Aliphatic and aromatic hydrocarbons in coastal Caspian Sea sediments   总被引：17，自引：0，他引：17  

Tolosa I  de Mora S  Sheikholeslami MR  Villeneuve JP  Bartocci J  Cattini C 《Marine pollution bulletin》2004,48(1-2):44-60

This investigation represents the first extensive study of the spatial distribution and sources of aliphatic (n-alkanes and unresolved complex mixture of fossil hydrocarbons) and polycyclic aromatic hydrocarbons (PAHs) in coastal sediments from the Caspian Sea. PAH concentrations, n-alkanes and biomarker profiles all suggested that there was limited petrogenic contamination in the shallow North Caspian Sea sediments, which are coarse with a low total organic carbon content. In contrast, moderate to high petrogenic contamination was found in the South Caspian Sea, in particular in the offshore oil fields near Baku, Azerbaijan. Contaminant patterns indicated that the PAHs were mainly from fossil sources, with higher contributions of pyrolytic only near industrialized and urban areas. A high contribution of perylene, a geochemically derived PAH, to the total PAHs was found in the west and south at sites influenced by the Kura, Safid Rud, Terek, Sulak and Samur Rivers.  相似文献   

The Berchtesgaden magnetic anomaly     

Ulrich Bleil  Jean Pohl 《International Journal of Earth Sciences》1976,65(1):756-767

A total intensity survey of the large magnetic anomaly in the Berchtesgaden area in the Northern Calcareous Alps has been carried out. The anomaly can be simulated by two-dimensional plate-like bodies having a NS extension of about 65 km, lower boundaries between 20 and 10 km and upper boundaries up to 5 km below the surface, depending on the intensity of magnetization (1–2 · 10^–3 G). A comparison with Bouguer gravity data favours a relatively thin magnetic source layer with a lower boundary at about 10 km and an upper boundary at about 5 km. From the magnetization required for modelling it can be concluded that mafic and possibly also ultramafic rocks are the causes of the anomalies. Two interpretations are suggested: 1) The magnetic source layers could form part of the metamorphic complex of the Bohemian Massif, belonging to a paleo-European plate. There would be probably no relation to the processes involved in the formation of the Alps in this case. 2) The magnetic source layers could be part of an ancient tethyan ocean floor, and should then be considered in relation to fossil subduction zones proposed in different models for the geodynamic evolution of the Eastern Alps.

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Zusammenfassung Im Gebiet der Berchtesgadener Anomalie wurde die Totalintensität des Erdmagnetfeldes gemessen. Die Anomalie hat in NS-Richtung eine Halbwertsbreite von rund 40 km. Sie kann durch zweidimensionale, plattenförmige magnetisierte Körper mit einer NS-Erstreckung von rund 65 km, einer unteren Begrenzung zwischen rund 20 und 10 km und einer oberen Begrenzung bis 5 km unter der Oberfläche simuliert werden. Die Bouguer-Anomalie zeigt, daß eine relativ dünne magnetisierte Schicht zwischen 5 und 10 km als wahrscheinlicher anzusehen ist. Aufgrund der zur Modellrechnung erforderlichen Magnetisierung (1–2 · 10^–3 G) müssen basische, zum Teil eventuell auch ultrabasische Gesteine als Ursache der Anomalie angenommen werden. Diese Gesteine könnten einerseits Teile des sich bis weit unter die Alpen erstreckenden Kristallins der Böhmischen Masse sein. Andererseits könnten sie Reste eines ehemaligen Ozeanbodens am Südrand der europäischen Platte sein. Sie sollten dann bei den Modellen für die geodynamische Entwicklung der Alpen, die fossile Subduktionszonen postulieren, in Betracht gezogen werden.

