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THE ALTUN—NORTH QAIDAM ECLOGITE BELT IN WESTERN china—ANOTHER HP-UHP METAMORPHIC BELT TRUNCATED BY LARGE SCALE STRIKE-SLIP FAULT IN china

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地学前缘 2000年第S1期7卷 254-255页

作者： Zhang Jianxin, Xu Zhiqin, Yang Jingsui, Li Haibing, Wu Cailai(Institute of Geology, chinese academy of geological sciences, 26 Baiwanzhuang, beijing 100037,china, E\|mail: zjx66@***)

The Altun and North Qaidam Mountains at the northern margin of Qinghai\|Tibet plateau are separated by the Altyn Tagh sinistral strike\|slip fault, which is one of the largest strike\|slip fault systems in the world and was considered as the key element in the escape tectonics model for Euraisa\|India continent\|continent ***,the eclogites within quratzifeldspathic gneisses or pelitic gneisses characterized by amphibolite\|facies paragenesis were discovered in the Altun and the North Qaidam Mountains(Fig.1). They occur as lens or boundins within the Altun Group and Dakendaban Group respectively which previously were considered as metamorphic basement of Tarim block and Qaidam block. Our studies indicate that the eclogites outcrop in both the Altun and North Qaidam Mountains show similar occurrences, associated country rocks, rock and mineral assemblages, p\|T\% estimates, geochemistryand protolith feature and ages of peak metamorphism (see table) . The garnet\|omphacite\|phengite geothermobarometer gave equilibrium condition of \%p\%=2 8～3 0GPa and t =820～850℃ for the Altun eclogite and p =2 8GPa and \%t\%=730℃ for North Qaidam eclogite respectively(Fig..2). These p\|T conditions are in the coesite stability field. Moreover, Po lycrystalline quartz pseudomorphs after coesite have been identified in the Dulan area, North Qaidam Mountains (Song et al, in review). Therefore, these features suggest that both eclogites of Altun and North Qaidam Mountains probably are a same HP\|UHP metamorphic belt formed from the same of Early Paleozoic age deep subduction and collision, and subsequently displaced by the Altyn Tagh *** case is similar to the Dabie\|Sulu HP\|UHP metamorphic zone which was truncated by the Tanlu sinistral strike\|slip fault and splitted it into two distincts, the Dabie region and Sulu region. These correlations support an about 350～400km displacement of the Altyn Tagh sinistral strike\|slip fault (Fig.1).

关键词： Altun mountains North Qaidam Mountains HP\|UHP metamorphic b elt Altyn Tagh fault

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Characteristics and Zonation of the Cenozoic Volcanic Rocks on the Qinghai-Tibet Plateau

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Continental Dynamics 1997年第1期 1-11页

作者： YANG Jingsui XU Zhiqin BAI Wenji (Institute of Geology, chinese academy of geological sciences, beijing 100037, china) ZHAO Rough (geological Survey of Qinghai Province, Xining 810001, china)

The Cenozoic volcanic rocks on the Qinghai-Tibet plateau are recognized as four zones in space and time, i.e., the North Tertiary Zone （NTZ）, the North Quaternary Zone （NQZ）, the South Zone （SZ）, and the East Zone （EZ）, based on this and previous studies. Petrological and geochemical results show that in the four zones intermediate-acid volcanic rocks are prominent, and basic-intermediate and acid are subordinate. The rocks are characterized by high contents of K2O + Na2O （about 8 wt%）, and K2O/Na2O > 1 or close to 1, and mostly belonged to shoshonite-trachyte association and some to ultra-potassic rocks, showing affinity of orogenic genesis. Sr, Nd and Ph isotopic studies suggest that the majority of volcanic rocks were originated from the lower crush and minor, basic rocks from enriched mantle. The volcanic activity started from Paleocene, much earlier than the continent-continent collision and intercontinental subduction at the Himalayan front that started most likely from Miocene. The volcanic activities were mainly constrained by deep-seated faults which cut through the lower crust and into the mantle. That the volcanic rocks are distributed in the interior of the plateau as well as at its margin also suggests that plate subduction and collision is not the merely factor for the genesis of these rocks.

