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Modern microbialites and their environmental signifi-cance,Meiji reef atoll,Nansha (Spratly) Islands,South china Sea

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Science china Earth sciences 2008年第4期51卷 608-617页

作者： SHEN JianWei1 & WANG Yue1,2 1 Department of Marine geology, South china Sea Institute of Oceanology Key Laboratory of Marginal Sea geology, South china Sea Institute of Oceanology and Guangzhou Institute of Geochemistry, Chinese academy of sciences, Guangzhou 5103.1, china 2 Graduate University of the Chinese academy of sciences, beijing 100049, china Department of Marine geology South China Sea Institute of Oceanology Guangzhou China Key Laboratory of Marginal Sea geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of the Chinese academy of sciences Beijing China

Meiji (Mischief) coral atoll, in Nansha (Spratly) Islands, South china Sea, consists of an annular reef rim surrounding a central lagoon. On the atoll rim there are either protuberant 'motu' (small coral patch reefs on the rim of atoll) islets or lower sandy cays that contain modern microbialite deposits on the corals in pinnacles and surrounding bottoms of the atoll. Microbialites, including villiform, hairy, and thin spine growth forms, as well as gelatinous masses, mats and encrustation, developed on coral colonies and atoll rim sediments between 0 and 15 m deep-water settings. The microbialites were produced by natural populations of filamentous cyanobacteria and grew on (1) bulbous corals together with Acropora sp., (2) on massive colonies of Galaxea fascicularis, (3. on dead Montipora digitata, and (4) on dead Acropora teres, some hairy microbialite growing around broken coral branches. This study demonstrates that microbial carbonates are developed in coral reefs of South china Sea and indicates that microbial processes may be important in the construction of modern reef systems. The results have significance in the determination of nature and composition in microorganisms implied in the formation ancient microbialites, and permit evaluation of the importance of microbial deposits in mo-dern coral reefs and of 'microbialites' in biogeochemical cycles of modern coral reef systems. The re-sults also provide evidence of modern analogues for ancient microbialites in shallow-water settings, and combine with sedimentological studies of ancient microbialites to understand their controls.

关键词： Microbialite Meiji reef Nansha Island South china Sea

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, china 2. Institute of geology and geophysics, Chinese academy of sciences, beijing 10002., china Correspondence should be addressed to Zhang Jinjiang (email: zhjj@***) Department of geology Peking University Beijing China Institute of geology and geophysics 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, ~23.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.

A challenge to the concept of slip-lines in extrusion tectonics

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Geoscience Frontiers 2011年第1期2卷 23-34页

作者： Yadong Zheng~(a,*),Erchie Wang~b,Jinjiang Zhang~a,Tao Wang~c a Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space sciences, Peking University,beijing 100871,china b Institute of {3. and geophysics,Chinese academy of sciences,beijing 10002.,china c Institute of {3.,Chinese academy of Geological sciences,beijing 10003.,china 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 geophysics Chinese Academy of Sciences Beijing 100029 China Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

Wide-open V-shaped conjugate strike-slip faults in Asia are typically related to extrusion ***,the tectonic model based on the slip-line theory of plasticity has some critical problems associated with *** conjugate sets of slip-lines in plane deformation,according to the theory of plasticity should be normal to each another but,in reality,the angles between the conjugate strike-slip faults,which are regarded as slip-lines in extrusion tectonics in the eastern Mediterranean,Tibet-middle Asia,china and the Indochina Peninsular regions,are always more than 90°(on average～110°) in the direction of contraction. Another problem is that the slip-line theory fails to explain how,in some cases,e.g.,in the Anatolian area in the eastern Mediterranean,the extrusion rate is much higher than the indent *** two major problems are easy to solve in terms of the Maximum-Effective-Moment(MEM) Criterion that predicts that orientations of the shear zones are theoretically at an angle of 54.7°and practically at angles of 55°±10°with theσ- or contractional *** orientations of the strike-slip faults that accommodate extrusion tectonics are,therefore, fundamentally controlled by the MEM *** extrusion is along the MEM-orientations,the extruding rate is normally higher than the indenting rate.