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Résumé Un levé de l'intensité totale du champ magnétique terrestre a été exécuté dans la région de l'anomalie magnétique de Berchtesgaden, dans les Alpes calcaires du Nord. La largeur de valeur moyenne de l'anomalie est d'environ 40 km dans la direction NS. Les calculs de modèles montrent que l'anomalie est causée par un corps magnétique en forme de plaque, ayant une extension NS d'environ 65 km, la limite inférieure pouvant varier entre 20 et 10 km et la limite supérieure pouvant atteindre 5 km. Une comparaison des effets gravimétriques des modèles magnétiques avec l'anomalie de Bouguer indique que les modèles relativement minces, entre 5 et 10 km, sont plus probables. L'aimantation requise pour les calculs (1 à 2 · 10^–3 G) montre que des roches basiques et peut-être en partie ultrabasiques doivent être considérées comme causes probables de l'anomalie. Deux interprétations alternatives sont proposées: 1) Les couches magnétiques peuvent appartenir au complexe métamorphique du Massif Bohémien. 2) Il s'agit d'un ancien fragment de croûte océanique. Dans ce cas il faudrait en tenir compte dans les modèles géodynamiques expliquant la formation des Alpes Orientales par la tectonique des plaques.

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Characterization of fracture connectivity in a siliciclastic bedrock aquifer near a public supply well (Wisconsin, USA)   总被引：4，自引：2，他引：2  

Christopher A. Gellasch  Kenneth R. Bradbury  David J. Hart  Jean M. Bahr 《Hydrogeology Journal》2013,21(2):383-399

In order to protect public supply wells from a wide range of contaminants, it is imperative to understand physical flow and transport mechanisms in the aquifer system. Although flow through fractures has typically been associated with either crystalline or carbonate rocks, there is growing evidence that it can be an important component of flow in relatively permeable sandstone formations. The objective of this work is to determine the role that fractures serve in the transport of near-surface contaminants such as wastewater from leaking sewers, to public supply wells in a deep bedrock aquifer. A part of the Cambrian aquifer system in Madison, Wisconsin (USA), was studied using a combination of geophysical, geochemical, and hydraulic testing in a borehole adjacent to a public supply well. Data suggest that bedrock fractures are important transport pathways from the surface to the deep aquifer. These fractured intervals have transmissivity values several orders of magnitude higher than non-fractured intervals. With respect to rapid transport of contaminants, high transmissivity values of individual fractures make them the most likely preferential flow pathways. Results suggest that in a siliciclastic aquifer near a public supply well, fractures may have an important role in the transport of sewer-derived wastewater contaminants.  相似文献   

Accidents longitudinaux dans la Molasse rouge auct. et dans son substratum sur le versant oriental du Salève (Haute-Savoie, France)     

Bruno Mastrangelo  Jean Charollais  Roland Wernli  Jacques Metzger 《Swiss Journal of Geoscience》2013,106(2):253-263

A detailed mapping of the Salève Mountains reveals tectonically important new Molasse rouge auct. outcrops on the NW side of the Petit Salève and on the SE flank of the Grand Salève. On the SE flank the various dips indicate faults, kinks and folds that can be followed up to 5 km long and parallel to the axis of the chain and also affecting the Cretaceous substratum. This demonstrate a more complex connection of the eastern flank of the Salève Mountains with the adjacent plateau des Bornes than was previously supposed.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987113000315   总被引：2，自引：0，他引：2  

Clement Ganino  Nicholas T.Arndt  Catherine Chauvel  Alexandre Jean  Charlotte Athurion 《地学前缘(英文版)》2013,4(5):535-546

The Panzhihua gabbroic intrusion,part of the plumbing system of the Emeishan large igneous province, intruded late-Proterozoic dolomites and marls about～263 Ma ago.The dolomites in the contact aureole were converted to brucite marbles and a diverse suite of forsterite,diopside and garnet skarns.The variation in mineralogy is explained in part by differences in the composition of the protolith,particularly the proportion of silica minerals and clay,and in part by transfer of elements from intruding magmas.The trace element compositions of most marbles and skarns are very similar to those of unmetamorphosed dolomites and marls,but some contain high Si,Ti,and Fe contents that are interpreted to have come from a magmatic source.Three brucite marbles sampled～10 m from the contact of the intrusion and named "enriched brucite marble" have trace element compositions very different from their dolomitic protolith:their rare earth elements are strongly enriched whereas levels of Nb-Ta,Zr-Hf and Ti are very low.These characteristics resemble those of carbonate liquid in equilibrium with silicate liquid or more probably with silicate minerals in the case of Panzhihua,a similarity we take to indicate that the sample underwent partial melting.Samples taken up to 300 m from the contact contain brucite indicating that high temperatures persisted well into the country rocks.However,other samples collected only tens of metres from the contact are only slightly recrystallized indicating that conditions in the aureole were highly variable.We suggest that temperatures within the aureole were controlled by conduction of heat from the main intrusion and by supply of additional heat from abundant small dykes within the aureole.Circulation of fluids derived from deeper levels in the aureole flushed the carbon dioxide from the dolomite,lowering temperature needed to partially melt carbonate to the temperatures attained near the intrusion.Irregular but extensive heating destabilized the carbonates of the aureole and decarbonation reactions associated with carbonate breakdown and melting emitted a large volume of CO₂,with potential impact on global climate.  相似文献   

