Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P
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XU Zhiqin , LI Haibing , CHEN Wen , WU Cailai , YANG Jingsui , JIN Xiaochi , CHEN Fangyuan Institute of Geology , Chinese Academy of Geological Sciences , Beijing Xie Guanglian
2002, 76(2).
Abstract:There is a large ductile shear zone, 2 km wide and more than 3SO km long, in the South Qilian Mountains, western China. It is composed of volcanic, granitic and calcareous mylonites. The microstructures of the ductile shear zone show nearly E-W extending subvertical foliation, horizontal and oblique stretching lineations, shearing sense from sinis-tral to oblique sinistral strike-slip from east to west, "A" type folds and abundant granitic veins. Measured lattice preferred orientations (LPOs) of the mylonitic and recrystallized quartz of the granitic mylonite in the west segment suggest a strong LPO characterized by the dominant slip systems {1010}
DENG TaoInstitute of Vertebrate Paleontology , Paleoanthropology , Chinese Academy of Sciences , Beijing , Chinaand W. DOWNS Bilby Research Center , Northern Arizona University , Flagstaff , AZ - , USA Fei Zhenbi
2002, 76(2).
Abstract:Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for the study of the evolution of the family and its relation to climatic changes. Taxonomic diversity, new records and extinctions are estimated for each Chinese Neogene mammal faunal unit (NMU). The diversity of Chinese Rhinocerotidae varies noticeably throughout the Neogene and is recognized within five stages: the Middle Miocene and Late Miocene are stages of high diversity and the Early Miocene, early Late Miocene and Pliocene are stages of low diversity. Rhinocerotid diversity and morphology are closely related to environmental factors and particularly sensitive to changes in ambient temperature and humidity. The interpretation of climatic variation reflected in the evolution of Rhinocerotidae corresponds precisely with the conclusions drawn from other workers and provides new evidence fen-research on the Neogene terrestrial ecosystem in China.
LI Yuejun , WANG Zhaoming , WU Haoruo , HUANG Zhibin , TAN Zejinand LUO Juncheng Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing Tarim Oil Field Company , PetroChina , Korla , Xinjiang Zhu Xiling
2002, 76(2).
Abstract:The Aiketik Group, distributed at the western end of the South Tianshan Mountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. It is separated from the adjacent rocks by faults. Generally, the geologists ascribed it to the Upper Carboniferous according to Pseudostaffella sp., Profusulinella sp. and Fusulinella sp. found from the limestone and sandy limestone of Aiketik. Our radiolarian fossils were obtained from the chert samples collected from the Haladaok section located at the upper Tuoshihan River. The fossils mainly include Albaillella undulata Deflandre, Albaillella paradoxa Deflandre, Albaillella sp. aff. A. paradoxa Deflandre, Albaillella sp. cf. A. deflandrei Gourmelon, Albaillella sp., Albaillella excelsa Ishiga, Kito and Imoto (?), Belowea variabilis (Ormiston et Lane), Callella cf. C. parvispinosa Won, Entactinia cf. E. tortispina Ormiston et Lane, Entactinia aff. E. tortispina Ormiston et Lane, Entactinia variospina Won, Entactinia sp., Eostylodicty
LEE Byung-SuDepartment of Earth Science Education , Chonbuk National University , Jeonju , - , Korea Zhu Xiling
2002, 76(2).
Abstract:This paper presents a conodont biostratigraphic study on the Upper Cambrian Sesong and Hwajeol Formations in the Sabuk area, Korea. Two samples near the base of the Sesong Slate at the Pukil section contain lower Upper Cambrian conodonts, comprising Furnishina furnishi, F. kranzae, F. pernical, F. triangulate, Hertzina elongata, Laiwugnathus doidyxus?, Phakelodus elongatus, Muellerodus? obliquus, Westergaardodina matsushitai and W. moessebergensis. This is the first conodont record of the Upper Cambrian formations recovered yet in the northern limb of the Paekunsan syncline. The faunal assemblage is correctable with the lower Upper Cambrian W. matsushitai Zone of North China. Four local biozones are recognized in the Hwajeol Formation, i.e. the Proconodontus, Eoconodontus notchpeakensis, Cambrooistodus minutus and Cordylodus proavus Zones in ascending order. This zonal scheme is essentially equivalent to that of the southern limb of the Paekunsan syncline and they are correlatable with zones in other parts of the world, including North America, Australia, Iran and China.
GU Lianxing , DU Jianguo , ZHAI Jianping , ZHAO Chenghao , FAN Jianguoand ZHANG Wenlan Department of Earth Sciences , State Key Laboratory for Mineral Deposit Research , Nanjing University , Nanjing Anhui Academy of Geological Survey , Research , Hefei Department of Earth Sciences , State Key Laboratory for Mineral Deposit Research , Nanjing University , Nanjing Liu Xinzhu
2002, 76(2).
