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Identification of Hercynian shoshonitic intrusive rocks in central hainan Island and its geotectonic implications

Science Bulletin 2006年第20期51卷 2507-2519页

作者： XIE Caifu1, 2, ZHU Jinchu1, DING Shijiang3. ZHANG Yeming2, FU Tai’an2 & LI Zhihong2 1. State Key Laboratory for mineral Deposits Research and Department of Earth Sciences, Nanjing University, Nanjing 210093. china 2. Yichang Institute of geology and mineral resources, Yichang 443.03. china 3. hainan bureau of geology and mineral resources, haikou 570226, china Department of Otolaryngology University Hospital VU P.O. Box 7057 1007 MB Amsterdam The Netherlands State Key Laboratory for mineral Deposits Research and Department of Earth Sciences Nanjing University Nanjing 210093 China

An identification has been made of some shoshonitic intrusive rocks in central hainan Island recently. These rocks are K-rich (K2O=2.9%―5.1%, K2O/Na2O=0.95―2.12), distinctly enriched in LILE and LREE, strongly depleted in Nb, Ta, and moder- ately depleted in Sr and Ti, with (87Sr/86Sr)i = 0.70859―0.71425 and ε Nd(t) = (?2.77―?7.49). They were derived from an EMⅡ-type mantle source. The enrichment process is related to metasomatism of depleted mantle caused by a great amount of fluid-melt released from oceanic crust and terri- genous sediments at great depth (eclogite facies) during the subduction of the South china plate under the Indochina-South china Sea plate in the Carbon- iferous–Early Permian. A SHRIMP U-Pb zircon dating yields a crystallization age of 272±7 Ma for the sho- shonitic intrusions, which is coeval with the strongly peraluminous granites found in central hainan Island. These two kinds of rocks generally possess syn-intrusion ductile deformation structures. Thus they are considered to have been generated during the early stage (syn-thrust phase) of a post-collisional event. The primary magma of shoshonitic rocks was produced at a depth > 80 km by decompression- dehydration melting of previously enriched litho- spheric mantle wedge, phlogopite-bearing garnet peridotite, which was in turn caused by the break-off of a descendent slab and upwelling of a hot as- thenosphere. The rising of melts was accompaniedby crustal contamination and crystallization fractiona- tion (AFC). Combining with other related data, it is proposed that the southwards subduction and amal- gamation of the South china plate with the Indo- china-South china Sea plate took place at ca. 287- 278 Ma, which was a part of the convergence proc- ess of the Pangea supercontinent. The suture zone was probably located along the line of Song Ma-Beibu Gulf-north margin of the Yunkai Moun- tains-Wuyi Mountains.

关键词： SHRIMP U-Pb dating Hercynian shoshonitic intrusive rocks post-collisional event enriched mantle hainan Island.

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Aoyitake plagiogranite in western Tarim Block, NW china: Age, geochemistry, petrogenesis and its tectonic implications

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Science china Earth Sciences 2006年第11期49卷 1121-1134页

作者： ZHANG Chuanlin1,2, YU Haifeng3. YE Haimin2, ZHAO Yu2 & ZHANG Dongsheng4 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, china 2. Nanjing Institute of geology and mineral {3., Nanjing 210016, china 3. Tianjin Institute of geology and mineral {3., Tianjin 3.0170, china 4. The 2nd Regional Geological Investigation Party, Xinjiang bureau of geology and mineral {3., Changji 83.100, china 1. Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China 2. Nanjing Institute of geology and mineral resources Nanjing 210016 China 3. Tianjin Institute of geology and mineral resources Tianjin 300170 China 4. The 2nd Regional Geological Investigation Party Xinjiang Bureau of Geology and Mineral Resources Changji 831100 China

SHRIMPP U-Pb zircon age and geochemical and Nd isotopic data are reported for the Aoyitake plagiogranite in western Tarim Block, NW china. The plagiogranite intruded the Middle Pro- terozoic and Lower Carboniferous with an exposure area of ca. 60 km2 and crystallized at 3.0.7±4.8 Ma. Rock types mainly include tonalite, trondhjemite and minor amounts of diorite and quartz-diorite. Feldspars in the rocks are dominated by oligoclase-andesine, and minor perthite observed locally. The granites are sodic with Na/K ratios (molar) between 4 and 87. Total REE (50-220 ppm) show a clear positive correlation with SiO2. There is no LRRE/HREE fractionation (LaN/YbN=0.5-1.5), me- dium negative Eu anomalies (δ Eu=0.3.0.6), high Y content and low Sr/Y ratio (~1.0). These granites exhibit relatively juvenile Nd T2DM model ages of 470 to 580 Ma and positive εNd(3.1 Ma) values of 6.23.to 7.65. The aforementioned characteristics are similar to those of ocean island or ocean ridge plagiogranites. However, the regional geology, especially its scale, precludes that the plagiogranite pluton was derived directly from fractionational crystallization of mantle-derived basaltic magma. We interpreted that the primary magma of the pluton might be tonalitic in composition generated by ca. 50% partial melting of the juvenile basaltic crust. The primary magma experienced intensive frac- tionational crystallization, and intruded into the middle to upper crusts to form the granite pluton. In combination with the previous regional geological data, it is concluded that the plagiogranite pluton was emplaced within the Tarim Block in respond to the Carboniferous continental rifting along the Tianshan orogenic belt.