关键词： Cenozoic volcanic rocks shoshonite trachyte Qinghai-Tibet plateau

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Formation Environment of the High-Pressure Metamorphic Rocks, Western Tianshan, Xinjiang, china

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Continental Dynamics 1997年第1期 12-21页

作者： GAO Jun WANG Zongxiu (Institute of Geology, chinese academy of geological sciences, beijing 100037, china) ZHANG Lifei Akebaier SHADEKE (Department of Geology, Peking University, beijing 100871, china)

The western Tianshan high-pressure metamorphic rocks occur within the greenschist facies country rocks as small discrete blocks, lenses, bands, laminae or intercalated slabs. The protoliths of blueschists and eclogites include N-MORB, E-MORB, OIB, gabbro, basic volcanidastic rock, greywacke and other rock types. Metamorphic assemblages and geochemical dais of major, trace and rare earth elements indicate that the high-pressure rocks were formed within a B-type subduction zone along the north margin of the Early Paleozoic South Tianshan Ocean between the Tarim and the Yili-Central Tianshan plates.

关键词： high-pressure metamorphic rocks B-type subduction zone western Tianshan

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Geochemical and Nd Isotopic Characteristics of Some Rocks from the Paleoarchaean Chentaigou Supracrustal, Anshan Area, NE china

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Continental Dynamics 1997年第1期 39-46页

作者： WAN Yusheng ZHANG Zongqing WU Jiashan SONG Biao LIU Dunyi (Institute of Geology, chinese academy of geological sciences (CAGS), beijing 100037, china)

The Chentaigou supracrustal of Paleoarchaean age is located in the Chentaigou-Baijiafen area, Anshan City, Liaoning Province, and composed mainly of amphibolite, quartzite and biotite-plagioclase schist, with a small amount of meta-acid volcano-sedimentary rock. They have undergone several episodes of metamorphism. Zir- con ages of the trondhjemitic veins and the leptite （Song et al., 1994） suggest that the supracrustal rocks in the area were formed around 3.35 Ga ago. Our geochemical and Sin-Nd isotopic results indicate that the trondhjemitic veins intruding the Chentaigou supracrustal may be derived from the 3.8 Ga Baijiafen trondhjemite. On the other hand, although the calculated initial εNdvalue （-2.11） of the leptite, the meta-acid volcanosedimentary rock constituting one part of the supracrustal, is similar to that of the trondhjemitic veins, their element distributions, REE patterns in particular, are quite different. This suggests that the parent rock of the leptite was formed by the melting of some ancient continental material which is distinct from the 3.8 Ga Baijiafen trondhjemite. The amphibolite shows a geochemical composition similar to young island arc tholeiite. Eight samples of the amphibolite give a Sin-Nd isochron age of 2979 ± 384 （2σ） Ma, which is considerably younger than the zircon ages of the trondhjemitic veins and leptite. These dais are interpreted as recording a late metamorphic event. The rock association and geochemical compositions further indicate that the Chentaigou supracrustal was formed upon an old continental basement, probably in a tectonic environment similar to a modern island arc system.

关键词： Chentaigou supracrustal,. Paleoarchaean Geochemisny Chronology Anshan area

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Tracing the protolith, UHP metamorphism and exhumation ages of orthogneiss from the SW Sulu terrane (eastern china): SHRIMP U-Pb dating of mineral inclusion-bearing zircons

Tracing the protolith, UHP metamorphism and exhumation ages ...

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2004年全国岩石学与地球动力学研讨会

作者： Fulai Liu~*, Zhiqin Xu, Huaimin Xue Institute of Geology, chinese academy of geological sciences, beijing 100037, china

Orthogneisses are the major country-rocks hosting eclogites in the Sulu UHP terrane, eastem china. All of the analyzed orthogneiss cores from the main drilling hole of the chinese Continental Scientific Drilling Project (CCSD-MH) have similar major and trace element compositions and a granite protolith. These rocks have relatively high LREE/HREE ratios, strong negative Eu anomalies (Eu/Eu=0.20-0.39) and negative Ba anomalies (Ba/Ba=0.25-0.64). Coesite and coesite-bearing UHP mineral assemblages are common inclusions in zircons separated from orthogneiss, paragneiss, amphibolite, and (retrograded) eclogite of the CCSD-MH. This suggests that the eclogite, together with its country-rocks, experienced in situ ultrahigh-pressure (UHP) metamorphism. Laser Raman spectroscopy and cathodoluminescence (CL) images show that zircons from the orthogneisses are zoned and that they have distinct mineral inclusions in the different zones. Most zircons retain early magmatic cores with abundant low-pressure mineral inclusions, which are mantled with metamorphic zircon containing inclusions of coesite and other UHP minerals. The outermost rims on these grains contain low-pressure mineral inclusions, such as quartz and albite. SHRIMP U-Pb dating of the zoned zircons gives three discrete and meaningful groups of ages: Proterozoic ages for the protolith, 227±2 Ma for the coesite-bearing mantles, and 209±3 Ma for the amphibolite-facies retrograde rims. The widespread occurrence of UHP mineral inclusions in zircons from the Sulu metamorphic belt dated at about 227 Ma suggests that voluminous continental crust experienced late Triassic subduction to depths of at least 120 km and perhaps more than 200 km. 18 Ma later the terrane was rapidly exhumed to mid-crustal levels, and the UHP rocks were overprinted by amphibolite-facies metamorphism. The exhumation rate deduced from the zircon age data and previously obtained metamorphic P-Tdata is estimated to be 5.6-11.0 km/Ma. Such rapid exhumation

