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Nd isotopic characteristics of Proterozoic metasedimentary rocks and constraints on their provenance in the eastern segment of Central Tianshan Belt, Xinjiang

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Progress in Natural Science:Materials International 2003年第12期 28-33页

作者： LI Qiugen 1, LIU Shuwen 1*, HAN Baofu 1, ZHANG Jian 1 and CHU Zhuyin 2.1. The key laboratory of {2. {3. and Crustal Evolution, ministry of education, School of Earth and Space Sciences, peking university, Beijing 100871, China 2. Institute of geology and Geophysics, Chinese Academy of Sciences, Beijing 10002., China) The key laboratory of {2. {3. and Crustal Evolution Ministry of Education School of Earth and Space Sciences Peking University Beijing 100871 China Institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Sm Nd isotopic characteristics, ε Nd ( t ) values and Nd model ages ( T DM ) of Proterozoic metasedimentary rocks in the eastern segment of Central Tianshan Belt (ESCTB), Xinjiang, are used to constrain the sedimentary provenance as well as to evaluate their tectonic implications. ε Nd ( t ) and T DM values of these samples range from -4.00 to +6.3. and from 1.2. to 2.2. Ga, respectively. These feature values are distinguished from those of Archean Tarim Craton. Their average ε Nd ( t ) values of the Weiya, the Kumishi and the south to the Dikar samples are -2.46, +2.06 and +1.3., respectively. Nd model ages of the Weiya samples vary between 1.86 and 2.2. Ga , but those of the Kumishi and the south to the Dikar samples show a significant concentration at 1.6～1.9 Ga and the youngest Nd model age is 1.2. Ga. Those Nd isotopic characteristics suggest that these metasedimentary rocks could be derived from a significant proportion of Paleoproterozoic crustal source and a participation of young arc materials, rather than Archean Tarim Craton. Furthermore, the data also indicate that these two sources were paleogeographically separated. Thus we can deduce that the Kumishi and the south to the Dikar metasedimentary rocks were formed proximal to the arc side of the back arc basin, but the Weiya metasedimentary rocks were closer to the continental side of the back arc basin.

关键词： Nd isotopic features metasedimentary rocks Xingxingxia group provenance and forming time Tectonic setting the ESCTB of Xinjiang.

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Dating and genesis of the upper Weihe River terraces in Longxi basin,China

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Progress in Natural Science:Materials International 2007年第11期17卷 1334-1340页

作者： Pan Baotian, Liu Xiaofeng, Gao Hongshan, Wang Yong and Li Jijun(key laboratory of Western China’s Environmental System, {2. of {3., Lanzhou university, Lanzhou 73.000, China) key laboratory of Western China's Environmental System Lanzhou University Lanzhou 730000 China

Seven terraces along the Weihe River in Longxi basin have been investigated. These terraces all consist of archetypal duality in structure, namely the floodplain deposits and the layer of gravels overlaid by varying thickness of the loess. By resorting to various dating approaches such as palaeomagnetic, optically stimulated luminescenece (OSL), 14C and loess-paleosol sequence, we provide preliminary timing of these seven terraces along upper Weihe River. Analysis on sedimentation characteristics and dating of these terraces showed that seven terraces may be jointly generated by tectonic uplifts and climatic changes. Tectonic uplifts may accommodate initial river incision, and climatic change may be responsible for processes of subsequent channel widening and aggradation. Aggradation normally occurs during glacial periods, in contrast to down-cuttings during transitions from glacial to interglacial period. Moreover, on the basis of the timings and heights of these terraces, we infer that the long-term rate of river incision was determined to be 0.2.m/kyr during the last 870 kyr, which differs from other river incision rates. This discrepancy may reflect spatio-temporal differentiation of tectonic activities in the Qinling orogenic belt during the Pleistocene.

关键词： loess stratigraphy river terraces climate change Upper Weihe River

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Lithosphere types in North China:Evidence from geology and geophysics

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Science China Earth Sciences 2005年第11期48卷 1809-1827页

作者： QIU Ruizhao1,2. DENG Jinfu3. ZHOU Su3. LI Jinfa4, XIAO Qinghui1,5, WU Zongxu6 & LIU Cui3.1. Institute of geology, Chinese Academy of Geological Sciences, Beijing 10003., China 2. Development and Research Center, China Geological Survey, Beijing 10003., China 3. China university of Geosciences, Beijing 100083. China 4. China university of Geosciences, Wuhan 43.074, China 5. Information Center of {3. of Land and Resources, Beijing 1008{12. China 6. Institute of geology, State Seismological Bureau, Beijing 10002., China Institute of geology Chinese Academy of Geological Sciences Beijing China Development and Research Center China Geological Survey Beijing China China university of Geosciences Beijing China China university of Geosciences Wuhan China Information Center of ministry of Land and Resources Beijing China Institute of geology State Seismological Bureau Beijing China