Abstract:Based upon fluid effects, retrograde metamorphism of eclogites in the Dabie region can be divided into the fluid-poor, fluid-bearing and fluid-rich stages. The fluid-poor stage is marked by polymorphic inversion, recrystallization and exsolution of solid solutions, and is thought to represent eclogite-facies retrograde environments. The fluid-bearing stage is likely to have occurred at the late stage of ecologite-facies diaphthorosis and is represented by kyanite porphyroblasts, rutile, and sodic pyroxene in association with high-pressure hydrous minerals such as phengite and zoisite (clinozoisite) without significant amount of hydrous minerals such as amphibole, epidote and biotite. The fluid-rich stage might have commenced concomitantly with lower amphibolite-facies diaphthoresis and persisted all the way towards the near-surface environment. The product of this stage is characterized by plentiful hydrous and volatile-bearing phases.The dissemination-type rutile mineralizations in eclogites might have formed by preferential shearing-induced pressure solution of gangue minerals at the fluid-bearing stage. The accompanying vein rutile was precipitated from fluids of this stage after local transport and concentration, and may hence represent proximal mobilization of titanium from the eclogite. Therefore, rutile veins can be used as an exploration indicator for dissemination-type rutile deposits.
HOU Zengqian , CHEN Wen , LU Jiren Institute of Mineral Resources , Chinese Academy of Geological Sciences Beijing , Institute of Geology , Chinese Academy of Geological Sciences , Beijing College of Earth Sciences , China University of Geosciences , Beijing Hao Ziguo Liu Xinzhu
2002, 76(2).
Abstract:Geochronology of continental flood basalts sampled from the Emei large igneous province (LIP) on the western margin of the Yangtze platform was investigated by the laser microprobe 40Ar/39Ar dating technique. These basalts yield a fairly wide range of 40Ar/39Ar ages, varying from 259 to 135 Ma. One basalt sample, at least altered, recorded the oldest 40Ar/39Ar age of about 259 Ma, corresponding to a peak eruption age of the Emei LIP continental flood basalts. Most of the samples yield much younger ages from 135 to 177 Ma, which are consistent with the K-Ar ages for the same samples (122.8-172.1 Ma). The dating data suggest that these Permian basalts had been widely affected by the regional tectonothermal event at 177-135 Ma. The event was probably caused by the convergence and collision among the Laurasia, Yangtze and Qiangtang-Qamdo continental blocks on the eastern margin of the Qinghai-Tibet plateau after the late Triassic. The age of the event reflects the timing of the peak collisional orogeny.
ZHAO Zongju , ZHU Yan , YANG Shufeng , WANG Genghai , XU Yunjun , FENG Jialiang , DENG Hongying Department of Geoscience , Zhejiang University , Hangzhou , Zhejiang Hangzhou Institute of Petroleum Geology , Hangzhou , Zhejiang Zhou Jian Fei Zhenbi
2002, 76(2).
Abstract:Through an integrated study of Mesozoic and Palaeozoic petroleum geology in southern China and a summing-up of the results of exploration, the authors tentatively put forward a set of methods of studying petroleum systems in modified residual basins or superposed basins. Its core idea is to put emphasis on the study of the dynamic evolution of petroleum systems. The tempo-spatial evolution, hydrocarbon-generating processes and hydrocarbon-generating intensities and amounts of resources in different geological stages of chief source rocks are mainly deduced backward by 3-D basin modelling. The regularities of formation and destruction of oil and gas accumulations are summarized by analyzing the fossil and existing oil and gas accumulations, the direction of migration is studied by palaeo-structural analysis, and the dynamic evolution of Palaeozoic and Mesozoic petroleum systems in southern China is studied according to stages of major tectonic movements. The authors suggest that the realistic exploration targets of Palaeozoic and Mesozoic petroleum systems in southern China are secondary and hydrocarbon-regeneration petroleum systems, while the existing primary petroleum systems are rare. They propose that the favourable areas for exploration of Palaeozoic and Mesozoic petroleum systems in southern China are the front area of the Daba Mountains and the steep anticlinal zone on the western side of the Shizhu synclinorium in northeastern Sichuan, the Funin-Yancheng-Hai'an-Xinghua-Baoying area in the northern Jiangsu basin, the Qianjiang-Xiantao-Paizhou-Chacan 1 well area in the southern part of the Chenhu area of the Jianghan basin, the South Poyang basin in Jiangxi and the North subbasin of the Chuxiong basin. This view has been supported by the discovery of the Zhujiadun gas field in the Yancheng subbasin of the northern Jiangsu basin and the Kaixiantaixi oil-bearing structure in the southern part of the Chenhu area of the Jianghan basin.
2002, 76(2).
