The effects of surface area, grain size and mineralogy on organic matter sedimentation and preservation across the modern Squamish Delta, British Columbia: the potential role of sediment surface area in the formation of petroleum source rocks   总被引：1，自引：0，他引：1  

Rupert S. Adams  R. Marc Bustin   《International Journal of Coal Geology》2001,46(2-4)

Surface sediment samples were collected from the Squamish River Delta, British Columbia, in order to determine the role of sediment surface area in the preservation of organic matter (OM) in a paralic sedimentary environment. The Squamish Delta is an actively prograding delta, located at the head of Howe Sound.Bulk total organic carbon (TOC) values across the Squamish Delta are low, ranging from 0.1 to 1.0 wt.%. The carbon/total nitrogen ratio (C_org/N) ranges from 6 to 17, which is attributed to changes in OM type and facies variations. The <25-μm fraction has TOC concentrations up to 2.0 wt.%, and a C_org/N ratio that ranges from 14 to 16. The 53–106-μm fraction has higher TOC concentrations and C_org/N ratios relative to the 25–53-μm fraction. The C_org/N ratio ranges from 9 to 18 in the 53–106-μm fraction and 5.5–10.5 in the 25–53-μm fraction. Surface area values for bulk sediments are low (0.5–3.0 m²/g) due to the large proportion of silt size material. Good correlation between surface area and TOC in bulk samples suggests that OM is adsorbed to mineral surfaces. Similar relationships between surface area and TOC were observed in size-fractionated samples. Mineralogy and elemental composition did not correlate with TOC concentration.The relationships between surface area, TOC and total nitrogen (TN) can be linked to the hydrodynamic and sedimentological conditions of the Squamish Delta. As a result, the Squamish Delta is a useful modern analogue for the formation of petroleum source rocks in ancient deltaic environments, where TOC concentrations are often significantly lower than those in source rocks formed in other geological settings.  相似文献   

Die Lagerungsverhältnisse der Altvulkanite     

Prof. Dr. Walther Klüpfel 《International Journal of Earth Sciences》1962,52(1):514-540

Zusammenfassung Es werden die Lagerungsverhältnisse der altvulkanischen Bildungen erörtert: Die fördertreue Lagerung der Tuffe und die teils kongruente, teils überschneidende, teils fördertreue Lagerung der Intrusivgruppen. Die Lagerung derselben beruht auf dem jeweiligen Verhältnis von Senkung und Hebung. Im Gegensatz dazu ist die inverse Lagerung der Scheiben innerhalb einer Intrusivgruppe bei stationärer Lage des Gebirges auf das zunehmende spezifische Gewicht der Schmelzen zurückzuführen. Diese Lagerung steht im Widerspruch zur Förderfolge. Dieser Befund bestätigt die Intrusivnatur der vorquartären Laven.Die Graben- und Kammerbasalte werden auf den Abriß eines Grabenkeils infolge der Horizontalen Dehnung und auf eine progressive Kammerbildung zurückgeführt. Sie gibt einen Hinweis auf den Raumgewinn nach unten. Es folgen Erörterungen über die Lagerungsbeziehungen der Intrusivkörper zu den Sedimenten und Tuffen. Am Schluß wird auf die methodische Anwendung der erkannten Gesetzmäßigkeiten hingewiesen. Im Anhang folgt eine Stellungnahme zu den bei der Diskussion vorgebrachten Einwänden.

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Pyroclasts are deposited in accordance with their eruption. Intrusives are found in congruent, overlapping, or in eruption-accordant positions, consequent to tectonic rise and subsidence. In stable areas the reversed succession within the volcanic complex follows an increased specific weight of the magma. Reversed successions of volcanic series corroborate the intrusive origin of the prequaternary lavas. The graben and chamber basalts depend on wedge-shaped graben subsidence, and on progressive formation of chambers.

