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41.
Ulrich Kramm 《Contributions to Mineralogy and Petrology》1973,41(2):179-196
The Southern Venn-Stavelot Massif is characterized by Ordovician and Devonian rocks very rich in manganese and aluminum, which
are attacked by a low grade regional metamorphism. The assemblages 1 (phengite, paragonite, chlorite, chloritoid, garnet,
quartz, hematite, rutile) and 2 (phengite, paragonite, chlorite, kaolinite (andalusite, pyrophyllite), garnet, quartz, hematite,
rutile) are of basic interest for the formation of chloritoid. As the two rock types are isofaciell and quasi-identical in
chemistry except for the iron oxides, there is clear evidence for the influence of
on the chloritoid formation at its lower p-T stability limit. This can be shown by a discussion of the phase relations of chloritoid, garnet, kaolinite, chlorite and
phengite in respect to the oxidation ratio mol 2 Fe2O3x 100/2 Fe2O3+ FeO of the host rocks. Especially chloritoid and chlorite change their chemistry in a characteristic way with rising oxidation
ratio in getting richer and richer in manganese and magnesium (chloritoid) and magnesium (chlorite). A simultaneous increase
in trivalent iron in these phases is supposed. At an oxidation ratio of 85–90 the
stability limit of chloritoid is reached. The increasing substitution of manganese and magnesium up to this limit should
have a stabilizing effect. In a rough estimate the oxygen partial pressure is supposed to be in the order of 10−10 atm at the stability limit of chloritoid assuming a temperature of metamorphism between 360–400° C. Rocks with oxidation
ratios between 90 and 100 are characterized by the presence of kaolinite. If the oxidation ratio is still higher (all iron
as Fe3+, parts of the manganese in the trivalent state), the rocks belong to assemblage 3 (phengite, paragonite, chlorite, viridine,
(kaolinite), (garnet), quartz, hematite, braunite, rutile).
Dedicated to Prof. Dr. K. Jasmund at his 60. birthday. 相似文献
42.
Ulrich Förstner 《Contributions to Mineralogy and Petrology》1967,15(4):281-308
Zusammenfassung In den Bohrungen Deiningen (D.) und Wörnitzostheim (W.) im Nördlinger Ries wurde unter tertiären Seesedimenten eine 40 m bzw. 70 m mächtige Suevitabfolge aufgeschlossen. Diese Breccie, bestehend aus zertrümmertem kristallinem Grundgebirge mit verschiedenen Anzeichen einer Stoßwellenmetamorphose und aus Glasbomben, wurde mineralogisch und petrographisch untersucht.Korngrößenanalysen zeigen in beiden Profilen eine allmähliche Zunahme des Mediandurchmessers von oben nach unten (D.: 0,1···0,4 mm; W.: 1···6 mm). Die Kornverteilungskurve von W. ist bimodal; das Hauptmaximum wird überwiegend aus grobkörnigen Gesteinsgläsern gebildet, ein kleineres Maximum liegt bei 0,2–0,6 mm und enthält bevorzugt Grundgebirgseinschlüsse.Das Verhältnis von Gesteinsgläsern: Kristallinkomponenten beträgt in D. etwa 30 70, in W. 60 40. Der Suevit von W. enthält durchschnittlich 28% Porenraum und 1–2% Neubildungen; seine Glassubstanz ist überwiegend frisch. Im Suevit von D. sind die Gläser sekundär zersetzt und bedingen höhere Porenvolumina (34–36%) und eine stärkere Verwitterungsneubildung (6–10%; Montmorillonit, Montmorillonit-Illit-Wechsellagerung, Karbonate und Analcim).Einzelminerale in der Kornfraktion 0,063–0,125 mm verteilen sich bei den Leicht-mineralen (d<2,96 g/cm3; Neubildungen nicht berücksichtigt) auf Feldspäte (D.: 56%; W.: 44%), Quarz (D.: 32%; W.: 28%), Biotit (D.: 5%; W.: <1%), Hornblende (D.: 2%; W.: -) und Gläser (D.: 3%; W.: 27%); der Anteil der Schwerminerale beträgt in D. 3–4% (Biotit, Opakes — Hornblende, Granat, Turmalin), in W. 0,5–0,8% (Opakes, Zirkon — Biotit, Rutil).Die chemische Zusammensetzung der Suevit- und Glasproben von W. ist dem granodioritischen Magmentyp ähnlich; die Suevitproben von D. weisen höhere Alkaligehalte auf.