关键词： western Tarim, Aoyitake plagiogranite, age, geochemistry, tectonic implications.

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Multi-level Detachments and Petroleum Potential of the Tarim Basin

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Acta Geologica Sinica(English Edition) 1992年第4期66卷 327-338页

作者： Tang Liangjie Northwest bureau of Petroleum geology, Ministry of geology and {3. resources, Urumqi, Xinjiang Northwest bureau of Petroleum geology Ministry of Geology and Mineral Resources Urumqi Xinjiang

Four detachment systems have been found in the Tarim Basin. They are made up of the Proterozoic,Palaeozoic, Mesozoic-Eogene and Neogene-Quaternary, respectively. The shallow-level detachments are char-acterized by the occurrence of fold-thrust belts in the Meso-Cenozoic. The mid-level detachments are markedby nappes, decollement folds and drag anticlines in the Palaeozoic. The deep-level detachments are representedby ductile shear belts in the basement. Mid-and deep-level detachments mainly occur in the Northern, Centraland Southern Uplifts which are major hydrocarbon accumulation belts of large-scale oil fields. Shallow-leveldetachments mainly exist in the Kuqa, Southwestern and Southeastern Depressions, which are favourable beltsfor finding medium- and small-sized oil-gas fields.

关键词： Tarim Basin detachment layer detachment structure hydrocarbon accumulation belt

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On the siltation of the middle Yangtze River

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Science china Earth Sciences 2004年第5期47卷 463-480页

作者： YIN Hongfu1, CHEN Guojin2, LI Chang抋n1 & WEI Yuan3.1. School of Earth Sciences, china University of Geosciences, Wuhan 43.074, china 2. Hydrogeological Team, Hubei bureau of {3. and mineral resources, Jingzhou 43.100, china 3. Geological Survey of Jiangxi Province, Nanchang 3.0201, china china Univ Geosci Sch Earth Sci Wuhan 430074 Peoples R China Hubei Bur Geol & mineral resources Hydrogeol Team Jinzhou 434100 Peoples R China Geol Survey Jiangxi Province Nanchang 3300201 Peoples R China

About 5.2×108 t/a of silts from the upper reach of the Yangtze River are transported through Yichang into the middle Yangtze River. The middle Yangtze itself and its tributaries yield ca. 0.8×108 t silts annually. Of this total 6×108 t/a input of silts, ca. 1.2×108 t/a are deposited within the river artery and lakes, while ca 4.83.108 t/a are at first transported into the lower reach through Datong, and then either deposited along the river and the Yangtze Delta, or output into the sea. Along the middle Yangtze River silting generally exceeds scouring, but the spatial and temporal distributions of scour-and-fill, as well as its distribution in the river valley transections, are uneven. Along the Yichang-Chenglingji and Jiujiang-Datong Segments of the middle Yangtze, scouring exceeds or equals silting. Silting mainly occurs along the Luoshan-Wuhan-Huangshi Segments with Wuhan as the pivotal point, as well as in the Dongting and Poyang Lakes. Even in these silting-dominated areas, there are times and parts of segments that scouring prevails. As to the transections, generally the river channel of main stream is scouring-dominated, forming V-shaped sections to a depth of 203. m or more, whereas the floodplains and bar islands are silting-dominated, forming wide and relatively high flats, which are often artificially transformed into protected embankments. Because the Jingjiang Levee separates the Jianghan Plain from Yangtze to the south, little has been deposited in that plain except a few sediments from the Han River—a tributary of the middle Yangtze. This factor plus the tectonic sag of that plain has made the altitude of plain surface several meters lower than that of the levee in most of the areas. Sil-tation along the Luoshan-Wuhan-Huangshi Segments has resulted in the elevation of flood level in this and upstream segments. River channel scouring plus floodplain silting have caused the transections of the middle Yangtze valley typically with deep channel and height

关键词： the middle Yangtze, scour-and-fill, siltation, silt utilization.

