A Carnian 40Ar/39Ar age for the Paasselkä impact structure (SE Finland)—An update          下载免费PDF全文

Winfried H. Schwarz  Martin Schmieder  Elmar Buchner  Mario Trieloff  Jarmo Moilanen  Teemu Öhman 《Meteoritics & planetary science》2015,50(1):135-140

A recrystallized band of pale feldspathic impact melt in a gneissic impact breccia from the approximately 10 km Paasselkä impact structure in southeast Finland was dated via ⁴⁰Ar/³⁹Ar step‐heating. The newly obtained plateau age of 228.7 ± 1.8 (2.2) Ma (2σ) (MSWD = 0.32; p = 0.93) is equal to the previously published pseudoplateau age of 228.7 ± 3.0 (3.4) (2σ) for the impact event. According to the current international chronostratigraphic chart and using the most recent published suggestions for the K decay constants, a Carnian (Late Triassic) age for the Paasselkä impact structure of 231.0 ± 1.8 (2.2) Ma (2σ) is calculated and considered the most precise and accurate age for this impact structure. The new plateau age for Paasselkä confirms the previous dating result but is, based on its internal statistics, much more compelling.  相似文献   

Comment on the “Joint determination of K decay constants and Ar/K for the Fish Canyon sanidine standard, and improved accuracy for Ar/Ar geochronology” by Paul R. Renne et al. (2010)     

Winfried H. Schwarz  Karsten Kossert  Jens Hopp 《Geochimica et cosmochimica acta》2011,75(17):5094-5100

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Eutrophication assessment of the Baltic Sea Protected Areas by available data and GIS technologies     

Ranft S  Pesch R  Schröder W  Boedeker D  Paulomäki H  Fagerli H 《Marine pollution bulletin》2011,63(5-12):209-214

Concerning increased degradation of marine ecosystems, there is a great political and institutional demand for an array of different tools to restore a good environmental status. Thereby, eutrophication is acknowledged as one of the major human induced stressors which has to be monitored and reduced. The present study concentrates on an assessment of the eutrophication status of the Baltic Sea Protected Areas by use of available data and GIS technologies. Two geodata layers were used for analysis: (1) a map on the eutrophication status of the Baltic Sea generated by the Helsinki Commission applying the HELCOM Eutrophication Assessment Tool (HEAT), and (2) modelled data on atmospheric nitrogen deposition made available by the European Monitoring and Evaluation Programme (EMEP). The results yielded comprehensive and conclusive data indicating that most of the BSPAs may be classified as being 'affected by eutrophication' and underlining the need to decrease the overall emissions of nutrients.  相似文献   

Surface water changes in the norwegian sea during last deglacial and holocene times     

Henning A. Bauch  Mara S. Weinelt 《Quaternary Science Reviews》1997,16(10):1115-1124

Stable carbon and oxygen isotopes of the polar planktic foraminifera Neogloboquadrina pachyderma sinistral from sediment cores of the Norwegian Sea reveal several anomalous ¹³C and δ¹⁸O depletions in the surface water during the last glacial to interglacial transition and during the later Holocene. The depletions that are observed between the Last Glacial Maximum (LGM) and the end of the main deglacial phase were caused by massive releases of freshwater from thawing icebergs, which consequently resulted in a stratification of the uppermost surface water layer and a non-equilibrium between the water below and the atmosphere. At ~8.5 ka (¹⁴C BP) this strong iceberg melting activity ceased as defined by the cessation of the deposition of ice-rafted detritus. After this time, the dominant polar and subpolar planktic foraminiferal species rapidly increased in numbers. However, this post-deglacial evolution towards a modern-type oceanographic environment was interupted by a hitherto undescribed isotopic event (~7–8 ka) which, on a regional scale, is only identified in eastern Norwegian Sea surface water. This event may be associated with the final pulse of glacier meltwater release from Fennoscandia, which affected the onset of intensified coastal surface water circulation off Norway during a time of regional sea-level rise. All these data indicate that surface water changes are an integral part of deglacial processes in general. Yet, the youngest observed change noted around 3 ka gives evidence that such events with similar effects occur even during the later Holocene when from a climatic point of view relativelystable conditions prevailed.  相似文献   

