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Progress and review of the studies on the end-Triassic mass extinction event

Science china Earth Sciences 2005年第12期48卷 2049-2060页

作者： DENG Shenghui1,2, LU Yuanzheng1,2,3.& XU Daoyi4.1. Research Institute of Petroleum Exploration and Development, Beijing 100083. china 2. Key Laboratory of Oil and Gas Reservoir of Petrochina, Beijing 100083. china 3. china university of geosciences, Beijing 100083. china 4. Institute of Geology, china Earthquake Administration, Beijing 100029, china 1. Research Institute of Petroleum Exploration and Development 100083 Beijing China 2. Key Laboratory of Oil and Gas Reservoir of Petrochina 100083 Beijing China 3. china university of geosciences 100083 Beijing China 4. Institute of Geology China Earthquake Administration 100029 Beijing China

The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. china has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

关键词： progress, review, end-Triassic, mass extinction, mechanism, Tr-J boundary.

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The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan,Yunnan

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Science china Earth Sciences 2005年第9期48卷 1329-1336页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3. LI Jiliang1, LIU Yifeng1 & LIU Zhenkuan4.1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, china 2. Institute of Geophysics, china Seismological Bureau, Beijing 100085, china 3. Institute of Deposition Resource, Chinese Academy of {3., Beijing 10003., china 4. School of Exploration and Information, china university of {3., Beijing 100083. china 1. Institute of Geology and Geophysics Chinese Academy of Sciences 100029 Beijing China 2. Institute of Geophysics China Seismological Bureau 100085 Beijing China 3. Institute of Deposition Resource Chinese Academy of Geosciences 100037 Beijing China 4. School of Exploration and Information China University of Geosciences 100083 Beijing China

The fault belts in Sanjiang mainly include Jinshajiang-Honghe fault, Lancangjiang fault and Nujiang fault (called Sanjiang faults) in western Yunnan Province, china. By interpreting the wide-angle seismic reflection/refraction profile between Zhefang and Binchuan, which crosses Tengchong and Baoshan blocks in Dianxi (western Yunnan) tectonic zone, we recon- struct the crustal structure with seismic traveltime tomography for crustal P-wave velocity and the seismic scattering image for crustal seismic reflection structure. In this paper, we firstly present the crustal structure images of P-wave velocity and seismic reflection under the wide-angle seismic profile. These results demonstrate that, the crustal velocity structure and seismic reflec- tion structure along the profile can be divided into 3.segments, and there is an obvious difference of crustal structure among the eastern, the western and the middle segment. Generally, crustal P-wave velocities in the Baoshan segment are 0.1―0.2 km/s slower and seismic reflection am- plitudes from Moho discontinuity are stronger than the other 2 segments. In the studied area, crustal thickness is about 4. km, and shows the thickening tendency from west to east along the profile. Additionally, it can be seen that there is one strong-amplitude seismic reflection event as bright points at the depths of 8―10 km, along the segment of 80―115 km of the profile (south- ward of Tengchong); and seismic reflection wave-field from Moho discontinuity varies obviously along the lateral direction. Finally, we make some discussions on the crustal thickening pattern in the Sanjiang fault belt, structural environment of earthquake development and the contact rela- tionship between the Tengchong block, Banshan block and Luxi trough.

关键词： Sanjiang area wide-angle seismic profile crustal structure.

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Transport network and flow mechanism of shallow ore-bearing magma in Tongling ore cluster area

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Science china Earth Sciences 2006年第4期49卷 397-407页

作者： DENG Jun1,2, WANG Qingfei1,2 , HUANG Dinghua3., WAN Li4. YANG Liqiang1,2 & GAO Bangfei1,2 1. State Key Laboratory of Geological Processes and Mineral Resources, china university of geosciences, Beijing {3. china 2. Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, china university of Geo- sciences, Beijing {3. china 3. Faculty of Earth Sciences, china university of geosciences, Wuhan 4.0}074. china 4. School of Mathematics and Information Science, Guangzhou university, Guangzhou 5104.5, china 1. State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China 2. Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of Geosciences Beijing 100083 China 3. Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China 4. School of Mathematics and Information Science Guangzhou University Guangzhou 510405 China