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PTtD Path and Fluid Evolution of HighPressure Eclogites from the Dabie Mountains,Central East china

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Continental Dynamics 1999年第1期 44-52页

作者： ZHANG Zeming Institute of Geology, chinese academy of geological sciences , beijing 100037, china WEI Bize HAN Yujing YOU Zhendong china University of Geosciences, Wuhan 430001, china

In the Dabie high pressure (HP) and ultrahigh pressure (UHP) metamorphic belts, eclogites can be divided into two types, HP eclogites (or cold eclogite) and UHP eclogites. HP eclogites occur in the southern Dabie Mountains and are characterized by the presence of glaucophane. The primary mineral assemblage of the eclogites is garnet, omphacite, phengite, epidote, glaucophane, quartz, zircon and rutile. Garnet contains abundant mineral inclusions, and exhibits apparent compositional zoning with dramatic increases in MgO and decreases in MnO from core to rim. The PTtD path indicates that supracrustal rocks were metamorphosed and deformed from epidote amphibolite to eclogite facies by subduction and collision, then uplifted to the upper crust by thrust faulting in a continuous plate convergence and reworked by retrograde metamorphism of epidote amphibolite facies and by ductile deformation. The HP metamorphic rocks were uplifted to the surface, and modified by greenschist retrograde metamorphism and ductile to brittle deformation in an extensional environment. Fluid inclusions, melt inclusions and fluid bearing minerals indicate that fluid melt rock interaction was widespread in the eclogites. Partial melting occurred during the HP metamorphism, but the migration of melt was limited, and thus magma activity was very limited. Secondary fluid inclusions are abundant in the eclogites of the Dabie Mountains. They are mainly H 2O and CO 2 rich, and halite bearing multiphase fluid inclusions. Primary fluid inclusions have not been found, possibly because rapid uplift caused decrepitation of high density inclusions.

关键词： HP eclogite PTtD path fluid and melt inclusions Dabie Mountains

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GEOLOGY　AND　GEOCHEMISTRY　OF　TIN　POLYMETALLIC　DEPOSITS　IN　SOUTHEASTERN　INNER　MONGOLIA，china－AN　INTRODUCTION

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Scientia Geologica Sinica 1995年第2期 257-272页

作者： Zhang Dequan and Xu Chuan(Institute of Mineral Deposits,chinese academy of geological sciences,beijing 100037,china)(Received December 15,1994)

ＧＥＯＬＯＧＹＡＮＤＧＥＯＣＨＥＭＩＳＴＲＹＯＦＴＩＮＰＯＬＹＭＥＴＡＬＬＩＣＤＥＰＯＳＩＴＳＩＮＳＯＵＴＨＥＡＳＴＥＲＮＩＮＮＥＲＭＯＮＧＯＬＩＡ，ＣＨＩＮＡ－ＡＮＩＮＴＲＯＤＵＣＴＩＯＮ￥ＺｈａｎｇＤｅｑｕａｎａ...

ＧＥＯＬＯＧＹＡＮＤＧＥＯＣＨＥＭＩＳＴＲＹＯＦＴＩＮＰＯＬＹＭＥＴＡＬＬＩＣＤＥＰＯＳＩＴＳＩＮＳＯＵＴＨＥＡＳＴＥＲＮＩＮＮＥＲＭＯＮＧＯＬＩＡ，ＣＨＩＮＡ－ＡＮＩＮＴＲＯＤＵＣＴＩＯＮ￥ＺｈａｎｇＤｅｑｕａｎａｎｄＸｕＣｈｕａｎ（Ｉｎｓｔｉｔｕ...

