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Following the precedence already established during the INQUA Congress in 1932, the Middle/Upper (Late) Pleistocene boundary is defined at the base of the Last Interglacial, the Eemian Stage. It is proposed that a high-resolution core sequence from the Amsterdam Terminal (the Eemian Stage parastratotype) should constitute the Global Stratotype Section and Point (GSSP) for the base of the Upper (Late) Pleistocene Subseries (Quaternary System/Period).  相似文献   

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Although the terrane concept emerged from the study of northern hemisphere active continental margins and orogenic belts, it is largely in the Southern Hemisphere, in particular in relation to the Gondwana supercontinent, where it has seen its fullest flowering. New data continue to emerge, and new models and techniques are being actively developed. For these reasons, “Terrane Processes at the Pacific-margin of Gondwana”  相似文献   

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Along with the progress in research on the Precambrian, Molar-tooth carbonates (simplified as MT, or microsparite carbonates or MT structure) which were formed in the Middle-Late Proterozoic have become a hot subject recently. The Proterozoic Molar-tooth (MT) carbonate rocks refer to those Meso- to Neoproterozoic (1600-650 Ma) carbonates with MT structure, i.e., a series of peculiar, ptygmatically folded and spar-filled cracks in fine-grained carbonates of Precambrian age, located in the environment of mid- to inner ramp and shallow platform. MTS, like a bridge connecting the inorganic world with the organic one, are closely related to the evolution of paleo-oceans, atmosphere and biosphere. Their development and/or recession are/is related to the origin of life and the abruption of sedimentary geochemistry events of marine carbonates. By using modern instruments and testing methods adequately, the contents of oxides in sandstones were measured and the REE distribution pattern curves were established; an accurate value of isotopic ratio of 87Sr/86Sr was obtained, that is, the age of MT formation is about 750-900 Ma; C and O isotopes of some fresh micrite limestone samples were analyzed; the energy spectrum analysis revealed that the MT consists mainly of microspar calcite, while as for its chemical composition, the matrix shows outstanding peaks of Ca, Mg, Al, Si, and K. The geochemical indicators proved that Neoproterozoic MT carbonates in the Jilin-Liaoning region were developed at the margin of a stable continent, in the torrid zone where the paleo-temperature was about 50℃, the seawater had normal salinity when MT was formed during the Wanlong period in southern Jilin and during the Yingchengzi and Xingmincun periods in eastern Liaoning. The sedimentary environment was located in the inner ramp. In summary, it is of great importance to understand the origin of MT, ascertain the paleo-climate and paleo-environment characteristics, constrain the age and the stratigraphic division and comparison of the Proterozoic so as to study the geochemical characteristics of MT carbonates and their formation environment.  相似文献   

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We propose that the level at which the conodont species Idiognathodus simulator (Ellison 1941) (sensu stricto) first appears be selected to mark the base of the Gzhelian Stage, because we believe that this is the optimal level by which this boundary can be correlated. This taxon has a short range and a wide distribution, as shown by correlation of glacial-eustatic cyclothems across the Kasimovian-Gzhelian boundary interval among Midcontinent North America and the Moscow and Donets basins of eastern Europe, based on scale of the cyclothems along with several aspects of biostrati- graphy. Outside of these areas, I. simulator (sensu stricto) is known also from other parts of the U.S., and is reported from the southern Urals and south-central China in its expected position between other widespread taxa. Its first appearance is consistent with the current ammonoid placement of the boundary (first appearance of Shumardites cuyleri), and it is also compatible with certain aspects of the distribution of Eurasian fusulinid faunas (e.g., lectotype ofRauserites rossicus).  相似文献   

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The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene-Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision.  相似文献   