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Résumé On examine ici les aspects des stratifications des formations volcaniques anciennes, en particulier la stratification des tuffs et celle des roches intrusives. La stratification de ces dernières est due aux diverses formes d'affaisement et de soulèvement. En contraste avec cela, la disposition inverse des plaques à l'intérieur d'un groupe de roches intrusives dans une position stationnaire de la montagne doit s'expliquer par l'accroissement du poids spécifique du magma. Cette disposition se trouve en opposition avec l'ordre d'arrivée. Cette constation permet de confirmer la nature intrusive de «laves» préquaternaires. Les basaltes des fossés et les basaltes des salles ont attribués à un graben par suite de l'extension horizontale et à une formation progressive de salles. Celle-ci apporte une indication sur le gain d'espace réalisé vers le bas.A la fin on attire l'attention sur les aspects de la stratification des corps intrusifs par rapport aux sédiments et aux tuffs ainsi que sur l'application méthodique deces résultats. Dans l'appendice suit une prise de position par rapport aux objections formulées en cours de discussion.

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Intrusiver und extrusiver Peridoditmagmatismus im alpinotypen Bereich     

Walther E. Petrascheck Jr. 《International Journal of Earth Sciences》1959,48(1):205-217

Zusammenfassung Der Widerspruch, welcher sich aus der hohen Schmelztemperatur ultrabasischer Magmen und der geringen Kontaktmetamorphose ergibt, ist allgemein weder durch den kühlen Kristallbrei noch durch die tektonische Einschuppung von Bruchstücken der Peridoditschale lösbar. Die Platznahme der Ultrabasite erfolgte teils tief intrusiv, teils seicht intrusiv im Bereich der Geosynklinalböden, teils submarin extrusiv. Sedimentogene Serpentine sind sehr selten. Das Alter der Serpentine im alpinmediteranen Raum reicht vom Altpaläozoikum bis in die oberste Kreide.  相似文献   

Considérations sur le volcanisme post-ophiolitique dans les Alpes occidentales     

Jacques Martini  Prof. Marc Vuagnat 《International Journal of Earth Sciences》1967,57(1):264-276

Résumé L'activité magmatique ophiolitique du géosynclinal alpin (diabases, gabbros, serpentines, etc.) a été suivie par une activité à caractère volcanique moins bien connue. En effet, les appareils correspondant à cette activité ont complètement disparu; nous devons nous contenter pour tous renseignements de l'étude des fragments de roches contenus dans des grauwackes tertiaires appartenant au Flysch (grès de Taveyanne, grès d'AItdorf pro parte, grès du Champsaur).La détermination de la nature originelle des laves est, en outre, rendue difficile par le fait, découvert récemment, que ces grauwackes ont subi un métamorphisme régional les plaçant dans le faciès à zéolites; on peut raisonnablement admettre qu'il s'agissait d'andésites basaltiques.L'áge des épanchements est encore indéterminé, il doit être compris entre le Crétacé supérieur et la fin de l'Eocène. L'hypothèse la plus plausible consiste à admettre que les volcans, aujourd'hui complètement érodés se trouvaient dans la partie la plus interne du domaine pennique. Toutefois au moment du dépôt des grès de Taveyanne, les coulées ne se trouvaient plus dans leur position initiale, elles avaient glissé vers l'avant-pays sous forme d'une nappe.Il est très probable que cette activité volcanique post-ophiolitique n'est pas restreinte au segment franco-suisse des Alpes occidentales mais que des formations analogues aux grès de Taveyanne se retrouvent ailleurs, notamment en Sicile et dans les Apennins.

