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Ordovician-Silurian Boundary Extinction and Its Relationship to Iridium and carbon Isotope Anomalies

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Acta Geologica Sinica(English Edition) 1990年第1期64卷 81-92页

作者： Wang Xiaofeng Chai Zhifang Yichang institute of geology and Minieral Resources, chinese academy of geological sciences, Yichang. Hubei institute of High Energy, Academia Sinica, {3. Liu Linqun Yichang institute of geology and Mineral Resources Chinese Academy of Geological Sciences Yichang Hubei China

The abundance distributions of more than 40 elements in the No. 502 Ordovician-Silurian (O/S) bounda-ry section at Fenxiang, Yichang have been studied by RNAA and INAA. The results show that in the bounda-ry bed, there is a distinctive Ir anomaly because the Ir concentration abruptly increases to 0.64 ppb.Furthermore, the Ir is positively correlated in abundance variation with some siderophile and sulphophile ele-ments. In the same bed of the O/S boundary section at Huanghuachang, Yichang, there is also a δ^(13.C excur-sion. These geochemical signs support the hypothesis that the terminal Ordovician mass extinction was proba-bly related to extraterrestrial event, and provide new evidence for defining the O/S boundary between theHirnantia-Kinnella and G. persculptus Zones.

关键词： Ordovician-Silurian Boundary Extinction and Its Relationship to Iridium and carbon Isotope Anomalies Chen Wang

A new species of Macrocnemus (Reptilia: Protorosauria) from the Middle Triassic of southwestern china and its palaeogeographical implication

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Science china Earth sciences 2007年第11期50卷 1601-1605页

作者： LI Chun1, ZHAO LiJun2 & WANG LiTing3.1 institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of {3., beijing 100044, china 2 Zhejiang Museum of Nature History, Hangzhou 3.0012, china 3.geological Survey of Guizhou Province, Guiyang 550005, china institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China Zhejiang Museum of Nature History Hangzhou China geological Survey of Guizhou Province Guiyang China

A new species of the terrestrial protorosaur Macrocnemus is briefly described and named Macrocne-mus fuyuanensis sp. nov. The specimen was found from the marine Triassic of Yunnan Province, southwestern china. It differs from the type species M. bassanii in having the following characters: (1) 17 or 18 dorsal vertebrae; (2) relatively long humerus; and (3. femur longer than tibia. M. fuyuanensis is the only record of the genus outside Monte San Giorgio area and the first definite terrestrial reptile found from the marine Triassic of china. The age of the fossil-bearing Zhuganpo Member of the Falang Formation is believed to be the Ladinian based on associated vertebrate fauna. The existence of Mac-rocnemus in the limestone suggests the presence of a terrestrial ecosystem which probably originated from the Anisian and well developed in the Ladinian in this region. The island system along the north-coast of Tethyan during the Triassic was probably an important route for the exchanges of reptiles, especially the terrestrial reptiles between the west and east.

关键词： Protorosauria,Middle Triassic,Ladinian,Yunnan,terrestrial reptile

Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, china

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Science china Earth sciences 2007年第12期50卷 1787-1795页

作者： YUAN WanMing1,BAO ZengKuan2,DONG JinQuan2,GUO ZhaoJie3.& DENG Jun1 1 State Key Laboratory of geological Processes and Mineral Resources,china University of Geosciences,{3.100083.china 2 Laboratory of Nuclear Analysis Techniques,institute of High Energy Physics,chinese academy of sciences,{3. 10003.,china 3.Department of geology,Peking University,{3. 100871,china State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing China Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of geology Peking University Beijing China

The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different,but also fall into the Hercynian *** study has achieved 9 zircon and 7 apatite fission track analysis *** zircon fission track ages range from 158 Ma to 289 Ma and the apatite ages are between 64 Ma and 140 *** mineralization accords with the regional tectonics in the copper *** consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140―3.0℃ and retention temperature of ～250℃ for zircon fission track,and metallogenetic temperature of 120―3.0℃ in this ore *** three mineralization epochs have been identified,i.e.,289―276 Ma,23.―200 Ma and 165―158 Ma,and indicate occurrence of the min-eralization in the Indosinian and Yanshan *** to apatite fission track ages,the three tectonic-mineralizing epochs are 140―13. Ma,109―97 Ma and 64 Ma,which means age at about 100℃ after the *** three epochs lasted 146 Ma,108 Ma and about 100 Ma from ～250℃ to ～100℃ and trend decrease from early to *** is shown by the fission track modeling that this district underwent three stages of geological thermal histories,stable in Cretaceous and cooling both before Cretaceous and after 20 Ma.

