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Depositional model of Permian Luodianian volcanic island and its impact on the distribution of fusulinid assemblage in southern Qinghai,Northwest China

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Science China Earth Sciences 2008年第4期51卷 594-607页

作者： NIU ZhiJun XU AnWu WANG JianXiong DUAN QiFa ZHAO XiaoMing YAO HuaZhou yichang institute of geology and Mineral resources China Geological SurveyYichang 443003China

Pan-riftizational tectonic activity reached climax at Luodianian (Permian) in the East Tethyan Domain, Qinghai-Tibet Plateau. Because of eruptive volcanics and influence of terrigenous materials, a complex volcanic-sedimentary landform formed on the sea floor in southern Qinghai. Four sedimentary facies types were recognized based on detailed field mapping. Spatially, platform facies volcanic-limestone type was located at the center belt approximately trending NWW, surrounded by shallow water slope facies tuff/tuffite type at the two flanks and deep water slope facies breccia/calcirudite at the most outside. The depression facies sandstone-mudstone type, which comprised mainly mudstone, de-posited between volcanic islands (platform facies volcanic-limestone type). Based on the field map-ping and stratigraphic section data, seven rift-related sedimentary facies were recognized and a depo-sitional model for volcanic island was proposed. It is revealed that some volcanic island chain formed quickly and intermittently in the Qamdo Block during violent eruption, and small carbonate reef, shoal, platform occurred above or on edge of volcanic island, and some slope sedimentary facies surrounded volcano island chain during dormant period of volcanic activities. Three types of fusulinid assemblages were distinguished in the carbonate rocks, which deposited in varied positions of a palaeo-volcanic island: (1) Misellina-Schwagerina assemblage occurred above or on edge of volcanic island, (2) Para-fusulina assemblage was located at restricted depression facies among volcanic islands or carbonate platform, and (3) the reworked Pseudofusulina-Schwagerina assemblage occurred at slope facies near margin of volcanic island, which originally deposited in the shallow-water carbonate platform, then collapsed along the volcanic island margin with fusulinid-bearing grain-supported carbonate con-glomerate or calcirudite, and finally re-deposited on the deeper slope. The sedimentary sequen

关键词： volcanic rocks sedimentary facies depositional model fusulinid Permian Qinghai

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Hydrogen and Oxygen Isotope Fractionation Mechanism in the Hydrothermal System and Its Geologic Significance

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Acta Geologica Sinica(English Edition) 1992年第4期66卷 397-409页

作者： Chen Zhensheng Zhang Ligang yichang institute of geology and Mineral resources, Chinese Academy of Geological Sciences, yichang, Hubei Jiang Minxi yichang institute of geology and Mineral resources Chinese Academy of Geological Sciences Yichang Hubei

The geochemical behaviors of hydrogen and oxygen isotopes in the hydrothermal system and their inher-ent relationship with the water / rock exchange are discussed in this paper In addition to the temperature con-ditions, the effective W / R ratio is another factor controlling the changes in H and O isotope compositions ofthe altered rock and hydrothermal water. Besides, the application and geological significance of the water-rockexchange theory are also discussed in the light of the H and O isotope compositions and their variation charac-teristics of the mineralizing hydrothermal water and altered rocks from several mineral deposits. Finally, abrief evolutional model of H and O istotope compositions of meteoric and magmatic hydrothermal waters in ahydrothermal system is given.

关键词： hydrothermal system isotope fractionation mechanism water/rock exchnage effective W/R ratio evolutional model

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Sm-Nd,Pb-Pb and Rb-Sr Isotopic Dating and Its Dynamic Implications for the Proterozoic Augen Granite in the Yunkai Area,Western Guangdong Province

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Acta Geologica Sinica(English Edition) 2000年第2期74卷 289-296页

作者： PENG Songbai ZHANG Yeming ZHAN Mingguo CHEN Fuwen QIU Ruizhao yichang institute of geology and Mineral resources CAGSYichang 443003Hubei

The samples of ductile-rheologic deformational augen granite from the Yunkai uplift area, western Guangdong province, were determined by the whole-rock Sm-Nd, Pb-Pb and Rb-Sr isotopic dating to have an Sm-Nd isochron age of 1414±68 Ma, a Pb-Pb isochron age of 1388±90 Ma and a Rb-Sr isochron age of 490±36 Ma. The first two ages are interpreted as the formation age of this suite of granite and the last age represents the timing of the tectono-thermal event of Caledonian ductile-rheologic shear partial melting. It is indicated that in the study area not only an orogeny took place in the Caledonian, but also a more important tectono-magmatic activity occurred in the Meso-proterozoic there, which may be related to the subduction-collision between the Yangtze block and Cathaysia block.