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The magmatic activity which gave birth to the ophiolites (diabases, gabbros, serpentinites) of the alpine geosyncline was followed by subaerial volcanism. This volcanic activity is not well known as the volcanoes were completely destroyed by erosion. Our only source of information is to be found in fragments of volcanic rocks which are part of Tertiary Flysch graywackes (Taveyanne sandstones, part of the Altorf sandstones, Champsaur sandstones).The determination of the initial composition of the lavas is further complicated by metasomatic transformations; it has been recently shown that the Taveyanne graywackes were submitted to a light regional metamorphism corresponding to the zeolitic facies ofCoombs. However, it seems that these lavas were originally basaltic andesites.The age of this volcanism is not precisely known, it cannot be later than Upper Eocene as the time of deposition of the Taveyanne sandstones is Uppermost Eocene-Lower Oligocene; it is probably post-Cenomanian. It is likely that the volcanoes were located in the southern part of the Penninic zone; however at the time of deposition of the graywackes the volcanic flows had already left their initial location, gliding toward the Foreland as part of a Nappe.Very probably, remnants of this post-ophiolitic volcanism are not restricted to the French-Swiss segment of the Western Alps, but will be found elsewhere, particularly in the Apennine Mountains and in Sicily.

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Zusammenfassung Die magmatische Tätigkeit, die Ophiolithe (Diabase, Gabbros, Serpentinite) der alpinen Geosynklinale entstehen ließ, wurde von subärischem Vulkanismus abgelöst. Diese Vulkantätigkeit ist wenig bekannt, da die Vulkane durch Erosion völlig zerstört wurden. Unsere einzige Informationsquelle findet sich in vulkanischen Gesteinsfragmenten, die Bestandteile der Tertiär-Flysch-Grauwacken sind.Die Bestimmung der ursprünglichen Zusammensetzung der Laven wird weiter durch metasomatische Umwandlungen erschwert. Kürzlich wurde gezeigt, daß die Taveyanne-Grauwacken einem regionalen Metamorphismus ausgesetzt waren, welcher der zeolithischen Fazies von Coombs entspricht. Es scheint jedoch, daß diese Laven ursprünglich basaltische Andésite waren.Das Alter dieses Vulkanismus ist nicht genau bekannt; es kann aber nicht später sein als das Obere Eozän, da die Ablagerungszeit der Taveyanne-Sandsteine Oberstes Eozän—Unteres Oligozän ist. Wahrscheinlich lagen die Vulkane im südlichen Teil der penninischen Zone; zur Zeit der Ablagerung der Grauwacken waren die Vulkanite bereits in die Überschiebungsmassen mit einbezogen.Sehr wahrscheinlich sind die Überreste dieses nach-ophiolithischen Vulkanismus nicht auf den französisch-schweizerischen Abschnitt der Westalpen beschränkt, sondern werden sich auch andernorts speziell auf dem Apennin und in Sizilien finden lassen.

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The location of exploding granules     

Marc S. Allen  Steven Musman 《Solar physics》1973,32(2):311-314

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Das Verhalten von Schwermetallen beim Recycling des Fällungs- und Flockungsmittels Kalkhydrat     

H.-J. Walther  D. Kowalczyk-Cheistova 《洁净——土壤、空气、水》1980,8(3):281-284

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Absarokites from the western Mexican Volcanic Belt: constraints on mantle wedge conditions   总被引：1，自引：1，他引：0  

Marc?Hesse  Timothy?L.?GroveEmail author 《Contributions to Mineralogy and Petrology》2003,146(1):10-27

We have investigated the near liquidus phase relations of a primitive absarokite from the Mascota region in western Mexico. Sample M.102 contains ~11.6 wt% MgO, Mg#=0.73 and the lava contains Fo₉₀ olivine phenocrysts, indicating near equilibrium with the mantle. High-pressure experiments on a synthetic analogue of the absarokite composition containing low and high H₂O abundances of (~2 and ~5 wt%, respectively) were performed in a piston cylinder apparatus over the pressure range of 1.2 to 2.0 GPa. The composition containing ~2 wt% H₂O is multiply saturated with olivine and orthopyroxene at 1.6 GPa and 1,400 °C. At the same pressure, clinopyroxene appears 30 °C below the liquidus. At an H₂O content of ~5 wt% the multiple saturation with olivine and orthopyroxene occurs at 1.7 GPa and 1,300 °C. Assuming a batch-melting process, we suggest that the primitive absarokite was segregated from a depleted lherzolite or harzburgite residue at ~50 km, placing the depth of origin well within the mantle wedge beneath the Jalisco Block. A low degree (<5 %wt%) batch-melt of an original metasomatized depleted lherzolite or harzburgite source would contain the observed trace element abundances found in M.102. The liquidus phase relations are not consistent with the presence of non-peridotitic veins at the depth of last equilibration. Therefore, we propose that the Mascota absarokites segregated at an apparent melt fraction of less than 5% from a depleted peridotitic source. Melting first began at a greater depth as a small degree H₂O- and trace element- rich melt of a metasomatized peridotite that ascended into the overlying wedge and re-equilibrated with shallower, hotter mantle.Editorial responsibility: J. Hoefs  相似文献   