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A Study on Palaeogeography and Metallogenic Conditions of Early Carboniferous Bauxite Deposits of Old Weathered Crust in Guizhou, Sichuan, Hunan and Hubei Provinces

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Acta Geologica Sinica(English Edition) 1989年第4期63卷 391-404页

作者： Liao Shifan Guizhou bureau of/geology and mineral {3., Guiyang, Guizhou Zhang Zhongmin Guizhou bureau of geology and mineral {3. Guiyang Guizhou

There are four subtypes. namely, Ia, Ib, Ic and Id of the Early Carboniferous bauxite deposits of the old weathered crust type in Guizhou, Sichuan, Hunan and Hubei provinces. They are all distributed in the Upper Yangtze old land. As a result of the Hunan-Guizhou palaeo-faulting, the crust on the northern side of the fault was uplifted and became land, thus suffering denudation. The bauxitic substances left in the weathered crust evolved and were reworked into bauxite. On the other hand, the crust on the southern side of the fault sank and remained to be part of an ocean. The bauxite deposits of Ia and Ib subtypes were formed by in-situ enrichment of residual bauxitic substances in the weathered crust of the old land, but bauxite deposits of Ic and Id subtypes resulted from transportation, accumulation and sedimentation of allothogenous bauxitic substances on the weathered crust of the old land. The processes of transportation may be distinguished as dry transportation and wet transportation, both of which proceeded under atmospheric conditions.

关键词： A Study on Palaeogeography and Metallogenic Conditions of Early Carboniferous Bauxite Deposits of Old Weathered Crust in Guizhou Sichuan

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Palaeokarst-Lateritic Origin of Bauxite in Northern Guizhou

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Acta Geologica Sinica(English Edition) 1991年第1期65卷 65-76,112页

作者： Liu Xunfeng Guizhou bureau of geology and mineral {3., Guiyang 1Wang Qingsheng Chen Youneng and Qin Dianxie also participated in the preparation of this paper.

The bauxite in northern Guizhou is shown by its unique palaeokarst forms and weathering textures andstructures to be of palaeokarst-weathering origin. On the basis of detailed studies of the sections of the bauxitedeposits, the genetic types of minerals, the hydrogen and oxygen stable isotopic composition of diaspore andcompositions of parent materials, the writer has revealed that Early Carboniferous laterization was the mainmineralizing stage of the bauxite, and the various mineralizing processes dominated by desilication andiron-separation created an excellent time-space environment for the formation of the bauxite.

关键词： Palaeokarst-Lateritic Origin of Bauxite in Northern Guizhou

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Have a correct understanding of the attribute of geologic environmentgive full play to the role of geoscience in environmental protection

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Journal of Environmental Sciences 1995年第4期7卷 491-501页

作者： Ha Chengyou(Institute of Environmental geology, Ministry of geology and mineral {3., Beijing 100081 , china)

Ｈａｖｅａｃｏｒｒｅｃｔｕｎｄｅｒｓｔａｎｄｉｎｇｏｆｔｈｅａｔｔｒｉｂｕｔｅｏｆｇｅｏｌｏｇｉｃｅｎｖｉｒｏｎｍｅｎｔｇｉｖｅｆｕｌｌｐｌａｙｔｏｔｈｅｒｏｌｅｏｆｇｅｏｓｃｉｅｎｃｅｉｎｅｎｖｉｒｏｎｍｅｎｔａｌ... 详细信息

ＨａｖｅａｃｏｒｒｅｃｔｕｎｄｅｒｓｔａｎｄｉｎｇｏｆｔｈｅａｔｔｒｉｂｕｔｅｏｆｇｅｏｌｏｇｉｃｅｎｖｉｒｏｎｍｅｎｔｇｉｖｅｆｕｌｌｐｌａｙｔｏｔｈｅｒｏｌｅｏｆｇｅｏｓｃｉｅｎｃｅｉｎｅｎｖｉｒｏｎｍｅｎｔａｌｐｒｏｔｅｃｔｉｏｎＨａＣｈｅｎｇ...

关键词： geologic environment attribute geologic resources geologic capacity geologic disaster.

