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U-Pb dating of zircon from the bed parallel anatectic granitic intrusion in the Baoban group in Hainan Island and the tectonic implication

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Science china Earth Sciences 2005年第12期48卷 2092-2103页

作者： DING Shijiang1, HU Jianmin2. SONG Biao3.4, CHEN Mulun1, XIE Shengzhou1 & FAN Yuan1 1. geological Surveying institute of Hainan, Haikou 5702.6,{2. 2. institute of Geomechanics, chinese Academy of geological Sciences, beijing 100081,{2. 3. beijing Center of SHRIMP, beijing 10003.,{2. 4. institute of {12., chinese Academy of geological Sciences, beijing 10003.,{2. geological Surveying institute of Hainan Haikou China institute of Geomechanics Chinese Academy of Geological Sciences Beijing China beijing Center of SHRIMP Beijing China institute of geology Chinese Academy of Geological Sciences Beijing China

The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites. U-Pb dating analyses of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using SHRIMP II in the beijing Ion-probe Center, acquire 2.6Pb/2.8U ages of 3.8±3.5 Ma (of granite, 95% confidence level, MSDW=1.2.) and 3.2.9±6.1 Ma (of gneiss, 95% confidence level, MSDW = 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep ther-mal-dynamic process when the Gondwana continent began to break up in the Devonian period.

关键词： Hainan Island, Devonian period, anatectic granite, zircon SHRIMP U-Pb dating.

Forcing mechanism of the Pleistocene east Asian monsoon variations in a phase perspective

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Science china Earth Sciences 2005年第10期48卷 1708-1717页

作者： TIAN Jun1,2. WANG Pinxian1, CHENG Xinrong1, WANG Rujian1 & SUN Xiangjun1,3.1. State Key Laboratory of Marine geology, Tongji University, Shanghai 2.0092. china {2. and Geophysics, chinese Academy of Sciences, beijing 10002., china 3. institute of Botany, chinese Academy of Sciences, beijing 100093. china Tongji University chinese Academy of Sciences

The deep sea records from the ODP Sites 1143.and 1144 in the northern and southern South china Sea (SCS), including foraminiferal δ 18O and δ 13., Opal% and pollen percentage, reveal that the variations of the east Asian monsoon have been closely correlated with the variations of the Earth’s orbital parameters (eccentricity, obliquity and precession) and the global ice volume on orbital scale. All the monsoonal proxies show strong 100 ka, 41 ka and 2. ka cycles. Although G. ruber δ 13. of Site 1143.is coherent with the ETP (ETP= normalized (eccentricity + obliquity-precession) at eccentricity, obliquity and precession bands, most of the coherent relationship focuses on the precession band, and the other monsoonal proxies are coherent with the ETP only at the precession band, which indicate that precession dominates the Pleistocene tropical climate changes. The phase relationship of the monsoonal proxies with the foraminiferal δ 18O implies that the global ice volume changes have played a significant role in modulating the east Asian monsoon climate, at least dominating the winter monsoon. This forcing mechanism of the east Asian monsoon is apparently different from that of the Indian ocean mon-soon. The variations of the east Asian monsoon at the precession band, at least that of the winter monsoon, have been controlled not only by the sensible heating but also by the latent heating of the surface water in the South china Sea.

关键词： South china Sea, ODP, east Asian monsoon, orbital forcing, global ice volume.

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

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Science china Earth Sciences 2005年第7期48卷 1025-1039页

作者： HUANG Fei1, Kealhofer Lisa2. XIONG Shangfa3.& HUANG Fengbao1 1. Nanjing institute of geology and Paleontology,{2. Academy of Sciences,Nanjing 2.0008,china 2. Anthropology and Sociology Department,Santa Clara University,CA 95053.USA 3. institute of geology and Geophysics,{2. Academy of Sciences,beijing 10002.,china Nanjing institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States institute of geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 872. a BP, the Aneurolepidium chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 872. to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 42.0?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3.00 and 2.70 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 2.70 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

A mixed method for measuring low-frequency acoustic properties of macromolecular materials

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 729-739页

作者： LIU Hongwei1,YAO Lei1,3.ZHAO Hong1,3.ZHANG Jichuan2.3.& XUE Zhaohong2.1. National Key Laboratory of Acoustics,institute of Acoustics,{3. Academy of Sciences,{2. 100080,china 2. institute of Chemistry,{3. Academy of Sciences,{2. 100080,china 3. Graduate University of {3. Academy of Sciences,{2. 100049,china National Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing China Graduate University of chinese Academy of Sciences Beijing China institute of Chemistry Chinese Academy of Sciences Beijing China

A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.

关键词： low-frequency acoustic properties,dynamic mechanical properties,Principles of Time-Temperature Superposition,acoustic pipe,sound absorption coefficient.

