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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 geology,{2. Seismological Bureau, beijing 100029,{2. 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029,{2. institute of geology China Seismological Bureau Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing 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_2.+Na_2. = 5%—11%, especially for K_2.) as well asvolatiles such as H_2. 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_2. > 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.

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. {2. of geology and geophysics, chinese academy of sciences, beijing 100029, china 3. {2. of Botany, chinese academy of sciences, beijing 100093, china Tongji University chinese academy of {2.

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 13C, 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 13C 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.

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, {2. 100083, china 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029, china Research institute of Petroleum Exploration and Development Petrochina Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing 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.

Nonlinear analysis on the coupling process of electromagnetic vibrator and earth

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Science china Earth sciences 2005年第8期48卷 1175-1182页

作者： CHEN Zubin1,2. TENG Jiwen2. LIN Jun1, ZHANG Linhang1 & JIANG Zhongjin1 1. institute of Intelligent Instrument & Measurement Control Technology, Jilin University, Changchun 13002., china {2., chinese academy of sciences, beijing 100029, china institute of Intelligent Instrument & Measurement Control Technology Jilin University Changchun China institute of geology & {2. Chinese Academy of Sciences Beijing China

The linear model based on the hydraulic pressure vibrator has been no longer adaptable to the electromagnetic vibrator. In order to realize the effective transmission of the limited energy from the vibrator to the ground, it is important to study the coupling model of the electromagnetic vibrator and the earth. In this paper, a nonlinear restore term was introduced to the coupling model because of the existence of a large amount of harmonics in the vibrator baseplate. The nonlinear vibration analysis was applied to the model by the multiscale method. In the course of energy transmission from the vibrator to the ground, ultraharmonic resonance was used to explain the generation of harmonics. An improved scheme was advanced to select the cross correlation reference signal in the vibrator seismic exploration. Good application results were obtained in field experiments.

关键词： vibrator, coupling model, electromagnetic, nonlinear vibration.

Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

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chinese Science Bulletin 2003年第B6期48卷 37-41页

作者： GE Shulan~(1,2.3), SHI Xuefa~1 & HAN Yibing~1 1. Key Laboratory of Marine Sedimentology and Environmental geology, First institute of Oceanography, State Oceanic Administration. Qingdao 2.6061.{2. 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029.{2. 3. Graduate School. chinese academy of sciences, beijing 100039.{2. Key Laboratory of Marine Sedimentology and Environmental geology First Institute of Oceanography State Oceanic Administration Qingdao China institute of geology and {2. Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172.surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe *** L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East china Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are *** the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

关键词：中国黄海表面沉积物磁化率等值线长江黄河旋涡沉积区循环系统

Structural pattern of eastern Himalayan syntaxis in Namjagbarwa and its formation process

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Science china Earth sciences 2004年第2期47卷 138-150页

作者： ZHANG Jinjiang, Jl Jianqing, ZHONG Dalai, DING Lin & HE Shundong1. Department of geology, Peking University, beijing 100871,{2. 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029,{2. Correspondence should be addressed to Zhang Jinjiang (email: zhjj@***) Department of geology Peking University Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing China

The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62.60 Ma, ~2. Ma and ~13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology

关键词： Namjagbarwa, eastern Himalayan syntaxis (EHS), structural pattern, formation process, structural chronology.

Carbon isotope ratios of C_(4) plants in loess areas of North china

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Science china Earth sciences 2006年第1期49卷 97-102页

作者： WANG Guoan1,2.3, HAN Jiamao 2. ZHOU Liping3, XIONG Xiaogang4, TAN Ming2. WU Zhenhai5 & PENG Jun6 1. Department of Plant Nutrition, china Agricultural University, beijing 100094, china 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029, china 3. College of Environmental sciences, MOE Laboratory for Earth Surface Processes, Peking University, beijing 100871, china 4. institute of Botany, chinese academy of sciences, beijing 100093, china 5. Northwest Sci-Tech University of Agriculture and Forestry, Yangling 712.00, china 6. Network Center, china Agricultural University, beijing 100094, china Department of Plant Nutrition China Agricultural University Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing China College of Environmental sciences MOE Laboratory for Earth Surface Processes Peking University Beijing China institute of Botany Chinese Academy of Sciences Beijing China Northwest Sci-Tech University of Agriculture and Forestry Yangling China Network Center China Agricultural University Beijing China

Carbon isotope ratios (δ^(13)C) of 89 C_4 plant samples were determined fromthe loess area in North china. δ^(13)C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13)C values of C_4 plants show a slight decreasingtrend. The δ^(13)C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3 species.

关键词： C4 plants, carbon isotope ratios, loess area.

Crust and uppermost mantle structure of the Ailaoshan-Red River fault from receiver function analysis

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Science china Earth sciences 2006年第10期49卷 1043-1052页

作者： XU Mingjie1, WANG Liangshu1, LIU Jianhua2. ZHONG Kai1, LI Hua1, HU Dezhao1 & XU Zhen1 1. Department of Earth sciences, Nanjing University, Nanjing 2.0093, china 2. {2. of geology and geophysics, chinese academy of sciences, beijing 100029, china Department of Earth sciences Nanjing University Nanjing China institute of geology and {2. Chinese Academy of Sciences Beijing China

S-wave velocity structure beneath the Ailaoshan-Red River fault was obtained from receiver functions by using teleseismic body wave records of broadband digital seismic stations. The average crustal thickness, Vp/Vs ratio and Poisson’s ratio were also estimated. The results indicate that the interface of crust and mantle beneath the Ailaoshan-Red River fault is not a sharp velocity discontinuity but a characteristic transition zone. The velocity increases relatively fast at the depth of Moho and then increases slowly in the uppermost mantle. The average crustal thickness across the fault is 36―37 km on the southwest side and 40―42.km on the northeast side, indicating that the fault cuts the crust. The relatively high Poisson’s ratio (0.2.―0.2.) of the crust implies a high content of mafic materials in the lower crust. Moreover, the lower crust with low velocity could be an ideal position for decoupling between the crust and upper mantle.

关键词： receiver function, Ailaoshan-Red River fault, velocity structure, Poisson's ratio, crust and upper mantle.

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 Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space sciences, Peking University, beijing 100871,{2. 2. institute of geology and geophysics, chinese academy of sciences, beijing 100029,{2.) The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education School of Earth and Space Sciences Peking University Beijing 100871 China institute of geology and {2. 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 +6.36 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 +1.37, 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.