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On Deep Structures of the Xikang-Yunnan Axis

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Acta Geologica Sinica(English Edition) 1989年第3期63卷 211-225页

作者： Yuan Xuecheng bureau of Exploration Geophysics and Geochemistry,Ministry of geology and mineral {3., Beijing Liu Linqun bureau of Exploration Geophysics and Geochemistry Ministry of Geology and Mineral Resources Beijing

Through recent study, the author considers that the north-south-trending Kangding-Honghe tectonic belt is not a marginal uplift zone of the Yangtze Platform but a Tethyan-type collisional tectonic belt of which the crust-upper mantle can be structurally divided into three layers. The upper layer is the brittle upper crust, dominated by overthrusting and imbrication; the middle layer is the plastic lower crust and part of the upper mantle, represented by compression and shortening; and the lower layer is the upper mantle, probably belonging to the Yangtze Platform in light of the thickness of the lithosphere.

关键词： On Deep Structures of the Xikang-Yunnan Axis

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Discovery of potassic spilite (or poenite) in Langshan Group of Tanyaokou District,Inner Mongolia,china

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Chinese Science Bulletin 1999年第6期44卷 563-567页

作者： PENG RunminDepartment of geology and mineral resources ,{3. University of Geosciences, Beijing 100083.{3. Department of geology and mineral resources China University of Geosciences Beijing China

It is believed that the albite-potash-feldspar-greenschists in the middle Proterozoic Langshan Group in Tanyaokou District are synsedimentary potassic spilite （or poenite） based on the following facts and features: （ ⅰ ） they occur in beds and look blackish （or apple） green and compact; （ ⅱ ） they bear blasto-glomeroporphyritic and blastocrystalloclastic crystals which consist of （altered） albite laths with hollow skeleton crystal texture in which there are slender dark strips and minor pyroxene, and blasto-amygdaloid filled with pyrite, chlorite, magnetite, etc.; （ ⅲ ） the results of the petrochemical diagrams show that they are orthometamorphites; （ Ⅳ ） Sm-Nd isotopic age of them is 1 824 Ma (model age (tDM) is 2 006—2 13. Ma).

关键词： potassic spilite (or poenite) middle Proterozoic Tanyaokou Deposit Inner Mongolia.

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The species diversity of fusulinaceans and high-frequency sea-level changes in the Carboniferous-Permian boundary section at Xikou, Zhen'an County,Shaanxi Province, china

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Science china Earth Sciences 2006年第7期49卷 673-683页

作者： ZHANG Haijun1, WANG Xunlian2, DING Lin1, XIA Guoying3.& WANG Lei2 1. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, china 2. Faculty of Earth Sciences and mineral resources, china University of Geosciences, Beijing 100083. china 3. Tianjin Institute of geology and mineral resources, Tianjin 3.0170, china 1. Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China 2. Faculty of Earth Sciences and mineral resources China University of Geosciences Beijing 100083 China 3. Tianjin Institute of geology and mineral resources Tianjin 300170 China

The study on the interrelation between sea-level changes and biodiversity with its evolu-tion has great significance for understanding the impact of global changes on organic evolution and exploring the inherent laws of life-environment coevolution in geological history. In this paper, the stratigraphic distribution of fusulinacean fauna in the Carboniferous-Permian boundary section at Xikou, Zhen’an County, Shaanxi Province, is analyzed quantitatively, and the relationship between the species diversity of fusulinaceans and relative sea-level changes is discussed. As a whole, the spe-cies numbers of fusulinacean fauna experience a rapid increase and an obvious decline in Xikou, Zhen’an County, from the Late Carboniferous to the Early Permian. There is a significant increase in species diversity around the Carboniferous-Permian boundary, which is one of the biggest bio-events of the fusulinacean fauna, and represents the radiation of Pseudoschwagerininae subfamily in the studied area. Integrated fusulinacean species diversity into sequence stratigraphic framework, de-tailed study suggests that the species diversity of the fusulinaceans is closely related to its relative stratigraphic location, and is essentially controlled by the sea-level changes, especially by the high-frequency sea-level changes. Generally, the species diversity of fusulinaceans is low, and the number of first and last appearance datum is small in the lower unit of high-frequency depositional cycle formed during the quick rise of the sea level; whereas the species diversity of fusulinaceans is high, and the number of first and last appearance datum is large in the upper unit of high-frequency cycle formed during the slow fall of the sea level. Within the third-order depositional sequence, the species diversity of the fusulinaceans at the first flooding surfaces and the maximum flooding surfaces is low, and it increases upward. The fusulinacean species diversity is low within the transgressive syst

关键词： fusulinaceans, species diversity, high-frequency cyclothem, sequence stratigraphy, sea-level changes, Carboniferous-Permian boundary, Zhen'an, Shaanxi.

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