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Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science china earth {2. 2008年第5期51卷 654-664页

作者： HU Guang1,2. JIN ZhangDong1 & ZHANG Fei3 1 State Key Laboratory of Loess and Quaternary Geology, Institute of earth Environment, Chinese Academy of sciences, Xi’an 710075, {2. 2.Graduate university of the Chinese Academy of sciences, beijing 100049, {2. 3 College of resources and Environmental Science, Nanjing Agricultural university, Nanjing 2.0095, {2. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China Graduate university of the Chinese Academy of sciences Beijing 100049 China College of resources and Env

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2. the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

Grade and Tonnage Model of Contact　Metasomatic Copper Deposit in china

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Journal of earth Science 2000年第1期19卷 76-80页

作者： Wang Xueping Wei Min faculty of earth {2., china university of geosciences, Wuhan 430074 Yang Lipei Zhao Jingman china mineral Information Research Institute, beijing 100037

Grade-tonnage model is one of the research frontiers of systematical exploration theory. Based on the “Reserve Database of mineral resources in {2. (1997)”, this paper establishes the geological model, grade model, tonnage model, grade-tonnage model and tonnage-sequence model of contact metasomatic copper deposits in {2.. The mathematical properties of these models are described in detail.

关键词： contact metasomatic copper deposit grade model tonnage model grade-tonnage model tonnage-sequence model china.

Identification of 3.5 Ga detrital zircons from Yangtze craton in south china and the implication for Archean crust evolution

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Progress in Natural Science:Materials International 2006年第6期16卷 663-666页

作者： LIU Xiaoming, GAO Shan, LING Wenli, YUAN Honglin and HU Zhaochu (National Key Laboratory of Geological Processes and mineral resources, {2. of earth sciences, china university of geosciences, Wuhan 430074, china Key Laboratory of Continental Dynamics, Department of Geology, Northwest university, Xi' an 710069, china) [a]National Key Laboratory of Geological Processes and mineral resources Faculty of Earth Sciences China University of Geosciences Wuhan China [b]Key Laboratory of Continental Dynamics Department of Geology Northwest University China

The LA-ICP-MS U-Pb dating of hundreds of detrital zircon grains from the Sinian sandstones of Liantuo formation and tillites of Nantuo formation at Sanxia area in Yichang identified 3319-3508 Ma zircon grains. Their 2.7Pb/2.6Pb and 2.6Pb/2.8U ages show excellent agreement (concordia degree 99%-100% ). Their CL images exhibit well-developed oscillatory zoning and the Th/U ratios are within 0.46-0.76, implying that they are igneous zircons which formed during middle-early Archean. These zircons are the oldest ones discovered in Yangtze craton until now. However, the detrital zircons with ages older than 3. 3 Ga in the metamorphic rocks of Kongling group were not found by further investigation, which suggests the presence of crust older than high-grade metamorphic Kongling terrain in Yangtze craton.

关键词： early Archean detrital zircon zircon dating Yangtze craton.

The history of crustal uplift and metamorphic evolution of Panzhihua-Xichang micro-palaeoland, SW china:Constraints on Sm-Nd, ^(40)Ar/^(39)Ar and FT ages of granulites

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Science china earth {2. 2004年第8期47卷 689-703页

作者： XU Shijin1, LIU Wenzhong1, WANG Rucheng1, YU Hangbo1, LI Daming2. WAN Jinglin2.& FANG Zhong1 1. Department of earth sciences and State Key Laboratory for {2. Deposits Research, Nanjing university, Nanjing 2.0093, china 2. Institute of Geology, china Seismological Bureau, beijing 10002., china 1. Department of earth sciences and State Key Laboratory for {2. Deposits Research Nanjing University 210093 Nanjing China 2. Institute of Geology China Seismological Bureau 100029 Beijing China

Panzhihua-Xichang (Panxi) micro-palaeoland is the oldest terrane on the western margin of the Yangtze Block. Some intermediate-basic granulites are considered to be the crys-talline basement of lower crust in the terrane. Granulite-facies metamorphism of the granulites was developed in the period from 1186 Ma to 112. Ma. The origin of granulites was related to the collision orogenic process occurring when the micro-palaeolands merged to form the Rodinia Supercontinent. Amphibolite-facies retrogressive metamorphism of granulites took place in the period from 877 Ma to 82. Ma. This period was consistent with the breakup time of the Rodinia Supercontinent. 40Ar/39Ar ages and fission track (FT) ages of granulites in the Panxi mi-cro-palaeoland show that the vertical movement history of crustal rocks was a slow uplift process of the rigid terrane in the time from Neoproterozoic to Mesozoic. The subduction of India Plate towards Euroasia Plate resulted in the rapid uplift of the Qinghai-Tibetan Block in Cenozoic. Meanwhile, the Qinghai-Tibetan Block moved towards east. Consequently the Panxi terrane was uplifted rapidly. As a result of the collision orogeny between the Qinghai-Tibetan Block and the Panxi terrane, the granulite-facies crystalline basement in this region was exhumed and exposed to the surface.