Aluminous granulites from the Pulur complex, NE Turkey: a case of partial melting, efficient melt extraction and crystallisation     

Gültekin Topuz  Rainer Altherr  Angelika Kalt  Muharrem Sat&#x;r  Olaf Werner  Winfried H. Schwarz 《Lithos》2004,72(3-4):183-207

In the Pulur complex, NE Turkey, a heterogeneous rock sequence ranging from quartz-rich mesocratic gneisses to silica- and alkali-deficient, Fe-, Mg- and Al-rich melanocratic rocks is characterized by granulite-facies assemblages involving garnet, cordierite, sillimanite, ilmenite, ±spinel, ±plagioclase, ±quartz, ±biotite, ±corundum, rutile and monazite. Textural evidence for partial melting in the aluminous granulites, particularly leucosomes, is largely absent or strongly obliterated by a late-stage hydrothermal overprint. However, inclusion relations, high peak P–T conditions, the refractory modes, bulk and biotite compositions of the melanocratic rocks strongly support a model of partial melting. The melt was almost completely removed from the melanocratic rocks and crystallised within the adjacent mesocratic gneisses which are silica-rich, bear evidence of former feldspar and show a large range in major element concentrations as well as a negative correlation of most elements with SiO₂. Peak conditions are estimated to be ≥800 °C and 0.7–0.8 GPa. Subsequent near-isothermal decompression to 0.4–0.5 GPa at 800–730 °C is suggested by the formation of cordierite coronas and cordierite–spinel symplectites around garnet and in the matrix. Sm–Nd, Rb–Sr and ⁴⁰Ar/³⁹Ar isotope data indicate peak conditions at 330 Ma and cooling below 300 °C at 310 Ma.  相似文献   

Integrative Monitoring Analysis Aiming at the Detection of Spatial and Temporal Trends of Metal Accumulation in Mosses     

Winfried Schröder  Roland Pesch 《Journal of Atmospheric Chemistry》2004,49(1-3):23-38

Goal and Scope. The UNECE heavy metals in Mosses Surveys provide data on the accumulation of metals in naturally growing mosses throughout Europe. Using Germany as an example, this article concentrates on the elaboration and application of methods of data analysis that are necessary for a comprehensive interpretation of spatial and temporal trends in metal accumulation.Methods and Results. The sampling of mosses, and the chemical analysis of Cr, Cu, Fe, Ni, Pb, Ti, V and Zn in 1990, 1995 and 2000 are summarized briefly. The variogram analyses detect distinct autocorrelation structures in the sample data which may consequently be estimated for all sites in Germany without monitoring metal accumulation by means of ordinary kriging. A procedure for the geostatistical detection of spatial outliers was developed and applied and, after the elimination of the spatial outliers, several measurements were seen to indicate an adequate quality of the geostatistical estimations. The cluster analyses of the z-transformed estimation data result in a nominal multi-element index that indicates regional metal accumulation types over time. Percentile statistics serve for computation of an ordinal, scaled, multi-element accumulation index which is spatially differentiated over time in terms of multivariate, statistically defined ecoregions. The integrative statistical analysis reveals, from 1990 to 2000, that the metal accumulation declines up to 80% in some of the ecoregions. Hot spots of metal accumulation are mapped and interpreted by means of metadata analysis.Conclusions. Dot maps depict the spatial structure of the metal accumulation without spatial bias. This information, detailed with respect to metal species and space, should be generalized for better supporting the interpretation. The combination of geostatistical analysis and estimation, percentile and multivariate statistics is suitable for the calculation of indices that serve for a comprehensive mapping of metal accumulation in the ecoregions over time, for quantifying the bias of the surface estimation, and for mapping spatial outliers and hot spots of metal accumulation.  相似文献   

Die Bedeutung der Diagenese für die Bildung und Ausbeutung von Erdöl- und Erdgaslagerstätten     