On the basis of the characteristics of geology and geophysics in North China, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North China platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North China Platform is a remnant of cratonic lithosphere after the North China platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North China craton and even Sino-Korean craton. In the Mesozoic period, the middle and east areas of North China platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North China in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the

关键词： lithospheric types,evidence of geology and geophysics,crust-mantle petrological structure,deep process

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Multi-origin alkanes related to CO_2.rich, mantle-derived fluid in Dongying Sag, Bohai Bay Basin

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Chinese Science Bulletin 2002年第20期47卷 1756-1760页

作者： JIN Zhijun, ZHANG Liuping, ZENG Jianhui & YANG LeiBasin & Reservoir Research Center, university of Petroleum, Beijing 102.49, China key {2. for Hydrocarbon Accumulation Mechanism of Chinese {3. of education, university of Petroleum, Beijing 1 Basin and Reservoir Research Center University of Petroleum Beijing 102249 China key Lab. Hydrocarbon Accumul. Mech. University of Petroleum Beijing 102249 China

With the newly obtained carbon isotope data for the natural gas, a pilot study of multiple-sourced alkanes related to the mantled-derived fluid is presented. The carbon isotope values of alkanes in the Dongying Sag possess the features indicating a general organic origin. However, there are two sub-populations in the isotopic data set, which reflect two specific types of origins. In general, the sub-population with high δ13.CH4 values is related to the CO2.rich, mantle-derived fluid, and it is distributed in the belts where mantle-derived fluid flow and basic volcanic activities have occurred. Geological and geochemical studies demonstrate that this variation of methane carbon isotope values in the Dongying Sag is unrelated with the basin bury and thermal histories, types of source rocks, and reactions between basin fluid and rocks. Mixing of mantle-derived fluid and organic sourced hydrocarbons is probably the cause for the variation.

关键词： mantle-derived fluid organic origin hydrocarbons in-teraction carbon isotope.

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Seismic Image Prediction of Cenozoic Reef-Banks in the Northwestern South China Sea

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Journal of Earth Science 2012年第4期23卷 597-611页

作者：陈平陆永潮王振峰陈雷 key laboratory of Tectonics and Petroleum Resources of {2. of {3. China University of Geosciences Zhanjiang Branch Company of CNOOC Limited

The Cenozoic reef-banks reservoir in Qiongdongnan （琼东南） basin is one of the most profitable targets worthy of prospecting in the deep water area of the northwestern South China Sea. In this study, the characteristics of organic reef-like reflectors in southern uplift area of Qiongdongnan basin are analyzed based on the latest 2. and 3. seismic data. It is found that reef-like reflectors in Qiongdongnan basin show high-amplitude moundy continuous reflection at the top and the bottom, chaotic reflection inside the reef-like reflector and there is obviously speed difference between reef-like reflector body and surrounding rock. Combining the geological setting of reef and comparative analysis, the reef-like reflectors are considered to be the reef-banks. Furthermore, the results show that there are three kinds of reef structures in the southern uplift area of Qiongdongnan basin： the fault controlling structure, the fault flexure structure and the carbonate ramp structure. Each structure has its own grow-units that can reveal the growth process of the reef in order. The distribution of reef-like reflec- tors in space shows an arc belt pattern. According to this, four reef arc belts are identified, and their spatial trends are thought to have a good relationship with the buried fault. The internal structure con- stitution and the growth state of reef-like reflectors are mainly controlled by the geomorphology and monsoon-ocean current. The result has an instructive significance to oil-gas exploration of organic reef not only in Qiongdongnan basin, but also even in deep water areas of the South China Sea.

关键词： northwestern South China Sea reef-like reflector structure constitute control factor.

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An Archean continental block in the Taihangshan and Hengshan regions: Constraints from geochronology and geochemistry

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Progress in Natural Science:Materials International 2002年第8期 10-18页

作者： LIU Shuwen , LI Jianghai, PAN Yuanming, ZHANG Jian and LI Qiugen(1. The key laboratory of {2. {3. and Crustal Evolution, School of Earth and Space Sciences, peking university, Beijing 100871, China 2. department of Geological Sciences, university of Saskatchewan, Saskatoon, SK S7N 5E2. Canada) The key laboratory of {2. {3. and Crustal Evolution School of Earth and Space Sciences Peking University Beijing 100871 China department of Geological Sciences University of Saskatchewan Saskatoon SK S7N 5E2 Canada

