检索结果-南通市图书馆

^(40)Ar-^(39)Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng,Inner Mongolia and their tectonic significance

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2002年第15期47卷 1292-1297页

作者： ZHANG Xiaohui, LI Tiesheng, PU Zhiping & WANG HuiResearch Center for Mineral Resources Exploration, Institute of geology and geophysics, chinese academy of sciences, beijing 100101, china Guangzhou Institute of Geochemistry, chinese academy of sciences, G Research Center for Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield 40Ar-39Ar plateau ages of 133 Ma (Bi) and 126 Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordil-leran nietamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.

关键词： 40Ar-39Ar age Sinistral strike-slip Louzidian-Dachengzi ductile shear zone Metamorphic core complex.

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2005年第7期48卷 1025-1039页

作者： HUANG Fei1, Kealhofer Lisa2, XIONG Shangfa3 & HUANG Fengbao1 1. Nanjing Institute of geology and Paleontology,chinese academy of sciences,Nanjing 210008,china 2. Anthropology and Sociology Department,Santa Clara University,CA 95053,USA 3. Institute of geology and geophysics,chinese academy of sciences,beijing 100029,china Nanjing Institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States Institute of geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 8720 a BP, the Aneurolepidium chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 8720 to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 4200?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 2170 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 2170 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

Occurrences of Permian radiolarians in central and eastern Nei Mongol(Inner Mongolia) and their geological significance to the Northern china Orogen

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第24期49卷 2613-2619页

作者： SHANG Qinghua Nanjing Institute of geology and Paleontology,chinese academy of sciences,Nanjing 210008,china Institute of Vertebrate Paleontology and Paleoanthropology,chinese academy of sciences,beijing 100044,china Nanjing Institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China

The Zhesi (Jisu) Formation of the Middle Per- mian in Nei Mongol (Inner Mongolia) was commonly con- sidered to be a shallow marine sequence. Here I report the radiolarians found in the argillite bed of that formation in Zhesi and Xilinhot areas. This fact indicates a deep marine sedimentary facies persisted during the Middle Permian, and suggests that the ocean between the North china Block and Siberian Craton was not closed until the Late Guadalupian. The suture of this two blocks is probably extends along the Linxi ophiolite belt, south of the Hegenshan ophiolite belt.

关键词：造山带地质意义内蒙古放射虫二叠纪

Variations of sulfur and carbon isotopes in seawater during the Doushantuo stage in late Neoproterozoic

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2003年第13期48卷 1375-1380页

作者： ZHANG Tonggang, CHU Xuelei, ZHANG Qirui, FENG Lianjun & HUO Weiguo Key Lab of Mineral Resources Exploration and Research, Institute of geology and geophysics, chinese academy of sciences, beijing 100029, china Key Lab of Mineral Resources Exploration and Research Institute of Geology and Geophysics Chinese Academy of Sciences China

Successive analyses of sulfur and carbon isotopic compositions of carbonates strata in the Doushantuo Formation in the yangtze area were accomplished through a method of extracting trace sulfate from carbonates. Sulfur and carbon isotopic compositions of coeval seawater were estimated from the samples that show the least diagenetic alteration. A high-resolution age curve of sulfur isotopes in seawater sulfates was obtained in the Doushantuo stage, which reflects the trend of variation in seawater sulfur isotopes after the Neoproterozoic snowball Earth event. Similar characteristics of variation in carbon isotopes were observed in the coeval carbonates. A large positive d 34S excursion over +20?occurs in ancient seawater sulfates in the early Doushantuo stage. Simultaneously, the d 13C values in ancient seawater carbonates exhibit a positive excursion up to 10. The maximum d 34S and d 13C values are +46.4 and +6.9? respectively. In the middle Doushantuo stage, the range of variation in d 34S values of seawater is relatively narrow, but d 13C values are quite high. Then, d 34S values of seawater become oscillating, and the same occurs in d 13C values. Negative excursions in d 34S and d 13C values occur simultaneously at the end of the Doushantuo stage, and the minimum d 34S and d 13C values dropped down to -10.1 and -5.7? respectively. The characteristics of variations in the sulfur and carbon isotopes of ancient seawater imply strong changes in oceanic environment that became beneficial to inhabitation and propagation of organism. The organic productivity and burial rate of organic carbon once reached a quite high level during the Doushantuo stage. However, the state of environment became unstable after the global glaciation. The global climate and environment possibly were fluctuating and reiterating. The negative excursions in d 34S and d 13C values occurring at the end of the Doushantuo stage may represent a global event, which might be related to oxidation of dee

关键词：硫碳同位素分馏新元古代成岩作用

Patterns of platinum-group elements in mantle peridotite, granulite xenoliths and basalt in Hannuoba

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第18期44卷 1676-1681页

作者： CHU Xuelei, LI Xiaolin, XU Jiuhua and LIU Jianming1. The Research Center of Mineral Resources Exploration , chinese academy of sciences , beijing 100101, china 2. Institute of geology , chinese academy of sciences , beijing 100029, china 3. Institute of High Energy Physics , chinese academy of sciences , beijing 100817 , china 4. beijing University of Science and Engineering , beijing 100083, china Corresponding author The Research Center of Mineral Resources Exploration Chinese Academy of Sciences Beijing China Institute of geology Chinese Academy of Sciences Beijing China Institute of High Energy Physics Chinese Academy of Sciences Beijing China beijing University of Science and Engineering Beijing China

Neutron activation analysis after preconcentration of nickel sulfide fire assay was used in measurement of Ru, Ph, Pd, Os, Ir, Pt (i.e. PGE elements) and Au concentrations for basalt, mantle and granulite xenoliths in Hannuoba. The chondrite- and primitive mantle-normalized PGE patterns generally exhibit flat (for Iherzolite), negative slope (for harzburgite),

关键词： mantle xenolith granulite xenolith basalt platinum-group element Hannuoba.

