Denman 002: A new CV3 chondrite from South Australia     

B. Dominik  F. Bussy 《Meteoritics & planetary science》1994,29(3):409-410

Abstract— Denman 002 is a new Australian carbonaceous chondrite. A single stone of 30 g was recovered in 1991 May near Fisher Station on the Trans Australian Railway, Nullarbor Plain, South Australia (30°36′S, 130°04′E). Texture, mineral and chemical composition indicate that it is a CV3 chondrite of oxidised subgroup with several similarities to Allende. It is composed of sharply defined chondrules, Ca-Al rich inclusions up to 3.5 mm across, olivine aggregates and fine-grained, nearly opaque matrix (40 vol%). Silicates are compositionally highly heterogeneous (olivine Fa: 0.2–45.6 mol%, PMD: 109.7). Denman 002 shows shock effects of stage SI and weathering of category A.  相似文献   

Conversion of carbonaceous material to graphite within the Greywacke Zone of the Eastern Alps   总被引：1，自引：0，他引：1  

Gerd?RantitschEmail author  Werner?Grogger  Christian?Teichert  Fritz?Ebner  Christian?Hofer  Eva-Maria?Maurer  Bernhard?Schaffer  Michael?Toth 《International Journal of Earth Sciences》2004,93(6):959-973

Morphology and reflectance of carbonaceous material (CM) in Late Carboniferous metasediments of the eastern Greywacke Zone (Eastern Alps) indicate a mixture of vitrinite, grainy textured and lamellar shaped particles. As imaged by high-resolution atomic-force microscopy, vitrinite and the grainy textured particles show mesophase structures which can be described as facetted nanocrystals within the carbon matrix. High-resolution transmission electron microscopy has revealed two types of microtextures representing different degrees of graphitization. The first type is characterized by elongated ring-shaped microtextures, whereas the second type is characterized by graphite lamellae and polygonal flakes with long-range ordered aromatic layers. In spite of the heterogeneity of the CMs, the geographical distribution of quantitative metamorphic parameter (Raman spectra parameter, X-ray diffraction pattern, microscopic reflectance) suggests a graphitization process which is promoted by advective heat transport during post-collisional processes. In a tentative pressure-time path, Late Cretaceous thrusting results in a turbostratic ordering of the aromatic layer. Ordering to long-range ordered aromatic layers was achieved during the Late Cretaceous-Paleogene exhumation of mid-crustal rocks beneath the eastern Greywacke Zone.  相似文献   

Towards a knowledge base to support geoprocessing workflow development     

Barbara Hofer  Stephan Mäs  Johannes Brauner  Lars Bernard 《International journal of geographical information science》2017,31(4):694-716

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Local Multiscale Approximations of Geostrophic Oceanic Flow: Theoretical Background and Aspects of Scientific Computing     

Willi Freeden  Dominik Michel  Volker Michel 《Marine Geodesy》2005,28(4):313-329

In modern geoscience, understanding the climate depends on the information about the oceans. Covering two-thirds of the Earth, oceans play an important role. Oceanic phenomena are, for example: oceanic circulation; water exchanges between atmosphere, land, and ocean; or temporal changes of the total water volume. All these features require new methods in constructive approximation, since they are regionally bounded and not globally observable. This article deals with a new and alternative method of handling data with locally supported basis functions, modeling them in a multiscale scheme involving a wavelet approximation and presenting the main results for the dynamic topography and the geostrophic flow, e.g., in the Northern Atlantic. Further, it is demonstrated that compressional rates of the occurring wavelet transforms can be achieved by using of locally supported wavelets and investigating the signal distribution within different frequency bands.  相似文献   

Projected robust shift of climate zones over West Africa in response to anthropogenic climate change for the late 21st century   总被引：1，自引：0，他引：1  

Mouhamadou Bamba Sylla  Nellie Elguindi  Filippo Giorgi  Dominik Wisser 《Climatic change》2016,134(1-2):241-253

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Texture and sedimentation rates in Lake Geneva     

