Early Archean spherule layers from the Barberton Greenstone Belt,South Africa: Mineralogy and geochemistry of the spherule beds in the CT3 drill core          下载免费PDF全文

Seda Ozdemir  Toni Schulz  Christian Koeberl  Wolf Uwe Reimold  Tanja Mohr‐Westheide  Desiree Hoehnel  Ralf Thomas Schmitt 《Meteoritics & planetary science》2017,52(12):2586-2631

Little is known about the Hadean and the Archean impact record on Earth. In the CT3 drill core from the Fig Tree Group of the northern Barberton Greenstone Belt, 17 spherule layer intersections occur, which, provide an outstanding new opportunity to gain insights into meteorite bombardment of the early Earth. CT3 spherules, as primary features, mostly exhibit textural patterns similar to those of the other Barberton spherule layers, but locally mineralogical and chemical compositional differences are observed, likely as a result of various degrees of alteration. The observed mineralogy of the spherule layers is of secondary origin and comprises K‐feldspar, phyllosilicates, carbonates, sulfides, and oxides, with the exception of secondary Ni‐Cr spinel that is of primary origin. Our petrographic investigations suggest alteration by K‐metasomatism, sericitization, silicification, and carbonatization. Siderophile element contents of bulk samples show significant enrichments in Ni (up to 2 wt%) and Ir (up to ~3 ppm), similar to previously studied Archean spherule layers. These values are indicative of the presence of a meteoritic component. On the other hand, lithophile and chalcophile element abundances indicate hydrothermal overprint on the CT3 samples; this may also have influenced the redistribution of the meteoritic component(s). Last, we group the CT3 spherule layers, which occur in three intervals (A, B, and C), according to their petrographic and geochemical features, which indicate evidence for at least three distinct impact events before tectonic overprint that affected the original deposits.  相似文献   

Direct Formation of Burkeite in the Geothermal Waters at Vranjska Banja,Serbia     

Todorović  Bratislav Ž.  Stojiljković  Dragan T.  Pantić  Tanja Petrović  Matović  Branko  Djordjević  Marija Prekajski  Petrović  Sanja M.  Stojiljković  Milena S.  Stevanović  Miloš M. 《Natural Resources Research》2019,28(4):1259-1267

Natural Resources Research - There are no available data about direct burkeite formation on the geothermal waters pipelines in Europe. Data about accompanying minerals of burkeite are also scarce....  相似文献   

40Ar/39Ar and U-Pb dating in the eastern Pilbara,Australia; temporal constraints on structural and metamorphic events between 3.5 and 2.8 Ga (extended abstract)     

Zegers  Tanja E.  Wijbrans  Jan R.  Nelson  Dave R.  White  Stan H. 《Geologie en Mijnbouw》1997,76(4):353-355

Geologie en Mijnbouw -  相似文献   

Fate of Pharmaceuticals During Ground Water Recharge   总被引：4，自引：0，他引：4  

Jörg E. Drewes  Thomas Heberer  Tanja Rauch  Kirsten Reddersen 《Ground Water Monitoring & Remediation》2003,23(3):64-72

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Pesticide Residues in the Danube River Basin in Serbia – a Survey during 2009–2011          下载免费PDF全文

Nikolina Antić  Marina Radišić  Tanja Radović  Tatjana Vasiljević  Svetlana Grujić  Anđelka Petković  Milan Dimkić  Mila Laušević 《洁净——土壤、空气、水》2015,43(2):197-204

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Perspectives in Modelling Climate–Hydrology Interactions     

Stefan Hagemann  Tanja Blome  Fahad Saeed  Tobias Stacke 《Surveys in Geophysics》2014,35(3):739-764

Various land–atmosphere coupling mechanisms exist that may lead to large-scale impacts on climate and hydrology. Some of them are still less understood and not adequately represented in state-of-the-art climate modelling. But, as the current generation of climate models enables consideration and implementation of important coupling processes, the present study provides perspectives for the modelling of relevant climate–hydrology interactions. On a more short-term perspective, these comprise anthropogenic land use and especially irrigation, which has been shown that it may even affect remote regions. On a long-term perspective, the coupling of hydrology to carbon cycle and vegetation becomes important, specifically the dynamics of permafrost and wetlands. Here, we present a review of current knowledge combined with some exemplary studies from a large-scale point of view. Therefore, we focus on climate–hydrology interactions that are relevant on scales utilized in the current or forthcoming global and regional climate modelling exercises.  相似文献   