关键词： Yunkai area Proterozoic augen granite isotopic dating ductile-rheologic shear

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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, Beijing 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

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DISCOVERY OF Chuaria-Tawuia ASSEMBLAGE IN SHILU GROUP, HAINAN ISLAND AND ITS SIGNIFICANCE

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Science China Chemistry 1990年第2期33卷 211-222页

作者：张仁杰冯少南徐光洪杨德骊鄢道平李志宏蒋大海吴炜 yichang institute of geology and Mineral resources Yichang 443003 PRC Hainan Bureau of geology and Mineral resources Hailkou 570001 PRC

The late Precambrian algal megafossils, Chuaria-Tawuia assemblage, were found for the first time in Bed 6 of the Shilu Group, Hainan Island, South China. Consequently. the geological age of the iron-ore deposits of the Shilu Group can be determined and placed into the Qingbaikou System. This meaningful discovery offers sufficient evidence for settling the protracted dispute over the ore-forming age of the Shilu iron deposits, and will be of great help for better understanding the evolutional history of geology and tectonics, as well as the further ore-prospecting of the Shilu-type iron-deposits both in the island and South China.

关键词： Chuar a-Tawuia Shilu Group Qingbaikou System.

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METALLOGENETIC MECHANISM OF LIANHUASHAN PORPHYRY TUNGSTEN DEPOSIT

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Science China Chemistry 1985年第11期28卷 1207-1217页

作者：谭运金 Ministry of geology and Mineral resources yichang institute of geology and Mineral resources

This article discusses the metallogenetic mechanism of Lianhuashan porphyry tungsten deposit on the basis of the studies of inclusion, stable isotope, mineralogy and trace *** Lianhuashan porphyry tungsten deposit originated in the hypabyssal to near surface condition. The temperature of alteration and mineralization of this deposit ranges from 150° to 650℃, indicating that the alteration and mineralization have experienced from the latemagmatic stage to the post-magmatic mesothermal *** fO, fSand pH values of metallogenetic liquid of Lianhuashan porphyry tungsten deposit are logfO=—26——42, logfS=—17——7 and pH=4.5—7.5. The ferberite mineralization was formed when logfO=—26——31, pH=4.5—5, while the scheelite and sulfides mineralization was formed when logfO=—38——42, pH=7—7.5.

关键词： METALLOGENETIC MECHANISM OF LIANHUASHAN PORPHYRY TUNGSTEN DEPOSIT OC

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Application of Pb isotopic tracing technique to constraining the source of Pb in the West Lake Longjing tea

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Chinese Journal Of Geochemistry 2011年第4期30卷 554-562页

作者： LU Yuanfa YANG Hongmei MA Liyan CHEN Xiqing WANG Qunying Department of Geochemistry Yangtze University Jingzhou 434023 China Key Laboratory of Exploration Technologies for Oil and Gas resources (Yangtze University) Ministry of Education Jingzhou 434023 China yichang institute of geology and mmeral resources Yichang 443003 China