关键词： Extrusion tectonics Slip-line Wide-open V-shaped strike-slip faults MEM-Criterion Strain rate

A new method to prepare clean cuticular membrane from fossil leaves with thin and fragile cuticles

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Science china Earth sciences 2011年第2期54卷 223-227页

作者： WANG Li1,2 & LENG Qin1,3.1 State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of geology and Palaeontology,Chinese academy of sciences,Nanjing 210008,{3. 2 Graduate School of Chinese academy of sciences,beijing 100049,{3. 3.Department of Science and Technology,Bryant University,Smithfield RI 02917,USA State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China Graduate School of Chinese academy of sciences Beijing China Department of Science and Technology Bryant University Smithfield USA

Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to ＂strengthen＂ the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.

关键词： fossil leaf cuticle Metasequoia new method thin and fragile cuticle SEM observation stomatal frequency CO2

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 beijing, beijing 100083. china 2. Institute of {3., Chinese academy of Geological sciences, beijing 10003., china 3. The 109th Geological Team, Sichuan Bureau of Mineral Exploration, Chengdu 610100, china 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 (Cu2Zn), 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.

The variation in the magnetic fluctuation anisotropy across the front boundaries of magnetic clouds and its geomagnetic response

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Chinese Science Bulletin 2002年第10期47卷 863-867页

作者： LIU Rui & WEI FengsiDepartment of geophysics, Peking University, beijing 100871, china Lab for Space Weather, Center for Space Science and Applied Research, Chinese {3. of sciences, beijing 100080, china Department of geophysics Peking University Beijing China Lab for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China

A statistical study of magnetic fluctuations near the front boundaries of magnetic clouds is approached with the method of Minimum Variance Analysis, based on the data of ImpS and Wind spacecraft. New discoveries are that (1) fluctuation anisotropy tends to increase across the front boundaries of magnetic clouds; (2) there is a good correlation between the fluctuation anisotropy and the geomagnetic activity indices; and (3. in some cases, although there is southward field component immediately after the front boundary, Kp index descends (or Dst index ascends) with a corresponding decrease of the fluctuation anisotropy; in other cases with no distinct southward field component, Kp index ascends (or Dst index descends) with a corresponding increase of the fluctuation anisotropy. Thus we suggest that the fluctuation anisotropy might be a useful indicator in diagnosing the magnetic activities of magnetic clouds.

关键词： front boundary of magnetic clouds geomagnetic activity fluctuation anisotropy.

Hydrogen isotopic characteristics and their genetic relationships for individual n-alkanes in plants and sediments from Zoigê marsh sedimentary environment

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Science china Earth sciences 2010年第9期53卷 1329-1334页

作者： DUAN Yi1, ZHENG Chaoyang2 & WU BaoXiang1 1 Key Laboratory of Petroleum Resources Research, Institute of geology and geophysics, Chinese {3. of sciences, Lanzhou 73.000, china 2 Department of geology, Northwest University, Xi’an 710069, china Key Laboratory of Petroleum Resources Research Institute of Geology and Geophysics Chinese Academy of Sciences Lanzhou China Department of geology Northwest University Xi’an China

To understand internal relations of their hydrogen isotopic compositions in typical marsh environment, we, using GC-IRMS analytical technique, measured the hydrogen isotopes of individual n-alkanes in the herbaceous plant, woody plant leaf, and sediments from Zoigê marsh in china. The results show significant differences in the hydrogen isotopic compositions of n-alkanes among the different kinds of plants and the different species in the same kind. δD values of n-alkanes in the herbaceous plants (from -254‰ to -184‰) are lighter than those in woody plant leaf ( from -195‰ to -142‰ ), and the hydrogen isotopic compositions of n-alkanes in K. tibetica P. are lighter than P. pratensis L. The mean δD values of n-alkanes in the sediments from Zoigê marsh reflect that they were derived from herbaceous plants, which is consistent with the peat samples being composed mainly of herbaceous plant remnants. The significant differences in hydrogen isotopic compositions of n-alkanes among the sedimentary samples are caused possibly by environment factors and the difference in input quantity of different herbaceous plants. A certain negative correlation exists between the δ13. and δD values of n-alkanes in the samples, and plant types can be distinguished using the cross plot of δD vs. δ13. values of n-alkanes in the plants. These data and recognitions provide scientific basis for hydrogen isotopic applied research of individual n-alkanes.