Recent research on the tectonothermal evolution and geochronology in the Fuping, Hengshan and Wutaishan metamor-phic complexes, together with the discoveries of a high-pressure granulite belt in the northern margin of the North China Craton (NCC) and high-pressure metapelites in the Jingangku Group of the Wutaishan complex, suggests that there was a Neoarchean to Paleoproterozoic orogenic belt related to collision between the Eastern and Western continental blocks. Comparison of geological, geochronological, tectonothermal and geochemical data between the Fuping and Hengshan complexes suggests these two complexes most likely originated and evolved as a single lithotectonic domain (i.e., the Taihangshan-Hengshan block) during the early evolution of the North China Craton, probably as an active margin to the Eastern Continental Block. The Taihangshan-Hengshan block has been subjected to intensive and extensive tectono-magmatism and high-grade metamorphism related to collision between the Eastern and Weste

关键词： Fuping-Hengshan metamorphic complexes North China Craton geochronological and geochemical evidence Archean continental block collision.

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Microscopic deformation of the Neoarchean oceanic lithospheric mantle: evidence from the Zunhua Neoarchean ophiolitic mélange,North China Craton

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Progress in Natural Science:Materials International 2003年第8期 49-56+87页

作者： HUANG Xiongnan , LI Jianghai, NIU Xianglong and FENG Jun(The key laboratory of {2. {3. and Crustal Evolution, School of Earth and Space Sciences, peking university, Beijing 100871, China) The key laboratory of {2. {3. and Crustal Evolution School of Earth and Space Sciences Peking University Beijing 100871 China

The microstructures of the mantle tectonites in the Zunhua Neoarchean ophiolitic mlange are mainly coarse-mosaicstructures with locally interstitial impregnated melts. Olivine and orthopyroxene occur as residual porphyroclastic blasts, dynamic recrys-tallization neoblasts or elongated to be tabular. The podiform chromitites are mostly strongly deformed with the development of pull-apartstructure. These microstructures are typical high-temperature plastic deformation in oceanic upper mantle resulting from ocean-floorspreading. Besides the high-temperature plastic deformation, undeformed magmatic intrusions such as undeformed podiform chromitite,dunite and pyroxenite intrusions are also preserved in the mantle tectonite. Structures of high-temperature plastic deformation and intensivemagmatic activity prove that the Zunhua ophiolite was formed under fast spreading oceanic ridge, similar to the Oman ophiolite. And themicrostructures of country rocks, such as quartz ribbon, core and mantle structure, dynami

关键词： Neoarchean ophiolitic melange microstructures oceanic upper-mantle structural deformation.

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The zircon SHRIMP chronology and trace elementgeochemistry of the Carboniferous volcanic rocksin western Tianshan Mountains

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Science Bulletin 2005年第19期 83-94页

作者： ZHU Yongfeng, ZHANG Lifei, GU Libing, GUO Xuan & ZHOU Jing The key laboratory of {2. {3. and Crustal Evolution, School of Earth and Space Sciences, peking university, Beijing 100871, China

The genesis of the Carboniferous volcanic rocks in the Dahalajunshan group, mainly consisting of trachytes and trachy-andesites and distributing widely in western Tianshan Mountains, remains to be controversial. It has been proposed to be relevant to “rift” or “plume”. Detailed pe-trology and geochemical data presented in this paper show that these volcanic rocks represent typical continental arc magmatism. The volcanic rocks are mainly trachy-andesitic, and the magma source is enriched in LILE, Th and Pb, and depleted in HFSE and Ce. Trace element geochemical study suggests that the basalts could be modeled by 7%-11% partial melt of garnet lherzolite. The volcanic rocks in the Dahala-junshan group are neither the products of “rift” nor so-called “plume” but represent the continental island arc of the Pa-leo-Southern Tianshan Ocean. The mantle wedge had been modified by the melt generating in subduction zone during a long evolution history of this island arc. The continental crust materials (i.e. mainly sediment on ocean floor) had been added into island arc through melt in subduction zone. Volcanic rocks occurring in different regions might represent magma eruption in different time. The zircon SHRIMP dat-ing indicates that the ages of the basalt varies between 3.4.0 Ma and 3.4.9 Ma. The 13.analyses give an average age of 3.3.7 ±4.5 Ma (MSWD = 1.7). The apparent ages of zircons in trachy-andesite vary between 2.3.0 Ma and 465.4 Ma. All analyses fall on the U-Pb concordant line and are divided into two groups. 8 analyses produce an average age of 3.0}8±4.2.Ma (MSWD = 1.7), which represents the crystal-lizing age of zircon rims in trachy-andesite. The acquired two ages (i.e. 3.4 and 3.3.Ma) belong to the Early Carboniferous and Late Carboniferous epochs, respectively. Thus, the Da-halajunshan group would be separated into several groups with the accumulation of high-quality age dating and data of trace element and isotopic geochemistry, in our opinion.

