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21.
Ulrich Mann 《International Journal of Earth Sciences》1989,78(1):337-348
In this paper a general concept for revealing hydrocarbon migration pathways in rock sequences is introduced. The concept uses a multidisciplinary approach based on a geochemical and a petrophysical (or mineralogical) index. These two indices provide together the migration plot which shows the direction of hydrocarbon movement.With the help of this technique, serrerai hydrocarbon migration effects were established for a sequence of continous cores from the Upper Carboniferous. The results were verified by comparing gradients of hydrocarbon concentrations relative to pore volume. In this way the relative importance of individual migration pathways were recognized, as well as presently or formerly active migration pathways.The strong influence of permeability changes on hydrocarbon movement in source beds requires the use of the »atypical pore network« model to supplement the kerogen network model. Both models help in understanding the mechanisms of primary migration, but in certain stiuations, one might be more effective than the other.
Zusammenfassung In diesem Aufsatz wird ein Konzept vorgestellt zur Erkennung von Erdölmigrationsbahnen in Gesteinsabfolgen. Das Konzept ist multidisziplinär ausgerichtet und beruht auf der Anwendung eines geochemischen und eines petrophysikalischen (oder mineralogischen) Parameters. Beide zusammen genommen erlauben die Erstellung eines Migrationsdiagramms, das angibt in welche Richtung sich die Kohlenwasserstoffe bewegen.Mittels dieser Methode wurden in einer fortlaufenden Abfolge von Bohrkernen aus dem Oberkarbon mehrere Trends für die Migrationsrichtung von Erdöl erkannt. Diese Trends wurden durch Vergleich mit Kohlenwasserstoffkonzentrationsgradienten, bezogen auf das Porenvolumen des Gesteins, verifiziert. Auf diese Art und Weise ließ sich sowohl die Bedeutung der einzelnen Migrationsbahnen relativieren als auch zwischen jetzigen und früheren Migrationswegen unterscheiden.Der starke Einfluß von Permeabilitätsänderungen auf die Bewegung von Kohlenwasserstoffen auch in Erdölmuttergesteinen fordert die Anwendung des »Atypischen Porennetzwerk-Modells« als Ergänzung zum Kerogennetzwerk-Modell. Beide Modelle tragen wesentlich zum Verständnis der Mechanismen der primären Migration von Erdöl bei, jedoch kann im Einzelfall die Verwendung des einen Modells effektiver sein als die des anderen.
Résumé L'auteur présente une méthode générale permettant de déterminer le chemin suivi par les hydrocarbures lors de leur migration à travers les roches. Cette méthode utilise une approche multidisciplinaire basée sur un indice géochimique et un indice pétrophysique (ou minéralogique). Ces deux indices combinés fournissent l'indice de migration, qui indique la direction du déplacement des hydrocarbures.Cette méthode a permis d'établir les effets de plusieurs migrations d'hydrocarbure dans une série continue de carottes du Carbonifère supérieur. Les résultats obtenus ont été vérifiés en comparant les gradients du rapport concentration d'hydrocarbure/volume des pores. On peut reconnaître, de cette manière, l'importance relative des voies individuelles de migration, ainsi que celle des voies de migration actives aujourd'hui ou dans le passé.Etant donné le rôle important joué par les différences de perméabilité dans le déplacement des hydrocarbures au sein des roches, on se réfère au modèle Atypical Pore Network, qui complète le modèle Kerogene Network. Les deux modèles sont utilisés de manière complémentaire pour comprendre les mécanismes de la migration primaire; dans des cas extrêmes, l'un d'eux peut être plus effectif que l'autre.Cette approche constitue un nouveau pas vers une meilleure identification et une meilleure quantification des effets de la migration; elle offre des avantages considérables en raison de la diversité des paramètres qui peuvent être utilisés. Comme n'importe quel autre outil d'exploration, elle ne peut être utilisée seule dans les travaux d'évaluation et d'interprétation. Pour porter tous ses fruits, elle doit être intégrée aux données géologiques, géophysiques et surtout hydrodynamiques.