Discovery of Cu-Zn,Cu-Sn intermetallic minerals and its significance for genesis of the Mianning-Dechang REE Metallogenic Belt,Sichuan Province,china

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Science china Earth Sciences 2006年第6期49卷 597-603页

作者： XIE Yuling1, HOU Zengqian2. XU Jiuhua1, YUAN Zhongxin2. BAI Ge2.& LI Xiaoyu3.1. Civil and Environmental Engineering School, University of Science and Technology {3., {3. 100083.{2. 2. institute of geology, chinese Academy of geological Sciences, beijing 10003.,{2. 3. The 109th geological Team, Sichuan Bureau of Mineral Exploration, Chengdu 610100,{2. Civil and Environmental Engineering School University of Science and Technology Beijing Beijing China institute of geology Chinese Academy of Geological Sciences Beijing China The 109th geological Team Sichuan Bureau of Mineral Exploration Chengdu China

Mianning-Dechang Himalayan REE Metallogenetic Belt in Sichuan Province lies along the western margin of the Yangtze Craton. We have conducted detailed mineralogical studies on ore minerals collected from Maoniuping and Dalucao, the two largest deposits in the belt. With optical microscope, SEM/EDS, and EPMA, three rare intermetallic minerals, i.e., zinccopperite (Cu2.n), Sn- bearing native copper, and Cu-bearing jupiter were found to occur in the main ore along with barite, fluorite, apatite, sulfide and bastnaesite. Since the conditions under which zinccopperite and Sn- bearing native copper formed are quite unique, finding of these minerals, for the first time in domestic REE deposits, has significant implications for the genesis of the ore deposits in which they occur. In comparison with Cu-Zn intermetallic minerals in other occurrences, we propose that the formation of this REE metallogenetic belt is associated with fast upwelling of the Himalayan magma from deep source.

关键词： Mianning-Dechang REE metallogenetic belt, Cu-bearing intermetallic minerals, EPMA, genesis significance, deep source magmatic activity.

Petrogenesis and dating of the Kangding complex,Sichuan Province

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Science china Earth Sciences 2005年第5期48卷 622-634页

作者： CHEN Yuelong 1 , LUO Zhaohua 1 , ZHAO Junxiang, LI Zhihong, ZHANG Hongfei & SONG Biao 3.1. Faculty of Earth Sciences and Natural Resources, china University of Geosciences, beijing 100083. china {3. Faculty of Earth Sciences, china University of Geosciences, Wuhan 43.074, china 3. beijing SHRIMP Center, institute of geology, chinese Academy of geological Sciences, beijing 10003., china Faculty of Earth Sciences and Natural Resources China University of Geosciences Beijing China Faculty of Earth Sciences China University of Geosciences Wuhan China beijing SHRIMP Center Institute of Geology Chinese Academy of Geological Sciences Beijing China

An analysis of major and trace element geochemistry and SHRIMP U-Pb zircon dating of mafic, intermediate, and felsic rocks from the Mianning metamorphic complex of Si- chuan Province was conducted. One of our conclusions is that a majority of the zircons crystal- lized between 72. and 773.Ma in a magmatic regime. The complexes contain early to late Pa- leo-proterozoic relict zircons from ancient continental crust. The oldest age, 2.68 Ma, may rep- resent the basement of the Yangtze block. Overgrowth zircon rims and palingenetic zircons have been observed and dated, and are believed to have formed after crystallization, during Paleozoic and Mesozoic metamorphic-anatexis. We also conclude that depletion of Nb, Ta, HREE, in a spider-diagram normalized to primitive mantle and calc-alkaline association, implies that they formed in island-arc or under-plating settings.

关键词： Kangding complex, zircons, SHRIMP, tectonic setting.

Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area,Shandong Province,china

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Science china Earth Sciences 2006年第1期49卷 77-87页

作者： MA Jinlong1,2. TAO Mingxin2.3.& YE Xianren2.1. Resources and Environmental School, Lanzhou University, Lanzhou 73.000,{3. 2. Key Laboratory of Gas Geochemistry, institute of {2. and Geophysics, chinese Academy of Sciences, Lanzhou 73.000,{3. 3. College of Resources Science & Technology, beijing Normal University, beijing 100875,{3. Resources and Environmental School Lanzhou University Lanzhou China Key Laboratory of Gas Geochemistry Institute of Geology and Geophysics Chinese Academy of Sciences Lanzhou China College of Resources Science & Technology Beijing Normal University Beijing China