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Zircon SHRIMP U-Pb dating for the Cangshuipu volcanic rocks and its implications for the lower boundary age of the Nanhua strata in South china

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Science Bulletin 2003年第16期48卷 1663-1669页

作者： WANG Jian1, LI Xianhua2, DUAN Taizhong3, LIU Dunyi4, SONG Biao4, LI Zhongxiong1 & GAO Yonghua5 1. Chengdu Institute of Geology and Mineral Resources, china Geologi-cal Survey, Chengdu 610082, china 2. Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, china 3. Colorado School of Mines, Golden, CO 80401-1887, USA (Present address: Marathon Oil Company, Houston, TX 77056-2725, USA) 4. Institute of Geology, chinese academy of geological sciences, Bei-jing 100037, china 5. Graduate School of the chinese academy of geological sciences, beijing 100037, china Correspondence should be addressed to Wang Jian (e-mail: jianwang@ ***) Chengdu Institute of Geology and Mineral Resources China Geological Survey Chengdu 610082 China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Colorado School of Mines Golden CO 80401-1887 USA Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Graduate School of the chinese academy of geological sciences Beijing 100037 China

The continental volcanic rocks and volcaniclas-tic sedimentary conglomerates of the Cangshuipu Formation occur well in Yiyang of Hunan Province, consisting of a wedge-shaped succession of Neoproterozoic strata that over-lie with high-angle unconformity the flysch turbidites of the Lengjiaxi Group in the Upper Mesoproterozoic Eonothem. SHRIMP zircon U-Pb dating gives a weighted mean age of 814 12 Ma for the dacitic volcanic agglomerates from the lowest part of the volcanic rocks in the Cangshuipu Forma-tion. This age is younger than previously reported values of 921—933 Ma for the volcanic rocks from the Cangshuipu Formation. Our new dating represents the lower boundary age of the Neoproterozoic System in the studied area. The younger age for the Cangshuipu volcanic rocks is supported by the following observations: （1） Lower Neoproterozoic strata （814—1000 Ma） are missing in the studied area; （2） the Nanhua rift system was initiated at about 820 Ma; and （3） an age of820 Ma may be taken as the lower boundary tim-ing of the Nanhua System （even Neoproterozoic） in South china.

关键词： Zicon U-Pb dating Neoproterozoic volcanics rift basin Nanhua System.

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An　Intermediate－Fast　Spreading　Rate　of　the　Troodos　Type　Oceanic　Crust：　A　Comparison　to　Modern　Oceanic　Crusts

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Continental Dynamics 1996年第1期 70-80页

作者： Yang Jingsui and James M. Hall (Institute of Geology chinese academy of geological sciences, beijing 100037, china) (Department of Earth sciences, Dalhousie University Halifax, Nova Scotia, Canada)

ＡｎＩｎｔｅｒｍｅｄｉａｔｅ－ＦａｓｔＳｐｒｅａｄｉｎｇＲａｔｅｏｆｔｈｅＴｒｏｏｄｏｓＴｙｐｅＯｃｅａｎｉｃＣｒｕｓｔ：ＡＣｏｍｐａｒｉｓｏｎｔｏＭｏｄｅｒｎＯｃｅａｎｉｃＣｒｕｓｔｓ￥ＹａｎｇＪｉｎｇｓｕｉａｎｄ... 详细信息

ＡｎＩｎｔｅｒｍｅｄｉａｔｅ－ＦａｓｔＳｐｒｅａｄｉｎｇＲａｔｅｏｆｔｈｅＴｒｏｏｄｏｓＴｙｐｅＯｃｅａｎｉｃＣｒｕｓｔ：ＡＣｏｍｐａｒｉｓｏｎｔｏＭｏｄｅｒｎＯｃｅａｎｉｃＣｒｕｓｔｓ￥ＹａｎｇＪｉｎｇｓｕｉａｎｄＪａｍｅｓＭ．Ｈａｌｌ（Ｉｎｓｔｉ...

关键词： Rate the Troodos Spreading An Comparison

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Identification of Sources of Potential Fields with Directional Wavelet Transform:Application to Mineral Exploration

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地学前缘 2009年第S1期16卷 146-146页

作者： Dianhua Cao,Anjian Wang Institute of Mineral Resources,chinese academy of geological sciences,beijing 100037,china.

For the sustainable supply of mineral resources, blind deposits are becoming the emphasis of exploration after long-period exploitation of exposed *** collection and analysis of gravity or magnetic data represents one of the cheapest forms of large-scale geophysical *** the identification of potential fields,we can get the map of worms or skeletonizations showing the three-dimension structure of shallow crust,and find the

关键词： potential field directional wavelet transform multidirectional and multiscale edges detection mineral exploration

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