Meinem verehrten Lehrer, Herrn Prof. Dr. W. v. Engelhardt, danke ich für die Überlassung des Themas und alle Förderung meiner Arbeit. Für fördernden Rat danke ich ferner den Herren Dr. F. Lippmann und Dr. D. Stöffler.
Der Deutschen Erdöl AG, insbesondere Herrn Prof. Dr. F. Hecht, danke ich für die Überlassung der Bohrkerne von Deiningen.
Der Deutschen Forschungsgemeinschaft danke ich für die finanzielle Unterstützung dieser Arbeit. 相似文献
Underlying miocene lake sediments, suevite was found in the drill holes of Deiningen (D.) and Wörnitzostheim (W.), 40 meters and 70 meters thick, respectively. This breccia, containing glass and shattered crystalline rocks, in different stages of shock metamorphism, was examined by mineralogical and petrographical methods.In the two suevite profiles medians of grain size distributions gradually increase from top to bottom (D.: 0,1···0,4 mm; W.: 1···6 mm). The grain size distributions of W. are bimodal; the first maximum is mainly formed by coarse grained glass, the second (smaller) maximum (0,2···0,6 mm) contains crystalline components. The ratio of melted rocks: crystalline components is 3070 at D. and 6040 at W. Suevite from the latter locality has a total porosity of 28% (average) and contains 1–2% autigenic minerals; the glasses are mostly fresh. In the D. suevite decomposition of the glass has produced higher porosities (34–36%) and more autigenic minerals (6–10%: montmorillonite, mixed-layer minerals montmorillonite-illite, carbonates, analcime).Mineral composition was determined for the grain sizes from 0,063 to 0,125 mm. The light minerals (d<2,96 g/cm3, without autigenic minerals) comprise: feldspars (D.: 56%; W.: 44%), quartz (D.: 32%; W.: 28%), biotite (D.: 5%; W.: < 1%), hornblende (D.: 2%; W.: -) and glass (D.: 3%; W.: 27%); heavy-mineral content is 3–4% at D. (biotite, opaque minerals — hornblende, garnet, tourmaline) and 0,5–0,8% at W. (opaque minerals, zircon — biotite, rutile).The chemical composition of suevite and glass samples from W. is similar to granodiorite type rock. The suevite of D. contains more potassium and sodium.
Meinem verehrten Lehrer, Herrn Prof. Dr. W. v. Engelhardt, danke ich für die Überlassung des Themas und alle Förderung meiner Arbeit. Für fördernden Rat danke ich ferner den Herren Dr. F. Lippmann und Dr. D. Stöffler.
Der Deutschen Erdöl AG, insbesondere Herrn Prof. Dr. F. Hecht, danke ich für die Überlassung der Bohrkerne von Deiningen.
Der Deutschen Forschungsgemeinschaft danke ich für die finanzielle Unterstützung dieser Arbeit. 相似文献
43.
The line profile of H as emanating from the interior of supergranular cells was measured at sin = 0, 0.6, 0.8 and 0.9. The measurements are described and the results presented.Mitteilung aus dem Fraunhofer Institut Nr. 117. 相似文献
44.