. - , //. , . . .. , , ... , , « », « ». - . , , . , . , . , , , , , .相似文献
22.
Ulrich Einsle 《Aquatic Sciences - Research Across Boundaries》1988,50(2):136-165
The long-term development of crustacean associations in the Obersee of Lake Constance was studied at one central station from
1962 to 1986. In a simultaneously managed program with four additional stations from the eastern part (Bregenz Bay) to the
western überlinger See mainly the differences in horizontal distribution were focussed. It was one aim of these investigations,
to get an idea or an indication of a connexion between the recently observed eutrophication of the Obersee, and its crustacean
communities.
Due to the immigration of several species (cyclopids) or genotypes (Daphnia), the communities had changed in genetical structures, in reproduction rates and in predation or grazing impact. Dependent
on the specific annual cycles, there resulted an extermination (Heterocope, Diaphanosoma), or a long-term decrease in annual means (Mesocyclops, Cyclops abyssorum) of the “old-settled” species.
A general tendency was seen in an increase of annual averages until the middle of the seventies, and a following decrease
of population density of most of the species.
The horizontal differences in the species associations were remarkable. The Bregenz Bay showed an own aspect in its crustacean
community with high total numbers and in earlier spring development. Most of the newcomers were concentrated in the eastern
part of the lake. 相似文献
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A total of 17 alkali basalts (alkali olivine basalt, limburgite, olivine nephelinite) and quartz tholeiites, and of 10 peridotite xenoliths (or their clinopyroxenes) were analyzed for Nd and Sr isotopes. 143Nd/144Nd ratios and 87Sr/86Sr ratios of all basalts and of the majority of ultramafic xenoliths plot below the mantle array with a large variation in Nd isotopes and a smaller variation in Sr isotopes. The tholeiites were less radiogenic in Nd than the alkali basalts. Volcanics from the Eifel and Massif Central regions contain Nd and Sr, which is more radiogenic than that of the basalts from the Hessian Depression. Nd and Sr isotopic compositions of all rocks from the latter area, with the exception of one tholeiite and one peridotite plot in the same field of isotope ratios as the Ronda ultramafic tectonite (SW Spain), which ranges in composition from garnet to plagioclase peridotite. The alkali basaltic rocks are products of smaller degrees of partial melting of depleted peridotite, which has undergone a larger metasomatic alteration compared with the source rock of tholeiitic magmas. For the peridotite xenoliths such metasomatic alteration is indicated by the correlation of their K contents and isotopic compositions. We assume that the upper mantle locally can acquire isotopic signatures low in radiogenic Nd and Sr from the introduction of delaminated crust. Such granulites low in radiogenic Nd and Sr are products of early REE fractionation and granite (Rb) separation. 相似文献
25.
Wolfgang Junkermann Ulrich Platt Andreas Volz-Thomas 《Journal of Atmospheric Chemistry》1989,8(3):203-227
Photoelectric detectors for the measurement of photolysis frequencies of different trace gases in the atmosphere are described. They exhibit uniform response characteristics over one hemisphere (2 sr) and wavelength characteristics closely matched to those of the photolysis frequencies J
O1D, J
NO2, and J
NO3, respectively. Absolute calibration of the J
O1D detector was performed by chemical actinometry with an accuracy of ±16 percent. Simultaneous measurements of J
NO2 and J
O1D are presented. 相似文献
26.
