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Science China Earth Sciences 2004年第9期47卷 794-803页

作者： ZHANG Yueqiao1. CHEN Wen2, 3 & YANG Nong1.1. institute of Geomechanics, {1. Academy of Geological Sciences, Beijing 1.0081. China 2. institute of geology, {1. Academy of Geological Sciences, Beijing 1.0037, China 3. institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029, China institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China institute of {1. Chinese Academy of Geological Sciences Beijing 100037 China institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China

Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (1.-1. Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 350℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.

关键词： Xianshuihe fault zone, Zheduoshan granitic massif, sinistral shear deformation, 40Ar/39Ar dating, late Cenozoic.

Uncertainty in magnetic activity indices

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Science China(Technological Sciences) 2008年第10期51卷 1659-1664页

作者： XU WenYao institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029, China institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China

Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction. However, the indices suffer from various uncertainties, which limit their application and even mislead to incorrect conclu-sion. In this paper we analyze three most popular indices, Kp, AE and Dst. Three categories of uncertainties in magnetic indices are discussed: "data uncertainty" originating from inadequate data processing, "station uncertainty" caused by in-complete station covering, and "physical uncertainty" stemming from unclear physical mechanism. A comparison between magnetic disturbances and related indices indicate that the residual Sq will cause an uncertainty of 1.2 in K meas-urement, the uncertainty in saturated AE is as much as 50%, and the uncertainty in Dst index caused by the partial ring currents is about a half of the partial ring cur-rent.

关键词： magnetic activity indices Kp AE Dst solar-terrestrial coupling space weather

Indosinian Foreland Fold-and-Thrust Belt Bordering Yunnan and Guangxi, China

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Acta Geologica Sinica(English Edition) 2001年第4期75卷 391-397页

作者： WU Genyao institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029 institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 [?]2Wu Genyao Male born in 1946 graduated from the Department of geology Peking University in 1968 obtained a DSc degree in 1985 now a research professor with the institute of geology and geophysics Chinese Academy of Sciences. His main research interest is regional tectonics and he has been working on the tethysides in South China and adjacent areas since 1987. Tel: (010) 62008118 Fax: (01.) 6201.846 E-mail: dizhikx@***

Recent discoveries of ophiolites indicate that there must be a Palaeotethyan geosuture zone bordering China and Vietnam, which separates the Vietbac block from the South China subcontinent. The Indosinian foreland fold-and-thrust belt bordering Yunnan and Guangxi provided further evidence for the palaeotethysides. The oceanic crust was subducted southwestwards while the magmatic arc migrated northeastwards, and the continent-arc collision occurred in the Late Triassic with the thrusting being extended towards the north or northeast. The features of thrust-nappe structure are discussed, which proved the continental margin of the Palaeotethyan ocean there to be a complicated one. A face-to-face collision occurred first along the NW-striking segment and then along the ENE-striking segment accompanied by transpression or oblique thrusting occurring along the NW-striking one.

关键词： thrust-nappe structure foreland fold-and-thrust belt palaeotethysides border between Yunnan and Guangxi

Si-and alkali-rich melt inclusions in minerals of mantle peridotites from eastern China:Implication for lithospheric evolution

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Science China Earth Sciences 2006年第1期49卷 43-49页

作者： FAN Qicheng1. SUI Jianli2, XU Ping2, LI Ni1. SUN Qian1.& WANG Tuanhua1.1. institute of {1., China Seismological Bureau, Beijing 1.0029, China 2. institute of geology and geophysics, chinese Academy of Sciences, Beijing 1.0029, China 1. institute of {1. China Seismological Bureau Beijing 100029 China 2. institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China

Minerals of spinel- and garnet-facies mantle xenoliths entrained in Cenozoicbasalts from eastern China (North China, Northeastern China and Southeastern China coastal area)contains lots of melt inclusions. Studies on these melt inclusions show that the glass inclusionsare rich in SiO_2 (60%—68%) and alkalis (K_2O+Na_2O = 5%—1.%, especially for K_2O) as well asvolatiles such as H_2O and CO_2 (2%—7%), which belong to dacites and andesites of the high-K calcicalkali series rocks with few shoshonites. High Al and Ca diopside in melt inclusion is the productof melt crystallization at high temperature and pressure, rather than the product ofdevitrification. Results show that these K-rich (in general K_2O > 3%) intermediate-acidic silicatemelt inclusions have characteristics of continent without a genetical link to host basalts and theirphenocrystic minerals. Thus, these trapped melt inclusions represent melts of Mesozoic lithosphericmantle-crust interaction and imply that the continental lithospheric mantle beneath eastern Chinahad undergone fragmentation and recreation processes during the Mesozoic and Cenozoic periods. Thisresult undoubtly provides important implication for the evolution of sub-continental lithospherebeneath eastern China. We propose that these Si- and alkalis-rich melts should be responsible forthe mantle chemical heterogeneity underneath eastern China.

关键词： Si- and alkali-rich melt inclusion, mantle peridotite, lithospheric evolution, eastern China.

Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

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Science China Earth Sciences 2005年第8期48卷 1089-1105页

作者： FAN Qicheng1.2, ZHANG Hongfu1. SUI Jianli1. ZHAI Mingguo1. SUN Qian2 & LI Ni2 1. institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029, China 2. institute of geology, China Seismological Bureau, Beijing 1.0029, China 1. institute of geology and geophysics Chinese Academy of Sciences 100029 Beijing China 2. institute of {1. China Seismological Bureau 100029 Beijing China

On the basis of mineral assemblage, mineralogy, petrology, and major, trace ele-mental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work con-strained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumu-lates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly com-posed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean ter-rain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

关键词： magma underplating, xenolith petrology, geochemistry, cust-mantle boundary constituent, Hannuoba.

The features of gravity field and deep structure in western part of the South Yellow Sea

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chinese Science Bulletin 2000年第8期45卷 759-764页

作者： WANG Qianshen1.& AN Yulin1. institute of {1., chinese Academy of Sciences, Beijing 1.01.1. China 2. chinese University of geology, Beijing 1.0083, China institute of {1. Chinesc Academy of Sciences Beijing China chinese University of {1. Beijing China

The gravity data from the sea region to the west of 1.4° E of the South Yellow Sea have been processed and the feature of gravity fields analyzed. An experience relationship formula on the filter wavelength and corresponding depth has been put forward. Combined with the geological and seismic data, the deep tectonic framework and structural characters as well as possible favourable prospecting district for hydrocarbon in the South Yellow Sea have been discussed and analyzed.

关键词： western part of the South Yellow Sea gravity field deep structure.

Carbon isotope composition and its implications of Lower Cretaceous Aptian-Albian shallow water carbonates in the Cuoqin Basin, North Tibet

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Science China Earth Sciences 2004年第3期47卷 247-254页

作者： ZHU Jingquan1. LI Yongtie2, JIANG Maosheng1.& CHEN Daizhao1.1. institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029, China 2. Research institute of Petroleum Exploration and Development, CNPC, Beijing 1.0083, China chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China CNPC Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China

The d 1.C values of Lower Cretaceous Aptian-Albian platform-type carbonates in the Cuoqin Basin, North Tibet vary between 2.48 and 5.46. The mean value is 3.93. The values are not only provided with positive excursion, but also 1.1. higher than those of con-temporaneous pelagic carbonates which possess pretty high d 1.C values. The origin is ap-proached. During the oceanic anoxic events, a great number of organisms were rapidly buried, causing the increase of the d 1.C value of oceanic total dissolved carbon (TDC) and generally promoting the values of marine carbonates. After that, owing to the organisms undergoing dif-ferent isotopic fractionation in the paleo-ocean with stratified structure, d 1.C values of shallow sea carbonate were obviously higher than those of pelagic carbonates.

关键词： shallow water carbonate, stable carbon isotope, paleooceanography, Aptian-Albian stage, Cuoqin Basin.

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 {1. and Paleontology,chinese Academy of Sciences,Nanjing 21.008,China 2. Anthropology and Sociology Department,Santa Clara University,CA 95053,USA 3. institute of geology and geophysics,chinese Academy of Sciences,Beijing 1.0029,China Nanjing institute of {1. and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States institute of {1. 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 1.000 and 8720 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 8720 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 4200?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 21.0 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 21.0 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.

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 200092, China 2. {1., chinese Academy of Sciences, Beijing 1.0029, China 3. institute of Botany, chinese Academy of Sciences, Beijing 1.0093, China State Key Laboratory of Marine geology Tongji University Shanghai China institute of geology and geophysics {1. Academy of Sciences Beijing China institute of Botany {1. Academy of Sciences Beijing China

The deep sea records from the ODP Sites 1.43 and 1.44 in the northern and southern South China Sea (SCS), including foraminiferal δ 1.O and δ 1.C, 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 1.0 ka, 41.ka and 23 ka cycles. Although G. ruber δ 1.C of Site 1.43 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 1.O 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.

Compositions of heavy minerals in Northeastern China sandlands and provenance analysis

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Science China Earth Sciences 2007年第11期50卷 1715-1723页

作者： XIE Jing1.2 & DING ZhongLi1.1.institute of geology and geophysics, {1. Academy of Sciences, Beijing 1.0029, China 2 Graduate University of {1. Academy of Sciences, Beijing 1.0049, China 1. institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China 2. Graduate University of chinese Academy of Sciences Beijing 100049 China

Sand samples deposited since the Last Glacial Maximum (LGM) from the Hulun Buir, Horqin and Otin-dag sandlands were measured for their assemblages of heavy minerals and chemical compositions of detrital garnets and tourmalines. Heavy mineral assemblages of these three sandlands consist mainly of garnet, ilmenite, epidote and minor amphibole and magnetite. Garnets consist mainly of high Mg type-A ones (58% on average), and minor type-B ones. Toumalines are mainly composed of Mg-rich and minor Fe-rich ones. Compared with those of central-southern Mongolia and central Tarim, these three sandlands are derived from the Phanerozoic rocks of the Central Asian Orogenic Belt and the Archean and Paleoprotorozoic basement rocks of the North China Craton. Our results provide direct evidence that the present-day sands may be reworked from LGM ones. Differences of heavy mineral composi-tions occur between the samples of the three sandlands and Taklimakan Desert, indicating that the material of the western arid regions contributes little to the eastern sandlands.

关键词： heavy minerals,provenance,Northeastern China,garnet,tourmaline