Abundant studies revealed that shallow intrusions of the Yanshanian epoch resulted in the mass mineralization of the Tongling region. Various evidences showed there existed a concealed magma chamber at ?10 km depth in the middle part of this region during Yanshanian epoch, from which the ore-forming magma was generated and then transported to the superficial layer. Yet the transport network and flow mechanism of the shallow ore-bearing magma, the key problem associ- ated with ore-forming process, was relatively little focused on. Integrate analysis of structural me- chanics, statistical fractal and geological facts suggested that NE trending high-angle fold-related thrust faults and the tessellated basement ones served as the main pathways for the shallow magma’s transporting, moreover, the saddle void spaces among adjacent strata in the folds upon this fault system provided the place for magma’s emplacement. So the folds in the upper part and faults in the lower part of the upper crust constituted the fluid’s transport and emplacement network. During the deformation of geologic body with multi-layer structure, the layers in the upper part tended to fold when received the jacking stress from the lower part, while the lower one inclined to fault undergoing loads of the upper part. And the producing probability of this structure assemblage was highly in- creased in the condition, such as in the Tongling area, that the mechanic rigidity of the lower layers was stronger than that of the upper ones. For the pre-existence of fluid-conducting network, the top magma with high volatile in the magma chamber transported rapidly to the superficial layer in dyking pattern, located in the void spaces of folds, filled and reconstructed them. The sudden drop of pres- sure caused the fluid unmixing from the magma and mass ore-forming elements concentration. Pulse activity of the dyking may be the principal reason why magmatic bodies in the Tongling area were spatially-temporally con

关键词： Tongling, structural network, magma intrusion, fractal, dyke.

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The Thermal Structure of the Upper Mantle in Eastern china——Inferred from the Petrological Model

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Acta Geologica Sinica(English Edition) 1991年第2期65卷 195-201页

作者： Deng Jinfu and Zhao Hailing china university of geosciences, Beijing {3. china china university of geosciences Beijing 100083 China

Cenozoic basalt in eastern china contains abundant ultramafic xenoliths which are specimens of pyrolitesreleased during basaltic magma eruption. A total of 4.5 P-T data of pyroxene in the ultramafic rocks have beencollected, which present a more precise pyroxene geotherm. The average geothermal gradient in the upper man-tle represented by the pyroxene geotherm is about 3.3. / km, which is much less than that derived from theconductive thermal model (≈14. / km), implying the great significance of convective heat transfer. The calcu-lation shows that the contributions of convective and conductive heat transfers are 79% and 21%, *** perturbation in the thermal structure of the upper mantle is an important manifestation of thetectonothermal event of Cenozoic continental rifting and intense basaltic volcanism in eastern china. Based onthe pyroxene geotherm and its comparison with the current geothermal field derived from the measurements ofthe surface heat flows, it is suggested that the Moho may be a secondary thermal boundary. The currentgeothermal field and the thermal structure of the lithosphere in eastern china may mainly reflect the result ofthe tectonothermal disturbance in the Neogene-Quaternary, in other words, the lithosphere has just begun toCool.

关键词： The Thermal Structure of the Upper Mantle in Eastern china

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Electron microscopy study of the sakhaite from endogenous borate deposit in Hunan, china

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Science china Earth Sciences 2004年第3期47卷 232-238页

作者： LIU Xiangwen1,2, YANG Guangming2, ZOU Huamin3. QU Jing1 & ZHAO Wenxia4.1. Graduate School, china university of geosciences, Wuhan 4.0}074. china 2. Test Center, china university of geosciences, Wuhan 4.0}074. china 3. Physics and Technology College, Wuhan university, Wuhan 4.0}072, china 4. Test Center, Zhongshan university, Guangzhou 510275, china china Univ Geosci Grad Sch Wuhan 430074 Peoples R China china Univ Geosci Test Ctr Wuhan 430074 Peoples R China Wuhan Univ Phys & Technol Coll Wuhan 430072 Peoples R China Zhongshan Univ Test Ctr Guangzhou 510275 Peoples R China

Sakhaite specimens from an endogenous borate deposit in Hunan Province, china have been studied in detail by means of transmission electron microscopy (TEM). The selected area electron diffraction (SAED) patterns obtained with different crystal zone axes show that the crystal system is cubic, with a = 1.4.3.nm. The convergent beam electron diffraction (CBED) patterns indicate that the point group and space group of sakhaite is m3. and Fd3., respec-tively. The space group of synthetic sakhaite determined by Chichagov (1974. is F4.3.. The possible reasons why the space groups of the natural and the synthetic sakhaites are different are discussed.