Benjamin D. Santer Karl E. Taylor Tom M. L. Wigley Joyce E. Penner Philip D. Jones Ulrich Cubasch 《Climate Dynamics》1995,12(2):77-100
It has been hypothesized recently that regional-scale cooling caused by anthropogenic sulfate aerosols may be partially obscuring
a warming signal associated with changes in greenhouse gas concentrations. Here we use results from model experiments in which
sulfate and carbon dioxide have been varied individually and in combination in order to test this hypothesis. We use centered
[R (t)] and uncentered [C (t)] pattern similarity statistics to compare observed time-evolving surface temperature change patterns with the model-predicted
equilibrium signal patterns. We show that in most cases, the C (t) statistic reduces to a measure of observed global-mean temperature changes, and is of limited use in attributing observed
climate changes to a specific causal mechanism. We therefore focus on R (t), which is a more useful statistic for discriminating between forcing mechanisms with different pattern signatures but similar
rates of global mean change. Our results indicate that over the last 50 years, the summer (JJA) and fall (SON) observed patterns
of near-surface temperature change show increasing similarity to the model-simulated response to combined sulfate aerosol/CO2 forcing. At least some of this increasing spatial congruence occurs in areas where the real world has cooled. To assess the
significance of the most recent trends in R (t) and C (t), we use data from multi-century control integrations performed with two different coupled atmosphere-ocean models, which
provide information on the statistical behavior of 'unforced' trends in the pattern correlation statistics. For the combined
sulfate aerosol/CO2 experiment, the 50-year R (t) trends for the JJA and SON signals are highly significant. Results are robust in that they do not depend on the choice of
control run used to estimate natural variability noise properties. The R (t) trends for the CO2-only signal are not significant in any season. C (t) trends for signals from both the CO2-only and combined forcing experiments are highly significant in all seasons and for all trend lengths (except for trends
over the last 10 years), indicating large global-mean changes relative to the two natural variability estimates used here.
The caveats regarding the signals and natural variability noise which form the basis of this study are numerous. Nevertheless,
we have provided first evidence that both the largest-scale (global-mean) and smaller-scale (spatial anomalies about the global
mean) components of a combined CO2/anthropogenic sulfate aerosol signal are identifiable in the observed near-surface air temperature data. If the coupled-model
noise estimates used here are realistic, we can be highly confident that the anthropogenic signal that we have identified
is distinctly different from internally generated natural variability noise. The fact that we have been able to detect the
detailed spatial signature in response to combined CO2 and sulfate aerosol forcing, but not in response to CO2 forcing alone, suggests that some of the regional-scale background noise (against which we were trying to detect a CO2-only signal) is in fact part of the signal of a sulfate aerosol effect on climate. The large effect of sulfate aerosols found
in this study demonstrates the importance of their inclusion in experiments designed to simulate past and future climate change.
Received: 10 November 1994 / Accepted: 19 July 1995 相似文献
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The Sjögruvan deposit is one of the Långban-type Fe-Mn oxide deposits hosted by marble interbeds within Svecofennian metavolcanic rocks in the Bergslagen region, central Sweden. Mineralogical and geochemical studies have been carried out to clarify the premetamorphic origin of this type of deposit, which is set apart from most other Mn mineralizations by a significant enrichment in Ba, As, Sb, Pb, W and Be contained by various oxyminerals. The principal ore types at Sjögruvan are (1) hematite+quartz-magnetite, (2) hausmannite+calcite+tephroite and (3) braunite+celsian+phlogopite. The Mn ores are compositionally akin to modern Mn deposits formed by submarine hydrothermal processes (with a high Mn/Fe ratio and low contents of Co, Ni, Th, U and REE) and likely owe their existence to similar mechanisms of formation. Pb isotope data indicate that the metal source and timing of deposition is similar to the major stratabound base-metal and iron deposits in Bergslagen. All the key elements have been leached from the local felsic volcanic units and were deposited on the sea floor; the excellent Mn-Fe separation occurred in an Eh-pH gradient that essentially corresponded to the mixing zone of hydrothermal solutions and seawater. The braunite ore is chemically distinct from the hausmannite ore, with a high concentration of refractory elements (Al, Ti, Zr) and a positive Ce anomaly, which indicate a detrital/hydrogenetic contribution to its protolith. Carbon isotope ('13C) values around 0 (relative PDB) suggest that carbonates in the deposit formed directly from seawater. 相似文献