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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, Chinese Academy of Sciences, Beijing 100029, China 2. Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Res. Inst. Petroleum Explor./Devt. CNPC Beijing 100083 China

The d 13C 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 1.17 higher than those of con-temporaneous pelagic carbonates which possess pretty high d 13C 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 13C 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 13C 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.

Characteristics of chlorine isotope distribution and analysis on sylvinite deposit formation based on ancient salt rock in the western Tarim Basin

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Science China Earth Sciences 2005年第11期48卷 1913-1920页

作者： TAN Hongbing1,2, MA Haizhou1, XIAO Yingkai1, WEI Haizhen1,2, ZHANG Xiying1 & MA Wandong1 1. Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China 2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China Institute of Salt Lakes Chinese Academy of Sciences Xining China Graduate School of the Chinese Academy of Sciences Beijing China

During formation of the Tarim Basin, there repetitively happened seawater invasion for it was ever connected with wide Paleo-mediterranean Sea. At the same time, for the applica-tion of tectonic and paleoenvironmental condition, the basin deposits many sequences of thick strata of evaporites, especially in its two largest subbasins of Kuqa in the north and Shaqa in the southwest. Therefore, the western Tarim Basin has been considered to be a favorable location to prospect ancient sylvinite deposit. But it is unfortunate that the Br×103/Cl ratio, as a common geochemical index to uncover clues of sylvinite deposit, is almost invalid to indicate the stage of ancient brine condensation for very low content of bromine in salt rock samples (less than 10?6 commonly) in the western Tarim Basin evaporites. Fortunately, we noticed recently that the val-ues of chlorine isotope (δ 37Cl value) for salt rock samples follow some clear laws from place to place, which in the Shaqa subbasin, all δ 37Cl values of salt rock samples behaved negatively and on the contrary, they all surprisingly showed positive values in the Kuqa subbasin. Based on conclusions of previous research and referring to the ratios of Br×103/Cl for salt rock or brine samples, we proved that the chlorine isotope (δ 37Cl) could be used as an effective index to find ancient sylvinite deposit in those evaporites rock basin with low content of Br element back-ground, such as the Tarim Basin. Thus according to the new index of chlorine isotope, we con-clude that the concentration of ancient brines formed ancient salt rocks is much more concen-trated in the Shaqa subbasin than that in the Kuqa subbasin. Particularly, the δ 37Cl value of salt rock in Kashi depression of the western Shaqa subbasin is greatly negative (

关键词： the Tarim Basin, chlorine isotope, ancient salt rock, ancient sylvinite deposit, deposit stage

Pb isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia,China

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Global Geology 2002年第1期7卷 54-61页

作者： ZHANG Hongying(Jilin University, Changchun 130026, P. R. China)LIANG Yibo(Hailun Normal School, Hailun 152300, P. R. China) Jilin University Changchun130026 P. R. China Hailun Normal School Hailun152300 P. R. China

There are two types of gold ore in Shibaqinghao gold deposit, a mylonite ore and a quartz - vein ore. Pb isotope compositions for mylonite ore are characterized by lower Pb isotope ratios ranging from 16.63 to 17.45 (206Pb/204Pb), 15.31 to15.48 (207Pb/204pb), 36.52 to 38.85 (208Pb/204Pb). They are scattered very close to a model curve of the mantle evolution. These ratios suggest that gold in the mylonite ore might be derived from the country rocks, which originated directly in the upper mantle. Pb isotope compositions for quartz - vein ore are characterized by higher Pb isotope ratios ranging from 18.23 to 19.74 (206Pb/204Pb), 15.69 to 15.89 (207Pb/204Pb), 38.64 to 40. 13 (208Pb/204Pb). They are scattered very close to a model curve of the upper crustal evolution. These facts indicate that the gold in the quartz - vein ore might be related to some granitic magma generated in the crust.

关键词： Pb isotope, Shibaqinghao gold ore deposit, Mylonite ore, Quartz vein ore

Reconstruction of summer temperature (June-August) at ***,China,from tree-ring stable carbon isotope values since AD 1890

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Science China Earth Sciences 2002年第12期45卷 1127-1136页

作者：刘禹马利民蔡秋芳安芷生刘卫国高玲瑜 State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China State Key Laboratory of Pollution and Resource Reuse of Tongji University Shanghai 200092 China