Fluids and noble gases of mantle-derived materials are important tracers forthe mantle information. Compositions of primary fluids and noble gases in mantle-derived mineralsfrom the Yishu area, Shandong Province, china, were tested by the methods of heat-bursting andheat-melting respectively. The fluids are mainly composed of CO_2. CO and H_2. which account forabout 90% of the total, and are similar to the mantle-derived rocks from other areas of eastern{3.; ratios of ~3.e/~4He in almost all samples range from 0.82.Ra to 2.74 Ra, whereas^(40)Ar/^(3.)Ar from 2.9.5 to 758.8. Both ranges are much lower than those of the typical oceanmantle-derived samples (such as MORB) and primarily reflect the influences of the atmosphericcomponents and the radiogenic isotopes. Ratios of C/~3.e range from 2..6 x 10~9 to 1050 x 10~9,N_2.Ar from 92. to 56612. and N_2.~3.e from 2.5 x 10~9 to 2. x 10~9, similar to those in westernUnited States and New Zealand which belong to the tectonic plate collision regions. The ratios fallin the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting theinfluences of the atmosphere and the crusts with organic components. Our results suggest that thecomposition of the primary fluids and the isotopic ratios of the noble gases may either reflect theevolution process of mantle-derived rocks connected with the rise and eruption of magma, or theinfluence of the ancient subduction-plate on the continental mantle of this region.

关键词： noble gases, primary fluids, mantle-derived minerals, Yishu area.

Geochemical simulation of the formation of brine and salt minerals based on Pitzer model in Caka Salt Lake

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Science china Earth Sciences 2004年第8期47卷 720-726页

作者： LIU Xingqi1, CAI Keqin2.& YU Shengsong3.1. Nanjing institute of Geography and Limnology, chinese Academy of Sciences, Nanjing 2.0008,{2. 2.{2. University of Geosciences, beijing 100083.{2. 3. institute of Salt Lakes, chinese Academy of Sciences, Xining 810008,{2. Nanjing institute of Geography and Limnology Chinese Academy of Sciences Nanjing China china University of Geosciences Beijing China institute of Salt Lakes Chinese Academy of Sciences Xining China

The geochemical simulation of the formation of brine and salt minerals based on Pitzer model was made in Caka Salt Lake. The evolution of the mixed surface-water and the mineral sequences were calculated and compared with the hydrochemical compositions of the brine and the salt minerals of the deposit in Caka Salt Lake. The results show that the formation temperature of the lake is between 0°C and 5°C, which is well identical with other studies. The mixing of salt-karst water with the surface waters, neglected by the former researchers, is very important to the formation of the lake, indicating that the initial waters resulting in the formation of the lake are multi-source. It is the first time to use Pitzer model in china for making geochemical simulation of the formation and evolution of inland salt lake and satisfactory results have been achieved.

关键词： Pitzer model,Caka Salt Lake,geochemical simulation,salt-karst water.

Timing and history of marine hydrocarbon accumulation in Tarim craton

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chinese Science Bulletin 2002年第S1期47卷 120-127页

作者： ZHAO Jingzhou~(1,2. & LI Qiming~3.1. Department of Petroleum geology, Xi’an Petroleum institute, Xi’an 710065,{2. 2. Research institute of Petroleum Exploration and Development, Petrochina, beijing 100083.{2. 3. Tarim Oilfield Company, Kuerle, Xinjiang 841000,{2. Department of Petroleum geology Xi’an Petroleum Institute Xi’an China Research institute of Petroleum Exploration and Development PetroChina Beijing China Tarim Oilfield Company Kuerle Xinjiang China

Based on the analyses of hydrocarbon inclu-sions, K-Ar dating of authigenic illites and oil/gas-watercontact retrospection as well as other methods, the marineprimary reservoirs in the cratonic region of the Tarim Basinare found to have been formed in the late Caledonian toearly Hercynian, late Hercynian, and Himalayan, and oil andgas adjusted and redistributed in the Yanshanian (Jurassic toCretaceous) and Himalayan (Tertiary). The analyses alsoshow that the remaining primary oil accumulations aremostly formed in the late Hercynian, and the secondary oilreservoirs resulted from the adjustment and redistribution ofthe earlier accumulations during the Yanshanian and Hima-layan (especially late Himalayan), of which the Himalayan isalso the major stage of gas accumulation. The primary oilreservoirs formed in the late Hercynian mostly occur withinthe Paleozoic formation, whereas the secondary reservoirsformed in the Himalayan in the Mesozoic. The late adjust-ment and redistribution of reservoirs in the craton region ofthe Tarim Basin is ubiquitous because of the intensified tec-tonic movements since the Mesozoic, especially Cenozoic andintrusion of the high- to over-mature gas. Furthermore, thelower amplitude of reservoirs in the craton region also makesthem easier to be adjusted and redistributed. Therefore, theremaining paleo-uplift and palaeo-slope developed in rela-tively stable tectonic regions are the main potential areas forthe middle-large marine reservoirs in the Tarim Basin.

关键词： Tarim Basin craton geochronology of hydrocarbon accumulation history of hydrocarbon accumulation marine reservoir primary reservoir secondary reservoir.