angewandte Geologie der Universität München in Angriff genommenen Arbeiten     

Kölbl 《International Journal of Earth Sciences》1936,27(3):307-307

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Particle sedimentation patterns in the eastern Fram Strait during 2000–2005: Results from the Arctic long-term observatory HAUSGARTEN     

Eduard Bauerfeind  Eva-Maria Nöthig  Agnieszka Beszczynska  Kirsten Fahl  Lars Kaleschke  Kathrin Kreker  Michael Klages  Thomas Soltwedel  Christiane Lorenzen  Jan Wegner 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1471-1487

Since 2000 long-term measurements of vertical particle flux have been performed with moored sediment traps at the long-term observatory HAUSGARTEN in the eastern Fram Strait (79°N/4°E). The study area, which is seasonally covered with ice, is located in the confluence zone of the northward flowing warm saline Atlantic water with cold, low salinity water masses of Arctic origin. Current projections suggest that this area is particularly vulnerable to global warming. Total matter fluxes and components thereof (carbonate, particulate organic carbon and nitrogen, biogenic silica, biomarkers) revealed a bimodal seasonal pattern showing elevated sedimentation rates during May/June and August/September. Annual total matter flux (dry weight, DW) at ～300 m depth varied between 13 and 32 g m^?2 a^?1 during 2000 and 2005. Of this total flux 6–13% was due to CaCO₃, 4–21% to refractory particulate organic carbon (POC), and 3–8% to biogenic particulate silica (bPSi). The annual flux of all biogenic components together was almost constant during the period studied (8.5–8.8 g m^?2 a^?1), although this varied from 27% to 67% of the total annual flux. The fraction was lowest in a year characterized by the longest duration of ice coverage (91 and 70 days for the calendar year and summer season, May–September, respectively). Biomarker analyses revealed that organic matter originating from marine sources was present in excess of terrigenious material in the sedimented matter throughout most of the study period. Fluxes of recognizable phyto- and protozooplankton cells amounted up to 60×10⁶ m^?2 d^?1. Diatoms and coccolithophorids were the most abundant organisms. Diatoms, mainly pennate species, dominated during the first years of the investigation. A shift in the composition occurred during the last year when numbers of diatoms declined considerably, leading to a dominance of coccolithoporids. This was also reflected in a decrease in the sedimentation of bPSi. The sedimentation of biogenic matter, however, did not differ from the amount observed during the previous years. Among the larger organisms, pteropods at times contributed significantly to both the total matter and CaCO₃, fluxes.  相似文献   

Single zircon ages and whole-rock Nd isotopic systematics of early Palaeozoic granitoid gneisses from the Czech and Polish Sudetes (Jizerské hory, Krkonoše Mountains and Orlice-Sněžník Complex)     

A. Kröner  P. Jaeckel  E. Hegner  M. Opletal 《International Journal of Earth Sciences》2001,90(2):304-324

Granitoid orthogneisses make up the predominant rock type in the West Sudetes from Jizerské hory in the NW to the Orlické hory and Sn3—ník Mountains in the SE. These generally strongly foliated gneisses are calc-alkaline in composition and display trace element characteristics suggesting generation in a volcanic arc setting. Single zircon ages reflecting the time of emplacement of the gneiss protoliths define a relatively narrow Cambro-Ordovician range between 502 and 515 Ma. This is similar to previously reported zircon ages from the Czech and Polish West Sudetes and documents an important and regionally extensive post-Cadomian magmatic event that we relate to continental arc magmatism on the margin of Avalonia that developed during closure of the Tornquist Ocean. An age of 492 Ma for a microgranite dyke cutting deformed and metamorphosed orthogneisses in the Orlické hory shows the main deformation to be early Paleozoic. Zircon xenocryst minimum ages range between 546 and 2070 Ma and show maxima in the Cadomian/Pan-African (550-850 Ma) and Grenvillian (1000-1300 Ma) time brackets. The Grenvillian event is also evident from Nd mean crustal residence ages that vary between 1.34 and 1.87 Ga. From these data we suggest that the pre-Variscan granitoid gneisses of the Czech West Sudetes were largely generated by melting of a predominantly Grenville-age basement that was part of the northern margin of Gondwana and may have been related to Grenville-age basement now identified in northern South America.  相似文献   

Impact of Ditching in a Small Forested Catchment on Concentrations of Suspended Material, Organic Carbon, Hydrogen Ions and Metals in Stream Water     

Mats Åström  Eeva-Kaarina Aaltonen  Juhani Koivusaari 《Aquatic Geochemistry》2001,7(1):57-73

Stream-water samples were collected during a 4-year-period in twosmall streams, one whose catchment was ditched for forestry halfway through the sampling period and another nearby reference stream whose catchment was not ditched during this period. The main aim was to study the impact of forest ditching on stream-water quality. Whereas the artificial drainage did not change the hydrograph pattern, it had a large effect on stream hydrochemistry: the concentrations of suspended material, Mn, Ca, Mg and Al increased, theconcentrations of total organic carbon decreased, and pH increased by approximately one unit, from an average of 4.4 to 5.4. The increase in suspended material, Mn and Al concentrations is explainedby the physical mobilisation of mineral particulates/colloids from mineral soils (till) exposed on the ditch slopes beneath the peat layer, while the increase in Ca and Mg loads is explained by the release of Ca²⁺ and Mg²⁺ in exchange reactions in this same soil layer. The increase in pH and decrease in TOC concentrations after ditching are related to changes in hydrological flow paths in the catchments, and most likely to immobilisation of both hydrogen ions and humic substances in the near neutral till horizon exposed beneath the peat layer. Only the aquatic abundance of Fewas not significantly affected by the ditching.  相似文献