From stable carbon isotope analysis of tree-rings of Chinese pine (Pinus tabulaeformis) from Mt. Helan, China, we found that high-δ13C values were related to high mean temperatures from June to August (T 68), and Iow-δ13C values corresponded to low T 68. From these data, a transfer function has been used to reconstruct summer temperatures (T 68) for the Mt. Helan region. The explained variance of reconstruction is 34.9% (F=15.01, p<0.001). The time period containing the highest summer temperatures in northern China (late 1920-1930s) was confirmed by our reconstruction. The data indicate that there is a tele-connection between summer temperatures in Mt. Helan area and sea-surface-temperatures in the tropical Pacific. The extreme low temperature periods around the years of 1920 and 1947 for Mt. Helan region correspond well to the cold climate in the tropical Pacific. Along with other analyses, this suggests that climate variations in the Mt. Helan region are driven not only by local events, but also by the global climate. Significant periodicities appearing in the reconstruction are 2.56 and 2.63 years.

关键词： Mt. Helan, tree-ring stable carbon isotope, the summer temperature (T68) reconstruction.

Nitrogen isotope and content record of Mesozoic orogenic gold deposits surrounding the North China craton

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Science China Earth Sciences 2003年第3期46卷 231-245页

作者：毛景文张作衡王义天贾叶飞 Robert Kerrich Faculty of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Institute of Mineral Deposits Chinese Academy of Geological SciencesBeijing 100037China Department of Geological Sciences University of SaskatchewanSaskatoonSK S7N 5E2Canada

As an effective tracer, nitrogen isotopes have been used to determine the source of ore materials in recent years. In this study, the nitrogen isotopes and contents were measured on K-feldspar and sericite of gold deposits and some related granitic intrusions in Jiaodong, Xiao-qinling-Xiong’ershan, west Qinling, the west part of North Qilian and the Zhangjiakou-Xuanhua district around the North China craton (NCC). Although the gold deposits around the NCC are hosted in Precambrian metamorphic rocks, Phanerozoic sedimentary rocks, mafic volcanic rocks or granite, comparison of which with the nitrogen contents and isotope data of previous studies on mantle-derived rocks, granites, metamorphic rocks and gold deposits indicates that those deposits are closely related to granitic rocks. In addition, mantle-derived materials may have been involved in the ore-forming processes to a certain degree. This conclusion is consistent with the result of previous hydrogen, oxygen and carbon isotopic studies of those gold deposits.

关键词： nitrogen isotope, nitrogen content, gold deposit, margins of the North China craton.

The carbon isotope composition of C3 herbaceous plants in loess area of northern China

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Science China Earth Sciences 2003年第10期46卷 1069-1076页

作者：王国安韩家懋刘东生 College of Environmental Sciences Peking University Beijing 100871 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

13C of 367 C3 herbaceous plants was measured in loess area in northern China. Their δ13C values vary between ?21.7%. and ?30.0%., with a mean of ?26.7%.. In the center of Loess Plateau (semimoist area) with annual precipitation of 400–600 mm, the δ13 C values of C3 herbaceous plants range from ?24.4%. to ?28.5%., with a mean of ?27.5%.. In the west of Loess Plateau (semiarid and arid area) with annual precipitation less than 400 mm, they range between ?21.7%. and ?30.0%., with a mean of ?26.2%.. Annual precipitation is the main factor that makes δ13C values of C3 herbaceous plants in the west greater than those in the central Loess Plateau. The composition of δ13C in C3 plants increases with deceasing annual precipitation, and the mean change is ?49%./100 mm.

关键词： C3 herbaceous plants, carbon isotope, loess area, annual precipitation.

Fluid mixing as the mechanism of formation of the Dajing Cu-Sn-Ag-Pb-Zn ore deposit,Inner Mongolia ——Fluid inclusion and stable isotope evidence

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Science China Earth Sciences 2003年第7期46卷 652-663页

作者：刘伟李新俊谭骏 Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences

Dajing Cu-Sn-Ag-Pb-Zn ore deposit, in the Inner Mongolia Autonomous Region of China, is a fissure-filling hydrothermal ore deposit. The d D values of quartz-hosted inclusion water are centered at -100 — -130. The d 34S values of sulfide ore minerals and d 13C values of carbonate gangue minerals vary from 0.3 to 2.6 and from -2.9 to -7.0, respectively. Integrated isotopic data point to two major contributions to the mineralizing fluid that include a dominant meteoric-derived groundwater, and sulfur and carbon species from hypogene magma. Linear trends are exhibited on the gaseous H2O versus CO2 plot, and plots of CO, N2, CH4, and C2H6. It is shown by quantitative simulation that magma degassing cannot explain the linear trends. Hence, these linear trends are interpreted in terms of mixing of CO2-rich magmatic fluid with meteoric-derived groundwater. The groundwater circulated in Paleozoic sedimentary rocks and absorbed CO, N2, CH4, C2H6 and radiogenic Ar from organic matter. Cooling effects resulting from mixing have caused the precipitation of ore minerals.