关键词： zircon SHRIMP island arc Dahalajunshan group Xin-jiang Western Tianshan Mountains

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Chronological and geochemical studies of granite and enclave in Baimashan pluton, Hunan, South China

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Science China Earth Sciences 2007年第11期50卷 1606-1627页

作者： CHEN WeiFeng1, CHEN PeiRong1, HUANG HongYe2. DING Xing1,3.& SUN Tao1 1 State key {2. of Mineral Deposit Research, department of Earth Sciences, Nanjing {3., Nanjing 2.0093. China 2.Research Institute No.2.0}, CNNC, Changsha 410011, China 3.Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China State key laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University Nanjing China Research Institute No.2.0} CNNC Changsha China Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

Zircon LA-ICP-MS U-Pb dating reveals that the Baimashan Pluton is composed mainly of late Indosinian (2.4.5±2.8 Ma-2.9.2.3.8 Ma) biotite granodiorites/monzonitic granites (LIGs) and early Yanshanian (176.7±1.7 Ma) two-micas monzonitic granites (EYGs), and the coeval (2.3.2.4.5 Ma-2.5.1±3.9 Ma) mafic microgranular enclaves (MMEs) are generally found in the former. In addition, the ages of cores within zircons from LIGs and MMEs ranging from 2.1.4±4.0 Ma to 2.6.5±4.1Ma provide evidence of multistage magma intrusion during Indosinian in the study area. Measured 3.10±2..6 Ma of inherited zircon age suggests that there may be recycling Archaean curstal material in existence in this area. LIGs and EYGs share some similar geochemical features: subalkaline and peraluminous granites, enrichment of Th, U, K, Ta, Zr, Hf and LREE but depletion of Ba, Nb, P, Ti and Eu, low εNd(t) values but high (87Sr/86Sr)i ratios, and old T2.M (ca. 1.9-2.0 Ga). The behaviors of incompatible elements and REE are mainly dominated by fractional crystallization of plagioclase, K-feldspar, ilmenite and apatite, but that of Sr isotope mainly controlled by EC-AFC. They are crust-sourced and derived from partial melting of paleo-Proterozoic metagreywackes and related to biotite dehydration melting. LIGs are formed in post-collisional tectonic setting as crustal local extension and thinning during late Indosinian. But EYGs may be evolved products of congeneric granitic magma with LIGs formed in late Indoinian, which were emplaced again when crust underwent extensive thinning and extension in post-orogenic tectonic setting during Yanshanian in SC after undergoing EC-AFC. MMEs should be cognate enclaves and derived from liquid immiscibility of host magma.

关键词： granite,mafic microgranular enclave,zircon LA-ICP-MS dating,lithogenesis,EC-AFC

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基于流域单元的泥石流区域危险性评价

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山地学报 2006年第2期24卷 177-180页

作者：王晓朋潘懋徐岳仁北京大学造山带与地壳演化教育部重点实验室北京大学造山带与地壳演化教育部重点实验室北京大学地球与空间科学学院北京100871

进行泥石流区域危险性评价时,首先要选取合适的单元作为评价单元。在前人的研究成果中已有多种评价单元,如栅格单元、斜坡单元、单一条件单元等。作者认为国内评价工作中常采用的栅格单元、行政区划单元都没有体现泥石流发生特定的地貌... 详细信息

进行泥石流区域危险性评价时,首先要选取合适的单元作为评价单元。在前人的研究成果中已有多种评价单元,如栅格单元、斜坡单元、单一条件单元等。作者认为国内评价工作中常采用的栅格单元、行政区划单元都没有体现泥石流发生特定的地貌条件,故提出以流域为评价单元的思路。根据水文学D8方法,介绍了在计算机协助下基于DEM数据自动完成流域单元划分的方法,并以辽宁省鞍山市岫岩满族自治县作为实例,将全区划分为102.个流域单元。将流域划分结果与历史灾害点位置相对比,每个流域内基本上只包含一个灾害点,该情况说明流域划分精度满足研究工作需要。在此基础上利用人工神经网络进行泥石流区域危险性评价。结果显示,以流域作为评价单元能充分体现泥石流发生的地貌特征和物理机制,利于评价指标取值,而且危险性结果与实际情况吻合较好,可为政府部门制定减灾防灾决策提供参考。

关键词：泥石流区域危险性评价流域单元

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