Giulio P. Genoni Elisabeth I. Meyer Andrea Ulrich 《Aquatic Sciences - Research Across Boundaries》2003,65(2):143-157
Considering food web energetics and elemental cycling together allows the testing of hypotheses about the coevolution of biological systems and their physical environment. We investigated the energy flow and the distribution of 25 elements in the Steina River.¶We constructed an annual energy flow network and estimated the emergy ("embodied energy" that includes all the energy involved in a process) contributions of resources sustaining the system. Furthermore, we measured the concentration of various macronutrients, essential elements, and heavy metals in the physical environment and trophic compartments. Finally, we examined the hypothesis of a positive relationship between the "rarity" of an element and its tendency to bioaccumulate. To do so, we used transformity, the relative energy input required to sustain a compartment's net production or the concentration differential of an element between the living community and the physical environment.¶The resulting energy flow network is one of the most complete available for streams. In the Steina, over 99% of the energy input is transported through the system without being processed. Dissolved inorganic matter and sunlight are the largest inputs, but uptake efficiency is much higher for dissolved and particulate organic matter. Transformities of trophic compartments and elements span 6 to 7 orders of magnitude.¶The tendency to bioaccumulate was as predicted for most elements, with macronutrients showing no accumulation and heavy elements accumulating in high-transformity compartments. However, Na and K were found at highest concentrations in consumers, and Pb, Ga, and Cd in algae. Improved estimates may become possible as more knowledge is available on ecosystem flows. We suggest further ways of testing hypotheses about strategies of element processing. 相似文献
45.
Wolfgang D. Maier Sarah-Jane Barnes Julian S. Marsh 《Contributions to Mineralogy and Petrology》2003,146(1):44-61
Concentrations of the platinum-group elements have been determined in several suites of southern African flood-type basalts and mid-ocean ridge basalt (MORB), covering some 3 Ga of geologic evolution and including the Etendeka, Karoo, Soutpansberg, Machadodorp, Hekpoort, Ventersdorp and Dominion magmas. The magmas cover a compositional range from 3.7 to 18.7% MgO, 26–720 ppm Ni, 16–250 ppm Cu, and <1–255 ppb total platinum-group elements (PGE). The younger basalts (Etendeka, Karoo) tend to be depleted in PGE relative to Cu, while most of the older basalts (Hekpoort, Machadodorp, Ventersdorp, Dominion) show no PGE depletion relative to Cu. Further, the younger basalts tend to have lower average Pt/Pd ratios than the older basalts, and the MORBs have lower average Pt/Pd than the continental basalts within the broad groupings of "old" and "young" basalts. This may reflect (1) a decreasing degree of mantle melting through geologic time, and (2) source heterogeneity, in that the MORBs are derived from predominantly asthenospheric mantle, whereas the continental basalts also contain a lithospheric mantle component enriched in Pt. In addition to these factors, some PGE fractionation also occurred during differentiation of the magmas, with Pd showing incompatible behaviour and the other PGE variably compatible behaviour. The examined southern African flood-type basalts and MORB appear to offer limited prospects for magmatic sulfide ores, largely because they show little evidence for significant chalcophile metal depletion that could be the result of sulphide extraction during ascent and crystallization.Editorial responsibility: I. Parsons 相似文献
46.
Magnetic properties of soils from sites with different geological and environmental settings 总被引:7,自引:0,他引:7
Hana Fialov Günter Maier Eduard Petrovský Ale Kapi
ka Tetyana Boyko Robert Scholger MAGPROX Team 《Journal of Applied Geophysics》2006,59(4):273-283
Measurements of magnetic susceptibility of soils, reflecting magnetic enhancement of topsoils due to atmospherically deposited magnetic particles of industrial origin, are used recently in studies dealing with outlining polluted areas, as well as with approximate determination of soil contamination with heavy metals. One of the natural limitations of this method is magnetic enhancement of soils caused by weathering magnetically rich parent rock material. In this study we compare magnetic properties of soils from regions with different geological and environmental settings. Four areas in the Czech Republic and Austria were investigated, representing both magnetically rich and poor geology, as well as point-like and diffuse pollution sources. Topsoil and subsoil samples were investigated and the effect of geology and pollution was examined. Magnetic data including mass and volume magnetic susceptibility, frequency-dependent susceptibility, and main magnetic characteristics such as coercivity (Hc and Hcr) and magnetization (Ms and Mrs) parameters are compared with heavy metal contents. The aim of the paper is to assess the applicability of soil magnetometry under different geological-environmental conditions in terms of magnetic discrimination of dominant lithogenic/anthropogenic contributions to soil magnetic signature. Our results suggest that lithology represents the primary effect on soil magnetic properties. However, in case of significant atmospheric deposition of anthropogenic particles, this contribution can be clearly recognized, independent of the type of pollution source (point-like or diffuse), and discriminated from the lithogenic one. Different soil types apparently play no role. Possible effects of climate were not investigated in this study. 相似文献
47.