关键词： granulite,isotope geochronology,crustal uplift movement,Panzhihua-Xichang region,western margin of Yangtze Block.

Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition:Enlightening from carbon isotopes and molecular fossils

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Science china earth {2. 2005年第10期48卷 1656-1665页

作者： GONG Yiming1,2. XU Ran1, TANG Zhongdao1, SI Yuanlan3 & LI Baohua4 1. faculty of earth Science and State Key Laboratory of Geological Processes and {2. resources, china university of geosciences, Wuhan 430074, china 2. Institute of resources & Environments, Henan Polytechnic university, Jiaozuo 454003, china 3. Department of Computer Science, South-Central university for Nationalities, Wuhan 430074, china 4. Laboratory of Marine Geology, Tongji university, Shanghai 2.0092. china faculty of earth Science and State Key Laboratory of Geological Processes and {2. resources china university of geosciences Wuhan china Institute of resources & Environments Henan Polytechnic university Jiaozuo {2. Department of Computer Science South-Central university for Nationalities Wuhan china Laboratory of Marine Geology Tongji university Shanghai china

Studies show positive shifts of inorganic and organic carbon isotope values (δ 13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from ?2..38 (‰ V-PDB) to ?2..14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2.3 X 15%)) values from 0.015 to 0.144, TOC values from 0.02. to 0.2.%, V/Cr values from 0.3 to 2.0, Sr/Ba values from 3.2. to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi sec-tion deposited in carbonate slope facies of Guilin, Guangxi, South china, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacte-rial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the mid-dle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → enhanced chemical and biochemical weathering and pe-dogenesis → wide development of soils → increasing riverine nutrient fluxes in epicontinental sea → from superoligotrophic to eutrophic in epicontinental sea → proliferating of marine phyto-plankton and zooplankton → frequent red tide and anoxia → mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmos-pheric Pco2. climatic cooling and sea level falling c

关键词： mass extinction, bacteria-algae, carbon isotopes, molecular fossils, biodiversity, Late Devonian, Guangxi, South china.

Study of Noble Metal Elements in Lower Cambrian Black Rock Series of Guizhou-Hunan Provinces, china

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Journal of earth Science 1999年第1期18卷 93-96页

作者： Li Shengrong Department of Geology and mineral resources,{2., beijing 100083.Gao Zhenmin Institute of Geochemistry, Chinese Academy of sciences, Guiyang 550002

Systematic analyses of noble metal elements in the Lower Cambrian black rock series of South china are reported. Correlations of w (Os)/ w (Ir), w (Au)/ w (Ir), w (Ag)/ w (Au), w (Pt+Pd)/ w (Os+Ru+Rh+Ir), relations of noble metal and platinum group element (PGE) distribution patterns reveal that the noble metals are not directly from extraterrestrial materials. Studying the data of 9 aspects, the authors conclude that the noble metals were mainly from ultramafic mafic igneous rocks and their enrichment in black rocks is mainly controlled by hydrothermal fluid.

关键词： black shale Au Ag PGE Lower Cambrian Guizhou Hunan provinces china.

Sequence of Ductile Shear Zones in UHP Metamorphic Province with in Dabie Massif,china

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Journal of earth Science 1998年第3期17卷 3-9页

作者： Suo Shutian Zhong Zengqiu faculty of earth {2., china university of geosciences, Wuhan 430074

Structural studies in the Dabie massif show that distribution of strain is extremely heterogeneous and illustrates the pattern of deformation partitioning in the ultra high pressure (UHP) metamorphic province on all scales. Based on the field structural analysis along with microstructural observation, at least five widespread episodes of ductile shear zone systems are identified by using geometric, kinematic and rheological indicators and they constitute a shear zone sequence in the UHP metamorphic province within the Dabie massif (DM), china. Each shear zone system, for example, the UHP eclogite facies shear zone system in the sequence, exhibits its own features including geometric styles, mineral assemblages, metamorphic pt conditions and deformation regimes during the formation of such shear zone system. Detailed macro and micro scopical features of different episodes of the shear zones are given with respect to mechanism of strain localization and deformation partitioning. The tectonic significance during the creation and exhumation of the UHP metamorphic rocks is evaluated briefly, as well. It is argued that the ductile shear zones in the UHP metamorphic province play an important role in the Dabie mountain building geodynamic process.