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In an annual cycle from March 2005 to February 2006, benthic nutrient fluxes were measured monthly in the Dongtan intertidal flat within the Changjiang (Yangtze River) Estuary. Except for NH4^+, there always showed high fluxes from overlying water into sediment for other four nutrients. Sediments in the high and middle marshes, covered with halophyte and consisting of macrofauna, demonstrated more capabilities of assimilating nutrients from overlying water than the low marsh. Sampling seasons and nutrient concentrations in the overlying water could both exert significant effects on these fluxes. Additionally, according to the model provided by previous study, denitrification rates, that utilizing NO3- transported from overlying water (Dw) in Dongtan sediments, were estimated to be from -16 to 193 μmol·h^-1·m^-2 with an average value of 63 μmol·h^-1·m^-2 (n=18). These estimated values are still underestimates of the in-situ rates owing to the lack of consideration of DN, i.e., denitrification supported by the local NO3^- production via nitrification.  相似文献   

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Mineral and organic matter either soluble or suspended are transported by the rivers and when deposited in the bed of the river or in the water reservoir, sediments are formed, whose chemical composition may serve as a fingerprint of the history of the ecosystem. The results of the studies of sediments in water systems (river catchments, reservoirs) can be used not only for the evaluation of the current state of the ecosystem but also to prevent any dangerous environmental changes. Bottom sediments can in many ways accumulate both suspended and soluble components. The process is influenced by several factors like pH, red-ox potential, oxygen content, interactions, etc. The complexity of those phenomena causes that in order to study the accumulation processes of compounds in sediments the application of various analytical techniques is required. The authors participate in two big projects on sediment studies. The AquaTerra Project is the EU funded project on understanding river-sediment-soil-groundwater interactions for support of management of river basins and catchment areas. Our group's studies are focused on mercury determination and its speciation in sediments and fish from the Ebro River in Spain. The Dobczyce Project is the national project funded by the Ministry of Education and sciences of Poland which is also a EU member country. The latter covers many aspects of accumulation and fate processes of chemical compounds in sediments of the reservoir which supplies 60% of drinking water to about one million population in the city of Krakow in Poland.  相似文献   

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The Permian foraminifer Shanita is a genus of special paleobiogeographic importance. Current data indicate that this genus occurs in peninsular Thailand, Shan States of Burma, western Yunnan and northwestern Tibet of China, south Pamir of Tajikistan, South Afghanistan, Kuh-e Gahkum area of lran, Transcaucasus, Pinarbasi area of Turkey, and the Saiq Plateau of Oman. Studies also show that several species of Hemigordius usually coexist with Shanita, and form a peculiar Shanita-Hemigordius fauna. Localities of the Shanita-Hemigordius fauna that have been found hitherto are confined on Gondwanaderived blocks, which constitute a strip starting from peninsular Thailand and extending northwestwards and westwards to Turkey. This fauna is considered as another Permian palaeontological marker of marginal Gondwana environment.  相似文献   

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(五)五台县炭窑坪 五台山东部五台县石咀乡南5里清水河东岸有一村名叫“炭窑坪”。村子周围尽是25-19亿年前的古元古代地层,与形成煤炭的地层足足差了20亿年。附近也没有石炭纪地层出露,那么这个地名又是从何而来的呢?  相似文献   

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“地球是人类的母亲和文明的摇篮”,这一比喻形象地反映了地质与人类日常生活息息相关,我们的衣食住行无不直接或间接地来源于矿产资源,是地球和地质作用,使我们的物质生活丰富多彩。  相似文献   

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(二)我国第一洞房的故事 临汾城西20公里说的北姑射山,相传是尧帝娶鹿女的地方。古书《庄子》的"逍遥游"篇记述:"藐姑射之山,有神人居焉。肌肤若冰霜,绰约若处子。不食五谷,吸风饮露;乘云气,御飞龙,而游乎四海之外。"这里提到两点:一是姑射有神,二是有女若仙。  相似文献   

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三、从地理名称查地质变迁 1.万泉无泉 运城地区的万荣县,是万泉与荣河两个县合并命名的。而“万泉无泉”的民谚,则是指万泉县没有泉水。既然如此,为何有万泉的地名?难道这仅仅是人们的一种祈盼吗(例如中阳县有一个穷山村叫“万年饱”,就是人们饿怕了,希望以后能永世不挨饿而命名)?查县志发现,万泉原来是因“城临山涧,地多涌泉”而得名的。  相似文献   

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