关键词： mineralization age, tectonic epoch, fission track, zircon, apatite, Tuwu-Yandong, Xinjiang

Kinematics and dynamics of the Mesozoic orogeny and late-orogenic extensional collapse in the Sino-Mongolian border areas

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Science china Earth sciences 2005年第7期48卷 849-862页

作者： ZHENG Yadong 1 & WANG Tao2 1. Key Laboratory of Orogenic Belts and Crustal Evolution (Peking University), Ministry of Education, beijing 100871, china 2. institute of geology,{3., beijing 10003., china Key Laboratory of Orogenic Belts and Crustal Evolution (Peking University) Ministry of Education Beijing 100871 China institute of geology Chinese Academy of Geological Sciences Beijinq 100037 China

The Sino-Mongolian border areas underwent two important tectonic events during Mesozoic time after late Paleozoic orogeny: a late Triassic to earlier Jurassic contractional event that resulted in a large-scale south-vergent thrust during the orogeny and a late Jurassic-earlier Cretaceous extensional event in a north-south direction that formed a metamorphic core complex. The kinematic and dynamic analyses show that the thrust sheet moved southwards with a kinematic vorticity number of ca. -0.10 and sub-horizontal maximum compressive stress axis that belongs to a contraction-thickening shear. The upper plate of the late-orogenic detachment relatively moved in a 165°direction. The average kinematic vorticity in its earlier stage was 0.74 that belongs to simple shear dominated shearing and related to the maximum compressive stress axes dipping at ～66°, while the later average kinematic vorticity was ～0.55°that belongs to pure shear dominated shearing with sub-vertical maximum compressive stress axes. This suggests that the thrusting led to the crust thickened and the lower plate rocks that were originally located in the upper crust depressed through a brittle-ductile transition zone into the lower crust and became warmer. The heated rocks trended to uplift since their increasing volume and decreasing density while the loading of the upper-plate rocks increased due to the structural thickening. Under the combined effect of the loading and the thermal-uplifting, the ductile shear zone in between increased in its component of vertical pure shear. Once its pure-shear component exceeded its simple-shear one the ductile shear zone became an extension-thinned shear zone. This progressive transitional process reflects internal and essential temporal and spatial relationships: the extensional factor nucleated during the crust thickening by thrusting and increase of the extensional factor finally led to late-orogenic collapse.

关键词： Mesozoic thrusting,late-orogenic collapse,kinematic vorticity number,stress state.

Underplating in the middle-lower Yangtze Valley and model of geodynamic evolution:Constraints from geophysical data

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Science china Earth sciences 2005年第7期48卷 985-999页

作者： Lü Qingtian, HOU Zengqian, YANG Zhusen & SHI Danian institute of Mineral Resources,chinese academy of {3. sciences,beijing 10003.,china institute of Mineral Resources Chinese Academy of Geoloqical Sciences Beijina 100037 China

The lower crust and Moho are the most active boundary layers in the process of continental evolution, in which marks left by tectonic and magmatic activities during the process are preserved. The evolutionary process of the continental lithosphere may be reconstructed by exploring the structures of the lower crust and Moho. According to a study of the deep seismic reflection data obtained from the middle-lower Yangtze Valley, the authors find bright layered reflections ubiquitous in the lower crust and think that the bright reflections are caused by un-derplating of basic or ultrabasic magmas, which might be related to delamination of the lithosphere. On the basis of an integrated analysis of the geophysical and geological data of the region, the authors propose a model for geodynamic evolution of the middle-lower Yangtze Valley. This model suggests that the middle-lower Yangtze Valley had undergone such geodynamic processes as collision-compression, delamination-extension and underplating-melting since the end of the Permian, finally forming the gigantic middle-lower Yangtze Valley metallogenic belt.

关键词： lower crust deep seismic reflection underplating tectonic evolution.