关键词： fluid mixing, fluid inclusion, quadrupole mass spectrometer, stable isotope, Dajing ore deposit.

Carbon isotope characteristics,origin and distribution of the natural gases from the Tertiary salty lacustrine facies in the West Depression Region in the Qaidam Basin

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Science China Earth Sciences 2003年第7期46卷 694-707页

作者：张晓宝胡勇马立元孟自芳段毅周世新彭德华 State Key Laboratory of Gas Geochemistry Lanzhou Institute of Geology Chinese Academy of Sciences Research Institute of Petroleum Exploration and Development Qinghai Petroleum Company CNPC

The Tertiary in the West Depression Region of the Qaidam Basin has the typical inland salty lacustrine deposits in China. 34 natural gas samples were collected from 13 oil fields in the West Depression Region in the basin, the chemical compositions and carbon isotopes of methane, ethane, propane, and butane were measured. According to the carbon isotope characteristics of natural gases in combination with geochemical characteristics of the source rocks and crude oils, the natural gases can be divided into sapropelic associated gas, mixed organic matter-derived associated gas, coal-derived gas and mixed gas. The carbon isotope characteristics, origin and distribution of the natural gases are considered to be related with the types and distribution of organic inputs in lake environments with different salinities. The lake salinity can regionally forecast the distribution of the different genetic types of natural gas. Compared with the different genetic types of natural gas from other Chinese basins, the carbon isotopes of the heavy hydrocarbons of the natural gas from the Tertiary salt lacustrine facies in the Qaidam Basin are extremely heavier. Therefore, this should be considered when natural gases are genetically classified in the basin.

关键词： salt lacustrine, natural gas carbon isotope, genetic type, natural gas forecast, Qaidam Basin.

SHRIMP U-Pb zircon age,geochemistry and Nd isotope of the Guandaoshan pluton in SW Sichuan:Petrogenesis and tectonic significance

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Science China Earth Sciences 2003年第Z1期46卷 73-83页

作者：李献华李正祥周汉文刘颖梁细荣李武显 Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China Tectonics Special Research Centre School of Earth and Geographical Sciences The University of Western Australia Crawley WA 6009 Australia Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China

SHRIMP U-Pb zircon age, geochemical and Nd isotopic data are reported for the Neoproterozoic Guandaoshan pluton in the Yanbian region, SW Sichuan. This pluton is of typical I-type granite and emplaced at (857±13) Ma. Geochemical and Nd isotopic characters suggest that the pluton was generated by partial melting of pre-existing, young (late Mesoproterozoic to early Neoproterozoic) low-K tholeiitic protolith within an intraplate anorogenic setting. The Guandaoshan pluton probably records the earliest magmatism induced by the proposed ca. 860-750 Ma mantle superplume beneath the supercontinent Rodinia.

关键词： granitoids, U-Pb zircon age, geochemistry, Nd isotope, SW Sichuan, Neoproterozoic.

Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing

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Science China Earth Sciences 2004年第10期47卷 943-953页

作者： TIAN Jun WANG Pinxian CHENG Xinrong Laboratory of Marine Geology Tongji University Shanghai 200092 China Laboratory of Marine Geology Tongji University Shanghai 200092 China Laboratory of Marine Geology Tongji University Shanghai 200092 China

The foraminiferal δ 18O and δ 13C records for the past 5 Ma at ODP Site 1143 reveal the linear responses of the Plio-Pleistocene climatic changes in the southern South China Sea to orbital forcing at the obliquity and precession bands. The phase of the δ 18O variations with the orbital forcing is opposite to that of the δ 13C, which may be caused by the frequent El Ni?o events from the equatorial Pacific. The amplification of the Northern Hemisphere Ice Sheet at ?3.3 Ma probably affected the development of the 100-ka climatic cycles. Its further spreading may spur the 100-ka climatic cycle to become the dominant cycle in the late Pleistocene. The “Mid- Pleistocene Transition” event has localized influence on the isotopic variations in the southern South China Sea. The foraminiferal δ 13C records for the past 5 Ma at Site 1143 are highly coherent with the orbital forcing at the long eccentricity band, and lead the δ 18O records at the shorter eccentricity band, highlighting the importance of the carbon cycle in the global climate change.

关键词： southern South China Sea, ODP, oxygen and carbon isotope, orbital forcing.