Distribution of clay minerals in surface sediments of the Aegean Sea: a compilation     

Werner Ehrmann  Gerhard Schmiedl  Yvonne Hamann  Tanja Kuhnt 《International Journal of Earth Sciences》2007,96(4):769-780

Extensive published data sets and some new data on the clay mineral composition of surface sediments in the Aegean Sea, northeastern Mediterranean Sea, have been compiled in order to map the distribution patterns of clay mineral assemblages and to decipher source areas and transport paths. We distinguished six provinces, a Northwest Aegean Province, a Marmara-Dardanelles Province, a West Turkey Province, a Southeast Aegean Province, a Kithira Province and a Central Aegean Province. The clay mineral assemblages in the coastal and shelf areas carry the signature of the riverine sediment discharge from southeast Europe and Turkey, respectively. The southern Aegean Sea is probably influenced by the River Nile discharge and transport of clay minerals by surface currents. The clay minerals in the central Aegean Sea form a mixed assemblage comprising components of the other assemblages. A dispersion and dilution of clay minerals by surface currents is obvious.  相似文献   

From rebel governance to state consolidation – Dynamics of loyalty and the securitisation of the state in Eritrea     

Tanja R. Müller 《Geoforum》2012,43(4):793-803

This paper discusses Eritrea as a contemporary case of state-making grounded in war, a fact that has resulted in the emergence of one of the ‘hardest’ states in sub-Saharan Africa. The state-making process in Eritrea is looked at with a focus on the legacies of liberation movement governance in the changing dynamics of state consolidation from 1993 to this day. Those dynamics are analysed by reverting to Hirsch-man’s categories of ‘loyalty’, ‘exit’ and ‘voice’. Hirschman’s framework is chosen because the category of loyalty and resulting dynamics illuminate particularly well the transitions within the Eritrean state making process.It is shown that the parameters of war that have resulted in the creation of the Eritrean state have led to a particular kind of state characterised by a high degree of loyalty, visible in the propensity of large segments of the population to associate with state activities. Over time and partly based on military defeat in renewed warfare, the exit option has gained prominence particular among the young generation. This has resulted in a drive towards state securitisation combined with measures to make exit a pillar of power consolidation. Those dynamics have not considerably altered the loyalty of Eritrea’s transnational citizenry to the wider project of state consolidation. The paper concludes that state consolidation in Eritrea can thus far be analysed as a successful shift from fostering voice via politics of mobilisation to controlling exit and voice in ways that keep citizens tied to the state project.  相似文献   

Earthquake early warning for transport lines     

Désirée Hilbring  Tanja Titzschkau  Alfons Buchmann  Gottfried Bonn  Friedemann Wenzel  Eberhard Hohnecker 《Natural Hazards》2014,70(3):1795-1825

This paper analyzes the potential of earthquake early-warning systems for transport lines. The interdisciplinary work focuses on rapidly producing an alert map during an ongoing earthquake as well as providing a damage map immediately after the strong-motion phase that visualizes potential damages to the railway infrastructure. In order to meet these application requirements, a service-oriented architecture based on geospatial standards is specified. This ensures the portability of the system architecture to different geographic regions as well as a potential transfer to other natural disasters and infrastructure systems. The first part of the paper describes the standard-based services of the system architecture together with design principles that are useful for the realization of early-warning systems. In the second part of the paper, an online demonstrator for the exemplary test area in the federal state of Baden-Württemberg, Germany, is presented. The system architecture of the demonstrator includes an earthquake early-warning methodology based on artificial neural networks and an infrastructure-specific damage assessment. The third part of the paper analyzes the potential of implementing low-cost sensors in the track, which would provide a dense network directly at the railway infrastructure.  相似文献