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Petrogenesis and significance of early Yanshanian syenite-granite complex in eastern Nanling Range

Science china Earth Sciences 2005年第7期48卷 912-924页

作者： CHEN Peirong1, ZHOU Xinmin1, ZHANG Wenlan1, LI Huimin2. FAN Chunfang1, SUN Tao1, CHEN Weifeng1 & ZHANG Min1 1. State Key Laboratory of Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 2.0093. china 2. Tianjin {4. of {2. and Mineral Resources, china geological Survey, Tianjin 3.0170, china State Key Laboratory of Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China Tianjin institute of geology and Mineral Resources China Geological Survey Tianjin 300170 China

In the eastern Nanling Range there exists the early Yanshanian syenite-granite assemblage. A representative example is the Pitou-Tabei complex composed of the Tabei syenite pluton and the Pitou syenogranite pluton in southern Jiangxi Province. U-Pb zircon dating yields ages of 188.6±2.2.Ma for the Tabei pluton and 186.3.1.1 Ma for the Pitou pluton. The Tabei syenite is characterized by relatively low SiO2.content (62.4.% - 68.75%), high alkalis (K2.+Na2. = 10.56%-11.96%), low percent K2./Na2. ratios (0.56-0.93., metaluminous fea- ture (A/CNK = 0.80-1.00), enrichment in LILE (Rb, Ba, K) and HFSE (Th, U, Nb, Ta, Zr, and so on), weakly negative to positive Eu anomalies (δ Eu = 0.63.1.82., relatively low (87Sr/86Sr)i (0.704.2.0.7054.), and relatively high ε Nd(t) (3.14.3.52.. The Pitou syenogranite is charac- terized by high silicon content (SiO2.= 71.06%-76.2.%), relatively low alkalis (K2.+Na2. = 8.10%-9.80%), high percent K2./Na2. ratios (1.2.-1.94., metaluminous feature (A/CNK = 0.94.1.07), enrichment in Rb, Th (U), K, depletion in Ba, Nb, Ta, Sr, P , Zr, Ti, high ΣREE (av- eraging 4.1.03.μg/g), strong negative Eu anomalies (δ Eu = 0.2.-0.3.), relatively high (87Sr/86Sr)i (0.70805-0.70912., and relatively low ε Nd( t ) (?5.3.-?6.2.). The Tabei syenite and Pitou syenogranite both have the characteristics of A-type granites. The former is considered to be from the asthenosphere mantle, and the latter was the product of the crust-mantle mixture. They both were probably formed in a rifting setting.

关键词： syenite-granite assemblage single zircon U-Pb age rifting environment Nanling Range.

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Metallogenic characteristics of epithermal gold deposits in Tianshan, Xinjiang, china

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chinese Science Bulletin 1999年第S2期44卷 138-139页

作者： FENG Jianzhong~1, FU Shuixing~2. WU Dewen~3.and YANG Zian~3.1. Department of geology, Peking University, Beijing 100871, china 2. Beijing {2. of geology for Mineral Resources, Beijing 100012. china 3. Center of Remote Sensing for geology, CNNC, Beijing 101601, china Department of geology Peking University Beijing 100871 China Beijing institute of geology for Mineral Resources Beijing 100012 China Center of Remote Sensing for geology CNNC Beijing 101601 China

TIANSHAN in southern Xinjiang belongs to the Paleozoic island arc system in which volcanic rocks are extensively distributed. A series of epithermal gold deposits such as the Axi, Xitan, Cuiling andShuangfengshan gold deposits have been discovered. 1 geological settings of epithermal gold deposits in Tianshan, southern Xinjiang Tianshan in southern Xinjiang belongs to the Paleozoic island arc system. To its north is the Kazakhstan plate, and to its north is the Tarim plate. From west to east, the tectonic units are characterizedby Yili island arc, southern Tianshan arc-basin, Jiaoluotage island arc and Xingxingxia island arc. TheEW-trending Tianshan ore belt is controlled by Kanggurtag geosuture. In its west part, it is controlled byShenglidaban geosuture. The linear structure is NNW-trending; from north to south, the faults

关键词： metallogenic characteristics gold deposits Tianshan Xinjiang.