Dr. Winfried Zimmerle 《International Journal of Earth Sciences》1979,68(3):1184-1209

Zusammenfassung Nach einem kurzen überblick über die Entwicklung der Diagenese-Forschung in Sandsteinen sind die wichtigsten Prozesse der Sandstein-Diagenese aufgezählt. Moderne Untersuchungsmethoden wie Massenspektroskopie, Elektronen-Mikrosonde, Raster-Elektronenmikroskop, Fluoreszenzmikroskopie, Kathodenlumineszenz und geochemische Analyse der Porenwässer finden kurz Erwähnung. Probleme der Diagenese sind am Beispiel von produktiven Sandsteinhorizonten aus dem Ober-Karbon, dem Unter-Perm (Ober-Rotliegend), dem Mittel-Jura (Dogger) und der Unter-Kreide in der Bundesrepublik Deutschland aufgezeigt. Rasterelektronenmikroskopische Photographien des Porenraumes der verschiedenen Sandsteine und graphische Darstellungen verdeutlichen die Unterschiede der Porenkonfiguration und ihren Einfluß auf die gesteinsphysikalischen Parameter wie Porosität, Permeabilität und Innere Oberfläche in Abhängigkeit vom Grad der Diagenese und vom geologischen Alter. Die Einflüsse der verschiedenen Diagenese-Prozesse auf Porosität, Permeabilität und Innere Oberfläche von Sandsteinen sind tabellarisch zusammengestellt. Ferner erwähnt ist ein allgemeines Modell der Sandstein-Zementation. Künftig wird man immer mehr auf diagenetische Erdöl- und Erdgas-Fallen prospektieren. So gewinnt die Diagenese zunehmend an Bedeutung für die Suche nach Erdöl- und Erdgaslagerstätten und deren Ausbeutung.

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The history of research in sandstone diagenesis is briefly reviewed and the important diagenetic processes are listed. Modern tools in the research of diagenesis are mass spectroscopy, electron microprobe, scanning electronmicroscope, fluorescence microscope, cathodoluminescence, and the geochemical analysis of brines. Main problems of sandstone diagenesis are discussed based on examples from the Pennsylvanian (Upper Carboniferous), Lower Permian (Rotliegend), Middle Jurassic (Dogger), and Lower Cretaceous (Wealden and Valanginian) of the Federal Republic of Germany. Scanning electronmicrographs and graphs demonstrate differences in pore configuration and their influence upon petrophysical parameters such as porosity, permeability, and internal surface in dépendance on the geological age. The influence of various diagenetic processes, in general, on porosity, permeability, and internal surface of sandstone are tabulated. Moreover, a general model of sandstone cementation is presented. In the future the search for diagenetic oil and gas traps will augment. Thus, diagenesis will increasingly gain importance for the exploration and recovery of oil and gas.

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Résumé L'histoire de la recherche de la diagenèse des grès est brièvement passée en revue et les processus les plus importants de la diagenèse sont énumérés.Les méthodes de recherche modernes et l'appareillage approprié comprenant la spectroscopie de masse, la microsonde électronique, la microscopie électronique à balayage, la microscopie à fluorescence, la cathodoluminescence et l'analyse chimique des eaux interstitielles des pores sont brièvement discutées.Les problèmes les plus importants de la diagenèse des grès sont énumérés en se référant à quelques exemples de la République Fédérale Allemande, notamment des horizons gréseux productifs du Carbonifère supérieur, du Permien inférieur (Rotliegend supérieur), du Jurassique moyen (Dogger) et du Crétacé inférieur.Des photographies de pores de différents grès, prises au microscope électronique à balayage, ainsi que des figures schématiques montrent les différentes configurations possibles des pores et mettent en lumière l'influence de ces configurations sur les paramètres pétrophysiques tels que la porosité, la perméabilité et la surface interne des cavités des pores dans leur dépendance vis-à-vis de la diagenèse et de l'âge géologique de la roche.L'influence des différents processus diagénétiques sur la porosité, la perméabilité et la surface interne des grès a été consignée sous forme de tableau.En outre un modèle est présenté pour expliquer la cimentation des grès en général.Il est à prévoir que l'importance de la prospection des pièges diagénétiques de pétrole et de gaz s'accroÎtra.De ce fait on peut conclure que le phénomène de la diagenèse deviendra de plus en plus important dans l'exploration et la production des hydrocarbures.