The effect of global warming on mortality     

Jean Calleja-Agius  Kathleen England  Neville Calleja 《Chemie der Erde / Geochemistry》2013

There is a significant relationship between ambient temperature and mortality. In healthy individuals with no underlying co-morbid conditions, there is an efficient heat regulation system which enables the body to effectively handle thermal stress. However, in vulnerable groups, especially in elderly over the age of 65 years, infants and individuals with co-morbid cardiovascular and/or respiratory conditions, there is a deficiency in thermoregulation. When temperatures exceed a certain limit, being cold winter spells or heat waves, there is an increase in the number of deaths. In particular, it has been shown that at temperatures above 27 °C, the daily mortality rate increases more rapidly per degree rise compared to when it drops below 27 °C.This is especially of relevance with the current emergency of global warming. Besides the direct effect of temperature rises on human health, global warming will have a negative impact on primary producers and livestock, leading to malnutrition, which will in turn lead to a myriad of health related issues. This is further exacerbated by environmental pollution.Public health measures that countries should follow should include not only health-related information strategies aiming to reduce the exposure to heat for vulnerable individuals and the community, but improved urban planning and reduction in energy consumption, among many others. This will reduce the carbon footprint and help avert global warming, thus reducing mortality.  相似文献   

A 70 ka record of explosive eruptions from the TALDICE ice core (Talos Dome,East Antarctic plateau)     

Biancamaria Narcisi  Jean Robert Petit  Jérôme Chappellaz 《第四纪科学杂志》2010,25(6):844-849

The new Antarctic TALDICE ice core (72° 49′ S, 159° 11′ E, 1620 m depth), containing abundant primary tephras, provides the opportunity to elucidate the late Quaternary volcanic history of the south polar region, as well as to broaden the East Antarctic tephrostratigraphic framework. Here grain size and glass compositional data for representative tephra layers from the last 70 ka core section are used for source identification. Results point to origin of layers from centres of the Melbourne Volcanic Province (McMurdo Volcanic Group), located ～250 km from the coring site. Occurrence of tephra layers within the ice core record suggests that explosive activity in the identified source was not constant over the considered period, with a minimum of activity between 20 and 35 ka, and increased activity back to 65 ka. In addition to palaeovolcanic implications, the TALDICE tephra layers offer prospects for firm correlations between diverse widely separated palaeoarchives and for accurate dating of the Antarctic climatic record. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

An imaging study of the globular cluster systems of NGC 1407 and 1400     

Duncan A. Forbes  Patricia Sánchez-Blázquez  Anna T. T. Phan  Jean P. Brodie  Jay Strader  Lee Spitler 《Monthly notices of the Royal Astronomical Society》2006,366(4):1230-1242

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Reply to Gribbin and Plagemann     

Jean Meeus 《Icarus》1975,26(2):270

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Experimental approach to generate shock veins in single crystal olivine by shear melting     

Falko Langenhorst  Jean‐Paul POIRIER  Alexander DEUTSCH  Ulrich HORNEMANN 《Meteoritics & planetary science》2002,37(11):1541-1553

Abstract— A shock experiment has been devised to produce large shear in a single crystal sample of olivine. The recovered sample exhibits macroscopic shear faults resembling shock veins in ordinary chondrites. Examination with transmission electron microscopy reveals a high density of dislocations in the bulk olivine. The shear faults appear as thin veins containing small grains of olivine and pockets of glass. The microstructure and composition of the material in the veins point to fractional crystallization of a melt. An order of magnitude calculation is consistent with the idea that the veins were produced by shear melting. These results support the view that shock veins in meteorites are the result of shear heating rather than of pressure heterogeneities.  相似文献