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Tectonic setting of the Helong Block:Implications for the northern boundary of the eastern North china Craton

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Science china Earth Sciences 2005年第10期48卷 1599-1612页

作者： ZHANG Yanbin1, WU Fuyuan1, ZHAI Mingguo1 & LU Xiaoping1,2.1. institute of geology and Geophysics, {2. Academy of Sciences, P.O. Box 982., Beijing 10002., china 2. Regional geological and Mineral Resources Survey of Jilin Province, Changchun 13.062. china institute of geology and Geophysics {2. Academy of Sciences Beijing{3. Regional geological and Mineral Resources Survey of Jilin Province Changchun china

LA-ICP-MS zircon U-Pb dating indicates that the Bailiping granitic pluton was em-placed during Late Paleozoic to Early Cretaceous (2.5―116 Ma) by four distinct magmatic epi-sodes, arguing against the previous thought that the Bailiping granites were emplaced during Archean, Proterozoic or Early Paleozoic. It is suggested that the so-called Archean Jincheng-dong granite-greenstone belt, mainly composed of Bailiping granites, should be broken down. Sr-Nd isotopic compositions of the Bailiping granites are similar to those of the Phanerozoic granites in the Xing’an-Mongolian orogenic belt, suggesting that their parental magmas were mainly derived from a juvenile crust with some contamination of ancient crustal materials during magma rising and/or emplacement. Therefore, the basement of the Helong Block is similar to that in the northern Xing’an-Mongolian Orogenic Belt, but different from that of the North china Craton. It is proposed that the Archean Jinchengdong complex in this area is probably an exotic slice from the North china Craton, which indicates that the Fu’erhe-Gudonghe Fault, located in northern part of the Helong area, is not the boundary between the North china Craton and the Xing’an-Mongolian Orogenic Belt. The possible boundary should be located further southward more than 50 km and near the Baitoushan volcano.

关键词： LA-ICPMS ziron U-Pb dating, Bailiping complex, Helong Block, North china Craton, Sr-Nd isotope.

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SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

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Science china Earth Sciences 2010年第5期53卷 657-664页

作者： ZHAI QingGuo1 WANG Jun1, LI Cai2.& SU Li3.1 institute of geology, {2. Academy of {4. Sciences, Beijing 10003., china 2.College of Earth Sciences, Jilin University, Changchun 13.061, china 3.The {4. Laboratory Center and State Key Laboratory of {4. Processes and Mineral Resources, china University of Geo- sciences, Beijing 100083. china 1. institute of geology Chinese Academy of Geological Sciences Beijing 100037 China2. College of Earth Sciences Jilin University Changchun 130061 China3. The Geological Laboratory Center and State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 4.7±4.Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.2.2.15 to 0.2.2.57, with εHf(t) values of 5.02.0.2., indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

关键词： Qiangtang cumulate gabbro SHRIMP dating Hf isotope

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Discovery of Early Triassic conodonts in western Gangdisê and the establishment of the Tangnale Formation

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Science china Earth Sciences 2007年第12期50卷 1767-1772页

作者： ZHENG YouYe1, XU RongKe1,2. WANG ChengYuan3. MA GuoTao1, LAI XuLong1, YE DeJin2. CAO Liang1 & LIANG JiWei4.1 Faculty of Earth Resourse,{3. University of Geoscience, Wuhan 4.0074.{3. 2.Research {2. of geological Survey of Gansu Province, Lanzhou 73.050,{3. 3.Nanjing {2. of geology and Palaeontology, {13. Academy of Sciences, Nanjing 2.0008,{3. 4.Department of geology, Northwest University, Xi’an 710069,{3. 1. Faculty of Earth Resourse China University of Geoscience Wuhan 430074 China 2. Research institute of geological Survey of Gansu Province Lanzhou 730050 China 3. Nanjing institute of geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China 4. Department of geology Northwest University Xi’an 710069 China

Most geologists believe that there are no Early and Middle Triassic strata in the W. Gandisê stratigraphic subregion, but the present authors have found Early Triassic conodonts for the first time in the Shiquanhe area, including five conodonts genera (Form genera): Pachycladina, Neohindeodella, Cornudina, Hadrodontina and Hibbardella sp. etc. Then we affirm that Early Triassic deposits exist in the Gandisê stratigraphic subregion, and establish the Tangnale Formation. The conclusion is new important complementary basal data for Triassic stratigraphy division of Gangdisê, reconstructing palaogeography and studying Gangdisê from Paleozoic to Mesozoic island-arc evolution and transi-tion.

关键词： Conodonts, Early Triassic, western Gangdisê

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SHRIMP ages of detrital zircons from the Changcheng System in the Ming Tombs area,Beijing:Constraints on the protolith nature and maximum depositional age of the Mesoproterozoic cover of the North china Craton

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chinese Science Bulletin 2003年第22期48卷 2500-2506页

作者： WAN Yusheng1,2. ZHANG Qiaoda1 & SONG Tianrui1 1. institute of geology, {2. Academy of {4. Sciences, Beijing 10003., china 2. Beijing SHRIMP Laboratory, Beijing 10003., china Correspondence should be addressed to Wan Yusheng (e-mail: wanyusheng@***) institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