Forest conditions in Europe have been monitored over 20 years jointly by the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and the European Union (EU). Maps for mean bulk SO4, NO3 and NH4 deposition at around 400 intensive monitoring plots in the years 1999–2001, as well as time trends for the period 1996–2001, are presented. Mean bulk SO4 deposition at 169 plots mostly located in central Europe decreased from 7.4 to 5.8 kgS ha−1 a−1. Mean NH4 bulk deposition decreased from 6.2 to 5.3 kgN ha−1 a−1. Nitrate bulk deposition fluctuated around 5 kgN ha−1 a−1. On average, throughfall deposition was considerably higher than bulk deposition. Time trends for mean tree crown defoliation as an overall indicator for forest condition show a peak in the mid 1990s for most of the monitored main tree species and a recent increase for the years 2003 and 2004. Multivariate linear regression analyses show some significant relations between deposition and defoliation. These relations depend on the tree species and site characteristics. Effects of deposition are moderated by the influence of biotic stress factors such as insects and fungi and by abiotic stress factors, such as weather. 相似文献
48.
Modern and known-age Pleistocene fluvial sediments were investigated by optical dating of quartz to test the suitability of the approach for dating deposits from the deeply incised Middle Rhine Valley. Samples from modern flood sediments revealed skewed distributions indicating different residual levels of equivalent dose (De) within the different aliquots. Nevertheless, a substantial number of aliquots from the modern deposits reflect De values close to zero. For the Pleistocene samples, optical ages are in general consistent with age control given by the presence of the Laacher See Tephra and radiocarbon dating. However, some samples overestimate the known age by a few thousand years when using the arithmetic mean. This is apparently explained by including aliquots in the determination of mean De where the optical signal was incompletely bleached at deposition. The most difficult issue in this context is identifying a suitable approach that can distinguish between the variability of De due to partial bleaching and microdosimetry. However, even when considering these limitations it appears that optical dating will by a quite suitable method to date Pleistocene sediments from such a complex fluvial environment, especially when focusing on a precision scale beyond a few thousand years. 相似文献
49.
Robert L. Nowack Wang-Ping Chen Ulrich Kruse Saptarshi Dasgupta 《Pure and Applied Geophysics》2007,164(10):1921-1936
We carry out a sequence of numerical tests to understand conditions under which rapid changes in crustal thickness can be
reliably imaged by teleseismic body waves. Using the finite-difference method over a 2-D grid, we compute synthetic seismograms
resulting from a planar P-wavefield incident below the grid. We then image the Moho using a migration scheme based on the Gaussian beam representation
of the wavefield. The use of Gaussian beams for the downward propagation of the wavefield is particularly advantageous in
certain geologically critical cases such as overthrusting of continental lithosphere, resulting in the juxtaposition of high-velocity
mantle material over crustal rocks. In contrast to ray-based methods, Gaussian beam migration requires no special treatment
to handle such heterogeneities. Our results suggest that with adequate station spacing and signal-to-noise ratios, offsets
of the Moho, on the order of 10 km in height, can be reliably imaged beneath thickened crust at depths of about 50 km. Furthermore,
even sharp corners and edges are faithfully imaged when precise values of seismic wave speeds are available. Our tests also
demonstrate that flexibility in choices of different types of seismic phases is important, because any single phase has trade-offs
in issues such as spatial resolution, array aperture, and amplitude of signals. 相似文献
50.
Is pure groundwater safe to drink?: natural "contamination' of groundwater in Norway 总被引:1,自引:0,他引:1
David Banks Aase Kjersti Midtgrd Geir Morland Clemens Reimann Terje Strand Kjell Bjorvatn & Ulrich Siewers 《Geology Today》1998,14(3):104-113
The title of this article is designed to provoke. Naturally occurring parameters are, by definition, not contamination. Nevertheless, nature is not necessarily nice, and naturally occurring trace toxins can be every bit as undesirable as their counterparts derived from human pollution. 相似文献