关键词： ductile shear zone UHP metamorphic province exhumation deformation partitioning Dabie massif.

New type of potassium deposit: Modal analysis and preparation of potassium carbonate

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Science china earth {2. 2005年第11期48卷 1932-1941页

作者： MA Hongwen1, FENG Wuwei1, MIAO Shiding1, WANG Yingbin1 & TIAN Shuxin2.1. National Laboratory of mineral Materials, china university of geosciences,{2. 2.Tianjin Bureau of Geological Survey, Tianjin 300191, china 1. National Laboratory of mineral Materials China University of Geosciences 100083 Beijing China 2. Tianjin Bureau of Geological Survey 300191 Tianjin China

A kind of dolomitic mudstone newly found in North china has high amounts of K2. up to 10wB% in average, and potassium reserve is at superior scale. mineral assemblage of the potassium ore indicates a specific and complicated geological environment under which the po-tassium deposit formed. Modal analysis of the potassium host rock shows that the principal min-erals in the ore include microcline, dolomite, and clay minerals such as illite, illite/smectite mixed layer, and kaolinite, attributable to a new type of insoluble potassium deposits in ore genesis. The experiments in this research demonstrated that with sodium carbonate as flux agent, the potas-sium ore could be decomposed with a proportion as high as 99.4% by calcinations at moderate temperature for no more than 1.5―2.0 h; more than 70% of K2. in the calcined materials were leached into the liquor, and by acidification reaction of the filter liquor, a large amount of impuri-ties such as Fe3+, Ti4+, Mn2., Mg2., and Ca2. were removed with precipitation of alumino-silicious colloid residue, which makes it possible to prepare potassium carbonate of electronic grade from the filter liquor, whereas the alumino-silicious residue could be utilized to make mineral polymer, a new type of inorganic construction structural materials. The current research shows that in-dustrial exploitation and comprehensive utilization of this new type of insoluble potassium re-source are feasible both in economic benefits and environmental kindness with the fairly clean production process as sketched in this paper.

关键词： insoluble potassium ore, dolomitic mudstone, modal analysis, potassium carbonate, mineral polymer

Multi-Layered Low-Angle Ductile Detachment System in Dabie-Sulu UHPM and HPM Belts, china

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Journal of earth Science 1999年第3期18卷 187-193页

作者： Suo Shutian Zhong Zengqiu(faculty of earth {2., china university of geosciences, Wuhan 430074) faculty of earth {2. China University of Geosciences Wuhan 430074

The present-day observed crustal-scale tectonic style of ultrahigh-pressure metamorphic (UH-PM) and high-pressure metamorphic (HPM ) belts in the Dabie-Sulu region was dominantly formedby extensional processes, postdating the Triassic collision between the Sino-Korean and Yangtze cratons. The extensional structures overprinting the previous structures related to contraction that produced the thickened continental crust of the UHPM and HPM belts, in particular display the typical features of a Cordilleran-type metamorphic core complex, in which at least four regionalscale, low-angle ductile shear zones that constitute a detachment system, are recognized in the Dabie region. In the Sulu region, the extensionaI structures show in the form of small-scale domes or a regional-scale SE-dipping pseudo-monocline. The geometry and the kinematics of tbe detachment zones are briefly described and their significance for the exhumation of UHPM and HPM rocks is discussed. It is iniliated that the subhorizontal crustal-scale extensional flow in the middle-lower crust, under amphibolite- to greenschist-facies conditions, was an important tectonothermal process at 2.0- 170 Ma and the exhumation or the UHPM and HPM rocks was achieved at least in part along multi-layered detachment zones. The regional detachment system has been the main factor enabling UHPM and HPM rocks to be brought from middle-lower crustal levels to middle-upper crustal levels.

关键词： detachment system UHPM and HPM rocks exhumation ductile shear zone,Dabie massif Dabie-Sulu region