The Mesoproterozoic Changcheng System is widely distributed in the North china Craton. Determining its time of deposition and sources is important to understand the Precambrian crustal evolution of the North china Craton. This paper suggests age distribution patterns for detrital zircons from clastic sediments of the Changcheng System in the Ming Tombs area, Beijing. Samples of feldspar-bearing sandstone (CHc-2. and pure sandstone (CHc-9) were collected from the Changzhougou Formation, which constitutes the basal part of the Changcheng System. Detrital zircons show an age range from 2.3. to 2.60 Ga. However, sample CHc-9 in the upper Changzhougou Formation also contains some zircons with ages of 1.9-1.8 Ga and 2.3.2.1 Ga. The age patterns lead to the following conclusions: (1) Most of the detrital material came from a source area composed predominantly of ~2.5 Ga continental crust of the North china Craton; (2. 1.9-1.8 Ga reflects the age record of Palaeoproterozoic continent-continent collisional event in the North china Craton; and (3. the oldest age for deposition of the Changcheng System is 1.8 Ga.

关键词：锆石原岩中国北部地区地壳演变

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CARBONATITES FROM THE EASTERN HIMALAYAN SYNTAXIS: PETROLOGY AND TECTONIC IMPLICATIONS

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地学前缘 2000年第S1期7卷 10-11页

作者： Liu Yan 1, Zhong Dalai 2. Ji Jianqing 3.1 institute of geology, {2. Academy of {4. Sciences, Beijing 10003., china 2.institute of geology & Geophysics, {2. Academy of Sciences, Beijing 10002., china 3.Department of geology, Pek

Most carbonatites occur in relatively stable, intra\|plate areas but some are found to occur in near to plate margins and may be linked with plate separation (Woolley, 1989). Although many carbonatites have been discovered to occur in the orogenic belts in recent years, most of these rocks are related to post\|orogenic magmatism, that is, the rocks occur in the specially extensional setting. Therefore it is unusual that such magmatic rocks occur in the typical convergent environment. Here we report carbonatites and associated ultramafic and mafic rocks in the core of the eastern Himalayan syntaxis. The eastern Himalayan syntaxis consists of three tectonic units: the Gangdise, the Yarlung Zangbo, and the Himalayan units, each of which is bounded by faults (Liu & Zhong, 1997). The Himalayan unit, the northernmost exposed part of the Indian plate, is divided into two complexes, the amphibolite facies complex in the south and the granulite facies complex in the north. The granulite facies complex in the Himalayan unit have been argued to experience high\|pressure metamorphism and represent materials buried to upper\|mantle depths (Liu & Zhong, 1997). The carbonatites and associated ultramafic and mafic rocks only occur in the granulite facies rocks and are divided into two belts: northern and southern *** northern belt extends at least 3.km, and is about 2.km in width. The southern belt extends several kilometers, and is 3.m or so in width. Each belt consists mainly of differently compositional dykes, extending parallel to gneissosity of granulite facies gneiss. Carbonatitic agglomerates are observed in the northern belt. From the center of carbonatite dykes to country rocks, five types of rock are observed: the center parts of carbonatites, the rim parts of carbonatites, ultramafic and mafic rocks, altered rocks and country rocks. The gneissosity of country rock was deformed by intrusion of dykes.

关键词： Eastern Himalayan Syntaxis carbonatites ultramafic rocks carbonatitie magmatism convergent environment

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Distribution and characteristics of gravelly soil liquefaction in the Wenchuan M_s 8.0 earthquake

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 167-175页

作者： Cao Zhenzhong1,Hou Longqing2.Xu Hongmei2.and Yuan Xiaoming1 1. institute of Engineering Mechanics,{3. Earthquake Administration,Harbin 150080,{3. 2. East china institute of Technology,Fuzhou 3.8}000,{3. institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China

In this paper,a distribution map of gravelly soil liquefaction that was caused by the Wenchuan M8.0 earthquake in china is proposed based on a detailed field investigation and an analysis of geological soil profiles. The geological background of the earthquake disaster region is summarized by compiling geological cross sections and borehole logs. Meanwhile,four typical liquefied sites were selected to conduct sample drillings,dynamic penetration tests (DPT),and shear wave velocity tests,to understand the features of liquefied gravelly soil. One hundred and eighteen (118) liquefied sites were investigated shortly after the earthquake. The field investigation showed:(1) sandboils and waterspouts occurred extensively,involving thousands of miles of farmland,1{4. villages,eight schools and five factories,which caused damage to some rural houses,schools,manufacturing facilities and wells,etc.; ({4. the Chengdu plain is covered by a gravelly soil layer with a thickness of 0 m to 54. m according to the geological cross sections; (3. there were 80 gravelly soil liquefied sites in the Chengdu plain,shaped as five belt areas that varied from {4. km to 4. km in length,and about ten gravelly soil liquefied sites distributed within Mianyang area; and (4. the grain sizes of the sampled soil were relative larger than the ejected soil on the ground,thus the type of liquefied soil cannot be determined by the ejected soil. The gravelly soil liquefied sites are helpful in enriching the global database of gravelly soil liquefaction and developing a corresponding evaluation method in further research efforts.