关键词： sakhaite, space group, convergent beam electron diffraction (CBED).

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Identifying rock blocks based on hierarchical rock-mass structure model

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Science china Earth Sciences 2009年第10期52卷 1612-1623页

作者： XU NengXiong School of Engineering and Technology, china university of geosciences, Beijing {3. china School of Engineering and Technology China University of Geosciences Beijing 100083 China

Rock-masses are divided into many closed blocks by deterministic and stochastic discontinuities and engineering interfaces in complex rock-mass engineering. Determining the sizes, shapes, and adjacent relations of blocks is important for stability analysis of fractured rock masses. Here we propose an algorithm for identifying spatial blocks based on a hierarchical 3. Rock-mass Structure Model (RSM). First, a model is built composed of deterministic discontinuities, engineering interfaces, and the earth's surface, and the deterministic blocks surrounded by these interfaces are traced. Then, in each deter-ministic block, a network model of stochastic discontinuities is built and the stochastic blocks are traced. Building a unitary wire frame that connects all interfaces seamlessly is the key for our algorithm to identify the above two kinds of blocks. Using this algorithm, geometric models can be built for block theory, discrete element method, and discontinuous deformation analysis.

关键词： rock-mass engineering discontinuity block identification 3. Rock-mass Structure Model network model of stochastic discontinuities

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Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications

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Science china Earth Sciences 2006年第6期49卷 561-572页

作者： HOU Qingye1,2, ZHAO Zhidan1,2, ZHANG Hongfei3. ZHANG Benren3.& CHEN Yuelong2 1. State Key Laboratory of Geological Processes and Mineral Resources, china university of {4., Beijing {3. china 2. School of Earth Science and Mineral Resources, china university of {4., Beijing {3. china 3. Faculty of Earth Sciences, china university of {4., Wuhan 4.0}074. china 1. State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China 2. School of Earth Science and Mineral Resources China University of Geosciences Beijing 100083 China 3. Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China

In order to explore the disputed issue concerning the tectonic affinity ofthe ancient ocean mantle of North Qilian Mountains (NQM), geochemical and Sr, Nd, Pb isotopiccompositions of pillow basalts of the Yushigou Ophiolite (YSGO) suite from NQM have been analyzedsystematically. The pillow basalts exhibit tholeiitic characteristics, with flatchondrite-normalized REE patterns ((La/Yb)_N = 0.98—1.27). They display no Nb, Ta, Zr, Hf negativeanomalies, and show MORB features in 2Nb-Zr/4.Y and Ti/100-Zr-YX3.tectonic discrimination *** results indicate that the Yushigou ophiolite is most likely to be formed in a mid-ocean ridgeor mature back-arc basin. Their isotopic data show a relatively broad and enriched ^(87)Sr/^(86)Sr(0.70509 — 0.70700), restricted ^(14.0}Nd/^(14.)Nd (0.512955-0.512978). Pb isotopes are in the rangeof ^(206)Pb/^(204.Pb (18.054.20.562), ^(207)Pb/^(204.Pb (15.53.-15.74.0} and ^(208)Pb/^(204.Pb(3..068-3..53.). These isotopic data imply that the basalts originated from the depleted mantle(DMM), with the involvement of enriched mantle components (mainly EMII). Geochemical comparisonsbetween the basalts in YSGO and the MORB-type basalts of ophiolite suites occurring in the knownancient Tethyan tectonic domain indicate that the ancient oceanic mantle represented by YSGO suiteforming in early Paleozoic in the North Qilian Moutains is very similar to the Tethyan mantle inboth trace elements and isotopic compositions. The North Qilian Mountains should be a part of theTethyan tectonic domain in early Paleozoic. This further implies that the Tethyan tectonic domaincan be deduced to early Paleozoic in the study area, which will be helpful to discussing thetectonic affinity and evolution of the North Qilian Mountains.