Outcrop Sequence Stratigraphy of Neoproterozoic in Hunjiang Area, Jilin Province

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Journal of Earth Science 1996年第1期15卷 20-28页

作者： Qiao Xiufu Gao Linzhi (institute of geology, chinese academy of geological sciences,{3.)

Three depositional sequences have been recognized in the Neoproterozoic of southern Jilin. In this paper, we focus discussion on the parasequences and their stacking patterns in Wanlong, Badaojiang and Qinggouzi formations and on their diachronism by the theory of sequence stratigraphy, event stratigraphy and chronostratigraphy. The authors advance a new comparison of the Neoproterozoic between Jilin and Liaoning provinces.

关键词： Neoproterozoic sequence stratigraphy parasequence onlap Jilin Province.

Mass Extinction——A Fundamental Indicator for Major Natural Divisions of geological History

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Acta Geologica Sinica(English Edition) 1988年第1期1卷 1-12页

作者： Xu Daoyi Zhang Qinwen Sun Yiyin institute of geology, State Seismological Bureau, beijing institute of geology,{3., beijing institute of geology, Academia Sinica, beijing institute of geology State Seismological Bureau Beijing China

In the Phanerozoic, there are three major geological boundaries: Precambrian/***/Triassic and Cretaceous/Tertiary. Studies of these boundaries in china and over the world stronglysuggest that they have the following similar features: mass extinctions of many taxa, positive anomalies ofplatinum-group metals, and abrupt changes of stable isotopes (δ13.). It is quite probable that these were theconsequences of some rare catastrophic events of extraterrestrial origin. Hence, the three above-mentionedmass extinction events may be regarded as key indicators for the division of the geological history of thePhanerozoic.

关键词： Mass Extinction A Fundamental Indicator for Major Natural Divisions of geological History

Permian Alkaline Granites in Central Inner Mongolia and Their Geodynamic Significance

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Acta Geologica Sinica(English Edition) 1995年第1期69卷 27-39页

作者： Hong Dawei, Huang Huaizeng, Lithosphere Research center, chinese academy of geological sciences, beijingXiao Yijun,{3., chinese academy of geological sciences, beijingXu Haiming,institute of Mineral Deposits, chinese academy of geological sciences, beijingand Jin M anyuanTianjin geological academy, Ministry of Metallurgical Industry, Tianjin Fei Zhenbi Lithosphere Research center Chinese Academy of Geological Sciences Beijing China

Alkaline granites (Rb-Sr ages 276-286 Ma)occurring in the Bayan Ul-East Ujimqin belt at the southern margin of the Siberian plate originated in a tensional tectonic environment about 60 Ma earlier than the Late Devonian to Early Carboniferous collision between the Siberian and Sino-Korean plates. They belong to post-orogenic A-type granites and may be used as an indicator of the end of the orogeny. At the northern margin of the Sino-Korean plate, however, only late-orogenic calc-alkaline granites occurred during the late Caboniferous-Permian, and alkaline syenites did not appear until the Late Triassic. The asymmetric magmatism at the margins of the two neighbouring plates might be controlled by the differences in size and mass of the two plates.

关键词： alkaline granite geodynamics Inner M ongolla

New Data of Daomanite and Hongshiite

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Acta Geologica Sinica(English Edition) 2001年第4期75卷 458-465页

作者： YU Zuxiang institute of geology, chinese academy of geological sciences, beijing 10003. Fei Zhenbi institute of geology Chinese Academy of Geological Sciences Beijing 100037 [?]2Yu Zuxiang Born in 193. graduated from beijing College of geology in 1953 now research professor at the institute of geology CAGS. He has long engaged in the study of platinum minerals and mineral deposits. Tel.: (010)68328449.

In 1974 the author preliminarily reported two new platinum group minerals—daomanite and hongshiite. The two minerals were accepted by the Commission on New Minerals and Minerals Names of the International Mineralogical Association in 1976 and 1982 respectively. Because of the conditions at that time, the work was preliminary, for example, there were only reflectance values of four wave bands. Recently the author again made measurements of reflectances, corrected cell parameters by the four-circle diffractometer and electron diffraction and supplemented their new occurrences and nomenclature.

关键词： daomanite hongshiite new data