Near-Surface Flow Fields Deduced Using Correlation Tracking and Time-Distance Analyses     

De Rosa  Marc  Duvall  T.L.  Toomre  Juri 《Solar physics》2000,192(1-2):351-361

Near-photospheric flow fields on the Sun are deduced using two independent methods applied to the same time series of velocity images observed by SOI-MDI on SOHO. Differences in travel times between f modes entering and leaving each pixel measured using time-distance helioseismology are used to determine sites of supergranular outflows. Alternatively, correlation tracking analysis of mesogranular scales of motion applied to the same time series is used to deduce the near-surface flow field. These two approaches provide the means to assess the patterns and evolution of horizontal flows on supergranular scales even near disk center, which is not feasible with direct line-of-sight Doppler measurements. We find that the locations of the supergranular outflows seen in flow fields generated from correlation tracking coincide well with the locations of the outflows determined from the time-distance analysis, with a mean correlation coefficient after smoothing of _s=0.890. Near-surface velocity field measurements can be used to study the evolution of the supergranular network, as merging and splitting events are observed to occur in these images. The data consist of one 2048-min time series of high-resolution (0.6 pixels) line-of-sight velocity images taken by MDI on 1997 January 16–18 at a cadence of one minute.  相似文献   

Salt transport on islands in the Okavango Delta: Numerical investigations     

S. Zimmermann  P. Bauer  R. Held  W. Kinzelbach  J.H. Walther 《Advances in water resources》2006

This study uses a numerical model to investigate the groundwater flow and salt transport mechanisms below islands in the Okavango Delta. Continuous evapotranspiration on the islands results in accumulation of solutes and the formation of a saline boundary layer, which may eventually become unstable. A novel Lagrangian method is employed in this study and compared to other numerical methods. The numerical results support the geophysical observations of density fingering on Thata Island. However, the process is slow and it takes some hundreds of years until density fingering is triggered. The results are sensitive to changes of the hydraulic gradient and the evapotranspiration rate. Small changes may lead to different plume developments. Results further demonstrate that density effects may be entirely overridden by lateral flow on islands embedded in a sufficiently high regional hydraulic gradient.  相似文献   

Single GPS receiver time-relative positioning with loop misclosure corrections     

Nicolas Balard  Rock Santerre  Marc Cocard  Stéphanie Bourgon 《GPS Solutions》2006,10(1):56-62

Time-relative positioning makes use of observations taken at two different epochs and stations with a single global positioning system (GPS) receiver to determine the position of the unknown station with respect to the known station. The limitation of this method is the degradation over time of the positioning accuracy due to the temporal variation of GPS errors (ionospheric delay, satellite clock corrections, satellite ephemerides, and tropospheric delay). The impact of these errors is significantly reduced by adding to the one-way move from the known to the unknown station, a back move to the known station. A loop misclosure is computed from the coordinates obtained at the known station at the beginning and at the end of the loop, and is used to correct the coordinates of the unknown station. The field tests, presented in this paper, show that using the loop misclosure corrections, time-relative positioning accuracy can be improved by about 60% when using single frequency data, and by about 40% with dual frequency data. For a 4-min processing interval (an 8-min loop) and a 95% probability level, errors remain under 20 cm for the horizontal components and 36 cm for the vertical component with single frequency data; and under 11 cm for the horizontal components and 29 cm for the vertical component with dual frequency data.  相似文献