关键词： marsh environment plants sediments individual lipids hydrogen isotopes genetic relationship

Climate as the dominant control on C_3.and C_4 plant abundance in the Loess Plateau: Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

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Chinese Science Bulletin 2003年第2期48卷 1271-1276页

作者： GU Zhaoyan, LIU Qiang, XU Bing, HAN Jiamao, yang Shiling, DING Zhongli & LIU Tungsheng Institute of geology and geophysics, Chinese {3. of sciences, beijing 10002., china Correspondence should be addressed to Gu Zhaoyan (e-mail: zgu@ ***) Institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China

Abundance of C3.and C4 photosynthesis plants can be inferred relatively from stable carbon isotopic composi-tion of organic matter in soils. The samples from five sequences of the last glacial-interglacial loess-soil in the Chinese Loess Plateau have been measured for organic carbon isotopic ratios (d 13.org). The organic carbon isotope data show that relative abundance (or biomass) of C4 plants was increased ca. 40% for each sampling site from the last glacial maximum (LGM) to Holocene optimum, and increased southeastward on the Loess Plateau during both periods of LGM and Holocene. Statistic analyses on the steady maximum d 13.org values of Holocene soils and modern climatic data from the Loess Plateau and Inner Mongolia indicate that the C4 plant abundance increases with increasing temperature and decreasing precipitation. The C4 plant abundance is related much closer with mean April tem-perature and precipitation than annual. These results lead us to deduce following conclusions. First, temperature is the major factor for control on variations in C4 plant abundance in the Loess Plateau from the last glacial to interglacial. In the absence of favorable temperature condition, both of low moisture and low atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants in the plateau. Second, d 13.org in the loess-paleosol sequences, as a proxy of the relative abundance of C4 plants in the Loess Plateau, could not be used as an indicator of changes in the summer monsoon intensity unless the tem-perature had changed without great amplitude. Since all C4 plants are grasses, finally, the increase of the C4 plants supports that forest has not been dominant in the ecosystem on the Loess Plateau during Holocene although precipitation and atmospheric CO2 were largely increased relative to those during LGM.

关键词： C3.C4 plants d 13.org Loess Plateau LGM Holocene.

Sulfide-melt inclusions in mantle xenoliths of Hannuoba,china

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Chinese Science Bulletin 1999年第2期44卷 166-170页

作者： XU Jiuhua , CHU Xuelei , ZHOU Yiming , DU YuanfuUniversity of Science and Technology beijing, beijing 100083. china {3. University of Geosciences( beijing) , beijing 100083. china The Research Center of Mineral Resources Exploration , beijing 100101, china Institute of geology, Chinese academy of sciences,{13., china University of Science and Technology beijing Beijing China china University of Geosciences (beijing) Beijing China The Research Center of Mineral Resources Exploration Beijing China Institute of geology Chinese Academy of Sciences Beijing China

Sulfide fluid incluision study on mantle xenoliths of Hannouba has been carried out by EPMA analysis. It is indicated that the Ni/Fe ratios of metal sulfides in sulfide-melt inclusions from Hannuoba seem to be related to host rocks. These data of lherzolite （pentlandite） are obviously higher than those of olivine pyroxenite （mainly pentlandite, partly pyrrhotine）. The LRM analysis shows that sulfur （H2S+SO2） occupies larger proportion in gas composition of CO2 fluid inclusions, generally more than mol 20 %. This may be related to sulfide inclusions which are frequently found.

关键词： mantle xenolith sulfide-melt inclusion EPMA.