Abstract:Based on investigation of sediments in the Yutian-Hotan Oasis at the southern margin of the Tarim basin, 14C ages and grain-size and chemical element analyses, the following views are put forward in this paper.(1) Sediments in the Yutian-Hotan Oasis are composed chiefly of "oasis soil", similar to the recent oasis soil, i.e. brown desert soil, which was formed due to pedogenesis after aeolian sand (sandy loam) and dust (loess) of 3.32-6.64 were deposited.(2) The ancient Yutian-Hotan Oasis represented by oasis soil was formed at 13000 a B.P. During the cold period of the past 13000 years, this region is characterized mainly by accumulation of sand and dust storms, and sandy oasis soil was developed in this region due to pedogenesis in an oasis environment; during the warm period, dust falls predominated along with certain current concomitants (lacustrine facies), and silty oasis soil was formed by pedogenesis. Owing to fluctuations of cold and warm climates since 13000 a B.P., sandy oasis soil was deposited alternately with silty oasis soil and lacustrine soils. Nevertheless, the Yutian-Hotan Oasis has been preserved and developing continuously towards the contemporary time.(3) At the latest, the oasis became an important site of human inhabitancy at 10000 a B.P., and since then it has been an important base for the propagation and activity of local people in the Tarim Basin.
ZHANG Zhaochong , WANG Fusheng Institute of Geology , Chinese Academy of Geological Sciences , Beijing Liu Shuchun Liu Xinzhu
2002, 76(2).
Abstract:Based on the temporal-spatial distribution and geochemical characteristics, the Emeishan basalts can be divided into two types: high-P2O-TiO2 basalt (HPT) and low-P2O5-TiO2 basalt (LPT), which differ distinctly in geochemistry: the LPTs are characterized by relatively high abundances of MgO, total FeO and P2O5 and compatible elements (Cr, Ni, Sc), and relatively low contents of moderately compatible elements (V, Y, Yb, Co), LREE and other incompatible elements compared with the HPT. On the diagrams of trace element ratios, they are plotted on an approximately linear mixing line between depleted and enriched mantle sources, suggesting that these two types of basalts resulted from interactions of varying degrees between mantle plume and lithospheric mantle containing such volatile-rich minerals as amphibole and apatite. The source region of the LPT involves a smaller proportion of lithospheric components, while that of the HTP has a larger proportion of lithospheric components. Trachyte is generated by partial melting of the basic igneous rocks at the base of the lower continental crust. Both the two types of magmas underwent certain crystal fractionation and contamination of the lower crust at high-level magma chambers and en route to the surface.
LI Jianping , WANG Jian Guangzhou Institute of Geochemistry , Chinese Academy of Sciences , Guangzhou Liu Shuchun Zhu Xiling
2002, 76(2).
Abstract:Using the secondary spinel standard, the authors have precisely measured the Fe3+/∑ Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, and estimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine-orthopyroxene-spinel oxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle in eastern China are higher in the south than in the north. Among them, the oxygen fugacity of the North China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, while that of Northeast and South China are the same as that of the global continental mantle. The variations of mantle redox state in eastern China are mainly controlled by the C-O-H fluids derived from the asthenospheric mantle. According to the mantle oxidation state, it can be concluded that the C-O-H fluids in the lithospheric mantle of eastern China consist mainly of CO2 and minor H2O, but CH4-rich fluids should come from the asthenosphere where the ox
HU Kai , YU Chensheng , MA Dongsheng , ZHAI Jianping , ZHANG WenlanDepartment of Earth Sciences , Nanjing University , State Key Laboratoryfor Mineral Deposit Research , Nanjing University , Nanjing and XIAO Zhenyu Guangdong Nonferrous Metals Geological Exploration Bureau , Guangzhou Zhang Yuxu Zhu Xiling
2002, 76(2).
Abstract:The silver contents of organic matter in the host rocks of the Songxi shale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100×10-6to 350×10-6, which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able
SHEN Xiaohua , ZHOU Lejun , LI Hongsheng , SHEN Zhongyue , YANG Shufeng Department of Earth Sciences , Zhejiang University , Hangzhou Zhang Yuxu Zhu Xiling
2002, 76(2).
Abstract:Fractal dimensions of a terrain quantitatively describe the self-organized structure of the terrain geometry. However, the local topographic variation cannot be illustrated by the conventional box-counting method. This paper proposes a successive shift box-counting method, in which the studied object is divided into small sub-objects that are composed of a series of grids according to its characteristic scaling. The terrain fractal dimensions in the grids are calculated with the successive shift box-counting method and the scattered points with values of fractal dimensions are obtained. The present research shows that the planar variation of fractal dimensions is well consistent with fault traces and geological boundaries.
2002, 76(2).
Abstract:Reef-building Mechanism in the Early-Middle Permian of the East Kunlun Mountains TIAN Shugang(Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037) and FAN Jiasong(Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029) Reef-building was controlled by the community succession, sea-level elevation and basement changes caused by tectonics. Six kinds of reef-bnilding communities have been sorted out, which possess different compositions and occupy respective ecological sets. Types and thriving of communities were distinctive and replaced one after another in the four stages of reef development. Sedimentary cyclothems are clearly discernible in the reef-facies strata, which could be divided into
Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P