Fluid differentiation and gold mineralization

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 13-15页

作者： QIN Dajun, CAI Xinping and XU Xingwang Institute of geology, chinese academy of sciences, beijing 100029, china Institute of geology Chinese Academy of Sciences Beijing 100029 China

GOLD mineralization is closely related to ore-forming fluids. During the evolution of fluids, their naturescontinuously change, and the differentiation of the fluids dominates these changes. Fluid differentiationincludes fluid from melt, fluid immiscibility, gasseparating from fluids and so on. We can understand fluids through inclusions, stable isotope andore-forming experiments. Under the poststage reformation, the composition and phases of inclusionsmight be changed, hence, the initial forming conditions of fluids are difficult to be defined onlythrough the observation of these inclusions. Theexistence of solution phase, gas phase and solidphase (fig. 1) indicate that differentiation

关键词： fluid differentiation gold mineralization.

CENOZOIC COLLISIONAL DEFORMATION AND LITHOSPHERE TECTONIC EVOLUTION OF THE EASTERN HIMALAYAN SYNTAXIS

在线全文

学校读者我要写书评

暂无评论

地学前缘 2000年第S1期7卷 12-13页

作者： Ding Lin, Zhong Dalai, Zhang Jinjiang, Ji Jianqing(Institute of geology and geophysics, chinese academy of sciences, beijing 100029,china)

The Eastern Himalayan Syntaxis (EHS) is one of the strongest deformation area along the Himalayan belt resulted from the collision between Indian plate and the Eurasian plate since 50～60Ma, and has sensitivity tracked and preserved the whole collisional processes. It should depend on the detail geological investigations to establish the deformational accommodate mode, and the uplift history, to elucidate the deep structure and the crust\|mantle interaction of the EHS. The Namjabarwa metamorphic complex indented into the Gangdise arc along the sinistral Pai shear fault and the dextral Aniqiao shear fault on the both sides of the Great Canyon of Yalung Zangbo river since the collision of the NE corner of the Indian plate and the Eurasian Plate at 60～70Ma [1] . The distance between Yarlung Zangbo suture and Bangong—Nujiang suture is shortened more 120km in the EHS area than that of the Lhasa block.

关键词： Eastern Himalayan Syntaxis collisional deformation Magmatism and high\|pressure metamorphism Lithospheric evolution

Discovery of the budding phosphatized globular fossils from the Neoproterozoic Doushantuo Formation at Weng'an, Guizhou Province, china

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第10期16卷 1079-1083页

作者： LIU Pengju , YIN Chongyu and TANG Feng (Institute of geology, chinese academy of Geological sciences, beijing 100037, china) Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

There is much debate on biological affinities of the phosphatized globular fossils from the Neoproterozoic Doushantuo phosphorites at Weng’an, Guizhou Province. Here we report for the first time the budding structures of some of these globular fossils, which have previously been interpreted as the resting eggs and early cleavage embryos of metazoans. The budding structures are similar to the germinating tubes of the spore and zygote of living algae, suggesting that some globular fossils from the Doushantuo phosphorites bear affinity with algae. The present new information indicated various biological affinity of the phosphatized globular fossils from the Doushantuo phosphorites.

关键词： Neoproterozoic Donshantuo Formation globular fossil budding structure algae resting eggs embryos.

Modeling the climate effects of different subregional uplifts within the Himalaya-Tibetan Plateau on Asian summer monsoon evolution

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Science Bulletin 2012年第35期57卷 4617-4626页

作者： ZHANG Ran 1,JIANG DaBang 1,2,3,LIU XiaoDong 4 & TIAN ZhiPing 2,5 1 Climate Change Research Center,chinese academy of sciences,beijing 100029,china 2 Nansen-Zhu International Research Centre,Institute of Atmospheric Physics,chinese academy of sciences,beijing 100029,china 3 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia,chinese academy of sciences,beijing 100029,china 4 State Key Laboratory of Loess and Quaternary geology,Institute of Earth Environment,chinese academy of sciences,Xi’an 710075,china 5 Graduate University of chinese academy of sciences,beijing 100049,china Climate Change Research Center Chinese Academy of Sciences Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Chinese

Considering the different uplifting time of different subregions of the Himalaya-Tibetan Plateau(TP),a series of numerical simulations have been conducted with the Community Atmosphere Model(CAM4) developed at the National Center for Atmospheric Research to explore the effects of the phased tectonic uplift of the Himalaya-TP on the evolution of Asian summer *** results show that the uplifts of the Himalaya and northern TP significantly affect the evolutions of South Asian summer monsoon and northern East Asian summer monsoon *** is,the tectonic uplift of the Himalaya intensifies the South Asian summer monsoon circulation and increases the precipitation in South Asia,whereas the uplift of the northern TP intensifies the northern East Asian summer monsoon circulation and increases the precipitation in northern East *** with previous simulations,current comparative analyses of modeling results for different subregional uplifts within the Himalaya-TP help deepen our understanding of the evolutionary history of Asian monsoons.

关键词：青藏高原隆升喜马拉雅亚洲季风高原气候夏季季风次区域隆起演化建模