关键词： gravelly soil liquefaction borehole soil profile geological cross section grain size distribution Wenchuan earthquake

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geological analysis and physical modeling of structural pumping in high effective formation of Kela 2.gas field

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Science china Earth Sciences 2006年第10期49卷 1070-1078页

作者： ZHAO Wenzhi1, WANG Hongjun1, SHAN Jiazeng2. WANG Zecheng1 & XU Dafeng1 1. Research institute of Petroleum Exploration and Development, Petrochina, Beijing 100083.{2. {4. and Geophysics, chinese Academy of Sciences, Beijing 10002.,{2. 1. Research institute of Petroleum Exploration and Development Petrochina Beijing 100083 China 2. institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

In a 3.D closed geological body, in case “structural expanding” inside is induced by stress, it can produce the pressure difference between the expanding cell and surrounding rock, then generate a pumping force directed toward the cell and accelerate the directional flow of fluid in the strata. The structural style and conditions of gas reservoir-formation in the Kuqa depression are favorable to the structural pumping. According to similarity principle, a physical modeling of structure formation and gas filling process of the Kela 2.gas field has justified the occurrence of structural pumping and its important role in gas-reservoir formation with high efficiency under the compressive and well-sealed circumstance. Therefore, authors propose that structural pumping is an important mechanism of gas reservoir-formation with high efficiency in the Kuqa depression.

关键词： Kela 2 gas field, structural pumping, gas-reservoir formation mechanism, high efficiency,physical modeling.

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High-resolution climate variability of southwest china during 57―70 ka reflected in a stalagmite δ^(18)O record from Xinya Cave

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Science china Earth Sciences 2007年第8期50卷 1202-1208页

作者： LI TingYong1, YUAN DaoXian1,2. LI HongChun1,3.,YANG Yan2. WANG JianLi1, WANG XinYa1, LI JunYun1, QIN JiaMing2. ZHANG MeiLiang2.& LIN YuShi2.1 College of Geographical Science, Southwest University, Chongqing 4.0715, china 2.Karst Dynamics Laboratory, institute of Karst {2., chinese Academy of geological Sciences, Guilin 54.004. china 3.Department of Earth Sciences, Cheng-Kung University, Tainan 70101, Taiwan, china 1. College of Geographical Science Southwest University Chongqing 400715 China 2. Karst Dynamics Laboratory Institute of Karst Geology Chinese Academy of Geological Sciences Guilin 541004 China 3. Department of Earth Sciences Cheng-Kung University Tainan 70101 Taiwan China

A 2.-cm-long stalagmite (XY2. from Xinya Cave in northeastern Chongqing of china has been ICP-MS 2.0Th/U dated, showing a depositional hiatus at 2.3.cm depth from the top. The growth of the 2.3.2. cm interval determined by four dates was between 57 ka and 70 ka, with a linear growth rate of 0.02. mm/a. We have analyzed 190 samples for δ 18O and δ 13., mostly in the 2.3.2. cm part. The δ 18O and δ 13. values between 57 ka and 70 ka reveal decadal-to-centennial climatic variability during the glacial in-terval of Marine Isotope Stage 4.(MIS4., exhibiting much higher resolution than that of the published Hulu and Dongge records during this interval. Speleothem δ 18O in eastern china, including our study area can be used as a proxy of summer monsoon strength, with lighter values pointing to stronger summer monsoon and higher precipitation, and vice versa. Two decreases in the δ 18O signature of XY2.record around 59.5 and 64.5 Ka are argued to correspond to the Dansgaard-Oeschger (D-O) events 17 and 18 respectively. The Heinrich event 6 (H6) can be identified in the record as a heavy δ 18O peak around 60 ka, indicating significant weakening of the monsoon in Chongqing during the cold period. The XY2.δ 18O record shows very rapid change toward to the interstadial condition of the D-O event, but more gradual change toward to the cold stadial condition. This phenomenon found in the Greenland ice core records is rarely observed so clearly in previously published speleothem records. According to SPECMAP δ 18O record, the glacial maximum of MIS 4.was around 64.5 ka with the boundary of MIS 3.4.around 60 ka. Unlike the marine record, the speleothem record of XY2. china, exhibits much high fre-quency variations without an apparent glacial maximum during MIS 4. However, the timing of MIS 3.4.boundary seems to be around 60 ka when the H6 terminated, in agreement with the marine chronology. The growth period of sample XY2.during glacial times probably reflects a local karstic routi

关键词： stalagmite U-series dating oxygen isotope records MIS4 D-O cycles H6 event Chongqing china

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