关键词： geochemistry, Indian Ocean-MORB-type isotopic signatures, Tethyan tectonic domain, Yushigou ophiolite, North Qilian Mountains.

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Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2 gas field,Tarim Basin,china

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Science china Earth Sciences 2008年第4期51卷 567-578页

作者： YU BingSong1,3. DONG HailLiang2,3.& RUAN Zhuang1,3.1 State Key Laboratory of Geological Processes and Mineral Resources, china {4. of geosciences, Beijing {3. china 2 Department of Geology, Miami {4.,Oxford, OH 4.056, USA 3.Geomicrobiology Laboratory, china {4. of geosciences, Beijing, {3. china State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Department of Geology Miami University Oxford OH 45056 USA Geomicrobiology Laboratory China University of Geoscien

This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2 gas field of the Tarim Basin, Northwestern china. Sandstone samples and pore water samples are col-lected from well KL201 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3.00 to 4.00 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2SO4.type at the shallow depth (3.00-3.3. m), to the NaHCO3.type at the intermediate depth (3.3.―3.95 m),and to the CaCl2 type at the greater depth (3.28―3.3. m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2+ concen-tration, the total inorganic carbon concentration (ΣCO2), and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2] -[Ca2+]). In the Na2SO4.water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3.water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth interval and

关键词： calcite dissolution porosity thermodynamic Tarim Basin

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Origin,evolution and extinction of Cathaysia flora

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Chinese Science Bulletin 1999年第2期44卷 100-108页

作者： SUN Keqinchina university of geosciences, Beijing {3. china china university of geosciences Beijing China

Recent research results showed that the Cathaysia flora originated and developed from the global uniform Lepidodendropsis flora of the Early Carboniferous, which had already become an independent flora in the early Late Carboniferous (Namurian B to C). The center of origin of the Cathaysia flora is restricted to the North china Plate. On the basis of the successional characteristics of the Cathaysia flora in different geological ages, it may be divided into seven evolutionary stages. The evolutionary trend of the Cathaysia flora, as a whole, was characterized by the gradual increase of the typical Cathaysian elements in the sequence from the early Late Carboniferous to the early Late Permian, which began to decline during the late Late Permian. The climatic differentiation, tectonic movement,oceanic circulation, palaeogeographical environment, extraterrestrial event and plant evolution caused the mass extinction of the Cathaysia flora on a large scale by the end of the Permian.

关键词： Asia Cathaysia flora origin evolution extinction Late Carboniferous Permian.

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The equilibrium between diagenetic calcites and dolomites and its impact on reservoir quality in the sandstone reservoir of Kela 2 gas field

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Progress in Natural Science:Materials International 2007年第9期17卷 1051-1058页

作者： Gao Zhiqian1,Yu Bingsong2,3.and Lai Xingyun2,3.1.School of Energy Resources,china university of {4.,Beijing {3.china 2.State Key Laboratory of Geological Processes and Mineral Resources,china university of {4.,Beijing {3.china 3.Ministry of Education Key Laboratory of Lithosphere Structure,Deep Processes and Exploration Technique,china university of {4.,Beijing {3.china) School of Energy Resources China University of Geosciences Beijing 100083 China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Ministry of Education Key Laboratory of Lithosphere Structure Deep Processes and Exploration Technique China University of Geosciences Beijing 100083 China

Based on the equilibrium theory of chemical reactions between water and rocks,this paper establishes a thermodynamic phase relationship diagram among calcites,dolomites and water solution under the condition of diagenesis based on the thermodynamic database of related minerals and fluids and dolomite's degree of order *** has been discovered that the equilibrium between calcites and dolomites in the diagenetic environment is strongly impacted by temperature and the Ca/Mg ratios in groundwater,and that the dolomite's degree of order in the diagenetic environment is a function of crystallization temperature and time,not controlled by water ***,the authors make a further analysis of the close relationship of chemical reaction between carbonate cements and pore water in the sandstone reservoirs of Kala 2 gas field in Kuche *** can be seen that there are different impacts on sandstone reservoir quality among the equilibrium system of calcites,dolomites and pore water at different depths of reservoirs.

关键词： diagenesis equilibrium between calcites and dolomites secondary pores Kela 2 gas field

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