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Vortrag gehalten anläßlich der 69. Jahrestagung der Geologischen Vereinigung in Heidelberg vom 22.–24. Februar 1979, die das Rahmen-Thema Diagenese zum Inhalt hatte.  相似文献   

运用碳稳定同位素进行底栖生物组合环境古盐度的比较研究     

阴家润 Fues.  FT 《现代地质》1994,8(4):380-392

从葡萄牙卢西塔尼亚盆地侏罗纪生物底栖组合的化石中选取了５４件样品用作碳稳定同位素成分测试，分析其古盐度。按这种方法所恢复的古盐度数据和按底栖组合分析所得到的古盐度能够较好地吻合，由此可作下列结论：（１）尽管化石壳体的原始稳定同位素值可能会受到成岩作用、生物效应、温度差异等因素的影响，但碳稳定同位素值与氧同位素值相比，其重结晶作用产生的成岩影响很小，生物效应却是非常明显地表现于双壳类壳顶区和壳缘的碳同位素值的差异。（２）碳同位素的古盐度表明，葡萄牙卢酉塔尼亚盆地在侏罗纪时曾是一半咸水海湾，其水体含盐度低于２４‰。，所以生物组合中以机会种和半咸水地方性种占优势。（３）机会种分布于中盐至高半咸水的盐区域，而大部分地方性半咸水种局限于中盐度域．（４）卢西塔尼亚盆地晚侏罗世的牡蛎类生存于真盐和高半成水域，定量的盐度研究可能提供牡蛎类自中生代以来对盐度的适应演化。（５）卢西塔尼亚盆地晚侏罗世双壳类虽然属于半咸水属种，但仍然具有厚壳体大的特征。  相似文献   

Petrologische Untersuchungen der mineralfaziellen Zustandsbedingungen im SW-Teil der Münchberger Gneismasse     

Winfried Weinelt 《Mineralogy and Petrology》1958,6(4):281-375

Ohne ZusammenfassungMit 37 TextabbildungenVorliegende Arbeit wurde im Jahre 1955 als Dissertation beim Mineralogisch-Geologischen Institut der Universität Würzburg eingereicht.  相似文献   

Land-cover classification and analysis of change using machine-learning classifiers and multi-temporal remote sensing imagery   总被引：1，自引：0，他引：1  

Hamidreza Keshtkar  Winfried Voigt  Esmaeil Alizadeh 《Arabian Journal of Geosciences》2017,10(6):154

Frequent human activity and rapid urbanization have led to an assortment of environmental issues. Monitoring land-cover change is critical to efficient environmental management and urban planning. The current study had two objectives. The first was to compare pixel-based random forest (RF) and decision tree (DT) classifier methods and a support vector machine (SVM) algorithm both in pixel-based and object-based approaches for classification of land-cover in a heterogeneous landscape for 2010. The second was to examine spatio-temporal land-cover change over the last two decades (1990–2010) using Landsat data. This study found that the object-based SVM classifier is the most accurate with an overall classification accuracy of 93.54% and a kappa value of 0.88. A post-classification change detection algorithm was used to determine the trend of change between land-cover classes. The most significant change from 1990 to 2010 was caused by the expansion of built-up areas. In addition to the net changes, the rate of annual change for each phenomenon was calculated to obtain a better understanding of the process of change. Between 1990 and 2010, an average of 4.53% of lands turned to the built-up annually and there was an annual decrease of about 0.81% in natural land. If the current trend of change continues, regardless of the actions of sustainable development, drastic declines in natural areas will ensue. The results of this study can be a valuable baseline for land-cover managers in the region to better understand the current situation and adopt appropriate strategies for management of land-cover.  相似文献