This paper dealt with the Pb contents and Pb isotopic composition of the West Lake Longjing tea. The results showed that in the tea leaves, from young leaf →old leaf →tea limb, the Pb contents tend to increase gradu-ally from 1.63 →4.84 →6.07×10-6, wich revealed that the Pb was accumulated gradually in the tea. After cleaned, the Pb contents of tea leaves were significantly reduced. This indicated that the deposits on the surface of tea leaves made a great contributuion to Pb contents. The survey results for soils in the relevant tea gardens showed that soil from the Longjing tea garden has higher Pb contents, with an average level of 49.6×10-6, two times those of common soils (24×10-6) in China. Results of the systematic analysis for tea, tea garden soil and the samples with the relevant background of the Pb isotopic composition displayed that the Pb isotopic ratio of tea is 206Pb/207Pb=1.164±0.005 (2σ). The ratio of 206Pb/207Pb for the soil gradually decreased from residue phase, soil dilute acid extract phase, and then to urban topsoil, i.e., 1.175 →1.171 →1.170. The 208Pb/(206Pb+207Pb) ratios also show a similar variation trend. 206Pb/207Pb ratios in the samples with the relevant background were: vehicle exhaust, 1.124; coal-combustion, 1.156; atmosphere, 1.168; and water, 1.166. Comparative studies have shown that Pb pollution is popular in the environ-mental media (soil, atmosphere, water) in Hangzhou. With the aggravation of Pb pollution, the Pb isotopic composi-tion gradually changed from the natural background (soil residues) to the direction of automobile exhaust. This phe-nomenon could illustrate that the pollution source was the vehicle exhaust, while the coal-combustion contributed little to environmental pollution in Hangzhou. The Pb of the Longjing tea came mostly from soluble phase Pb in the polluted soil. Moreover, secondary pollution was caused by vehicle exhaust.

关键词：铅同位素组成西湖龙井茶同位素示踪技术茶园土壤汽车尾气应用铅同位素比值土壤残留

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DIVISION OF CARBONIFEROUS COAL-ACCUMULATING AGES, REGIONS AND ZONES IN NORTH CHINA

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Chinese Science Bulletin 1989年第13期34卷 1110-1115页

作者：张志存 yichang institute of geology and Mineral resources MGMR

During the middle-late Carboniferous, the Yumengou Group, a series of the paralic coal-bearing deposits, was formed in North China gigantic subsidence between the Yinshan and the Qinling gigantic latitudinal tectonic zones. In the Yumengou Group the coal-forming actions occurred many times, in which the coal-accumulating actions forming industrial high seams repeatedly occurred, too.

关键词： North China Carboniferous coal-accumulating age coal-accumulating region coal-accumulating zone

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Discovery of Pleuromeia-Annalepis Flora in South Chinaand Its Significance

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Chinese Science Bulletin 1994年第2期39卷 130-134页

作者：孟繁松 yichang institute of geology and Mineral resources Yichang 443003 PRC

It is well known that most of South China was in a vast expanse of ocean dur-ing Early-Aliddle Triassic, so the fossil plants are quite rare there. So far as thescope of the world is concerned, the Anisian plants are also very scarce. Inrecent years, however, a flora represented by Pleuromeia and Annalepis has beenfound in the Badong Formation in the Yangzi Gorge area, China. It occurs withMiddle Triassic marine bivalves, such as Eumorphotis (Asoella) *** (Hsu),Myophoria (Costatoria) *** mansuyi Hsu, etc., and lies over the strata withAnisian ammonites Progonoceratites. This flora, therefore, should undoubtedly be ofthe Anisian in age. This discovery will be of important significance not only for

关键词： Pleuromeia-Annalepis flora Anisian South China.

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REE Geochemistry and Petrogenesis of Some Granite Bodies Related to Tin-polymetallic Deposits in Nanling Region, South China

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Acta Geochimica 1988年第4期7卷 289-299页

作者：刘姤群杨世义 yichang institute of geology and Mineral resources Chinese Academy of Geological Sciences yichang yichang institute of geology and Mineral resources Chinese Academy of Geological Sciences yichang

Tin--polymetallic deposits, with a characteristic elemental association of ***,Zn,Au,Ag andsometimes Fe, W and Mo, are widespread in the Nanling region, South China. Like W--Sn-Nb-Ta--Be(REE)deposits, they are commonly associated with acid graniles. Therefore. it has long been considered that tin-bearing granitic magma derived from anatexis in the tin-rich belt in the sial crust is the only source of primarytin mineralization. ineluding the tin-polymetallic deposits discussed in this paper. Genetically they arp relatedto the continental crust--reworked(l--type and S--type) granites. Based on geologic and geochemical features and, particularly, REE geochemical features, it is proposedthat the granite bodies related to tin--polymetallic deposits in this region are producls of the derived acidmagma generated by partial melting and fractional crystallization from basaltic--andesititc rocks plus a smallamount of sial rocks in the lower crust.

关键词： REE Geochemistry and Petrogenesis of Some Granite Bodies Related to Tin-polymetallic Deposits in Nanling Region South China

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