J. -P. Vernet  J. Dominik  P. Y. Favarger 《Environmental Geology》1983,5(3):143-149

Thirty two cores were collected from Lake Geneva sediments along one longitudinal and eight transverse profiles. Rates of sedimentation determined by¹³⁷Cs vary from 0.01 to 1.86 g cm⁻² y⁻¹. The average deposition rates in coastal and slope areas amounts to 0.37 g cm⁻² y⁻¹ in the Upper Lake (Grand Lac) and 0.12 g cm⁻² y⁻¹ in the Lower Lake (Petit Lac). In the deep basins, average rates of 0.13 and 0.05 g cm⁻² y⁻¹ were found for the Grand Lac and Petit Lac, respectively. The estimated mass of sediment deposited yearly outside of the principal deltas and turbidity current depositional areas is about 1.0 million tons (about 13% of the estimated total river load). One turbidite is clearly identified in the deepest, central lake area. There is little variation of surface sediment texture (mean grain size about 8–9μm) with the exception of delta areas. Since the beginning of the twentieth century, both carbonate and organic matter have increased as a result of lake eutrophication.  相似文献   

Zur Chronologie anthropogener Schwermetalle in den Sedimenten des Attersees (Österreich)     

Prof. Dr. German Müller  J. Dominik  H. G. Schröder  J. Schneider 《Mineralogy and Petrology》1983,31(3-4):193-206

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Sedimentation rate variations and anthropogenic metal fluxes into Lake Constance sediments     

J. Dominik  A. Mangini  F. Prosi 《Environmental Geology》1983,5(3):151-157

Sedimentation rates were determined by²¹⁰Pb in three sediment cores from the main basin of Lake Constance. Rates vary from 0.094 to 0.133 g cm^?2y^?1, in agreement with previous determinations. A constant radionuclide flux (CR) model reveals long-term, quasi-synchronous fluctuations of sedimentation rate on the basin-wide scale. On average, the rate of sedimentation remains much the same from the beginning of this century indicating little effect of human activity in the watershed on fine-silt sediment supply. The anthropogenic fluxes of Zn, Pb, and Cd in the three cores are compared and the application of²¹⁰Pb as a heavy metal tracer in Lake Constance is examined. It seems to be a very good tracer for Pb, moderately good for Zn and Cu, and not useful for Cd.  相似文献   

Seasonal delivery of the particulate forms of phosphorus to Lake Geneva from the upper Rhone river   总被引：1，自引：0，他引：1  

D. Burrus  R. L. Thomas  J. Dominik  J. P. Vernet 《Aquatic Sciences - Research Across Boundaries》1990,52(3):221-235

Large volume water samples were taken at Porte du Scex and Bouveret at the mouth of the Upper Rhone River as it enters Lake Geneva. Samples were taken every two weeks during 1982 up until August 1983. Water samples were analyzed for total phosphorus (TP), and soluble reactive phosphorus (SRP) and were centrifuged in the field using a continuous flow centrifuge to recover the suspended solids following sieving at 63 µm. The < 63 µm solids were analyzed for total particulate phosphorus (TPP), organic phosphorus (OP), apatite phosphorus (AP) and non apatite inorganic phosphorus (NAIP). The > 63 µm were similarly analyzed and the weight of total solids in both size fractions recorded. Results were compared throughout the period of record to the hydrograph situated at Porte de Scex. The annual cycle of the Rhone can be divided into a low turbidity, low flow winter period (SED 1) and high flow, high turbidity summer season designated (SED 2). Turbidity is well related to discharge. The > 63 µm sediment is mobilized at 200 m³ s^–1 and thereafter increases in concert with, though at a faster rate than, the < 63 µm fraction. The coarse fraction contains significant quantities of phosphorus and in 1982 accounted for 26% of the TPP loading. OP and NAIP are higher in SED 1 than in SED 2 though AP remains constant throughout the year. OP is believed to be driven primarily from point sources whereas NAIP, in addition to point sources, has secondary sources in spring and summer due to sheet erosion from the agricultural soils of the valley. Loadings of phosphorus were calculated by four methods which showed internal consistency though they were higher than previous estimates. Bioavailable phosphorus (BAP) was estimated to account for some 20% of the total phosphorus loading of some 1500 tonnes; BAP is here taken to be the sum of SRP and NAIP and is that portion of the phosphorus load believed to be available to generate phytoplankton growth.  相似文献   

Radioisotopic evidence of perturbations of recent sedimentary record in lakes: a word of caution for climate studies     

Janusz Dominik  Jean-Luc Loizeau  Daniel Span 《Climate Dynamics》1992,6(3-4):145-152

The rate of climatic change estimated from the gradient of signals recorded in lake sediments may be erroneous if post-depositional perturbations are overlooked. A smear out of a pulse signal, over a variable thickness of core section, due to physical or biological mixing, is a well known phenomena. Much less attention is paid to a possible overestimation of the rate of change when a part of record is missing due to an erosion event. In this paper we show a few examples of recent lake sediment perturbations and the resulting distortions in the time scale, as documented by short-lived radionuclides.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program  相似文献