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Variations of sulfur and carbon isotopes in seawater during the Doushantuo stage in late Neoproterozoic

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chinese Science Bulletin 2003年第13期48卷 1375-1380页

作者： zhang tonggang, chu xuelei, zhang qirui, feng lianjun & HUO Weiguo Key Lab of Mineral Resources Exploration and Research, institute of geology and geophysics, chinese academy of sciences, beijing 100029, china Key Lab of Mineral Resources Exploration and Research Institute of Geology and Geophysics Chinese Academy of Sciences China

Successive analyses of sulfur and carbon isotopic compositions of carbonates strata in the Doushantuo Formation in the Yangtze area were accomplished through a method of extracting trace sulfate from carbonates. Sulfur and carbon isotopic compositions of coeval seawater were estimated from the samples that show the least diagenetic alteration. A high-resolution age curve of sulfur isotopes in seawater sulfates was obtained in the Doushantuo stage, which reflects the trend of variation in seawater sulfur isotopes after the Neoproterozoic snowball Earth event. Similar characteristics of variation in carbon isotopes were observed in the coeval carbonates. A large positive d 34S excursion over +20?occurs in ancient seawater sulfates in the early Doushantuo stage. Simultaneously, the d 13C values in ancient seawater carbonates exhibit a positive excursion up to 10. The maximum d 34S and d 13C values are +46.4 and +6.9? respectively. In the middle Doushantuo stage, the range of variation in d 34S values of seawater is relatively narrow, but d 13C values are quite high. Then, d 34S values of seawater become oscillating, and the same occurs in d 13C values. Negative excursions in d 34S and d 13C values occur simultaneously at the end of the Doushantuo stage, and the minimum d 34S and d 13C values dropped down to -10.1 and -5.7? respectively. The characteristics of variations in the sulfur and carbon isotopes of ancient seawater imply strong changes in oceanic environment that became beneficial to inhabitation and propagation of organism. The organic productivity and burial rate of organic carbon once reached a quite high level during the Doushantuo stage. However, the state of environment became unstable after the global glaciation. The global climate and environment possibly were fluctuating and reiterating. The negative excursions in d 34S and d 13C values occurring at the end of the Doushantuo stage may represent a global event, which might be related to oxidation of dee

关键词：硫碳同位素分馏新元古代成岩作用

Discussion on the Neoproterozoic glaciations in the South china Block and their related paleolatitudes

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chinese Science Bulletin 2009年第10期54卷 1797-1800页

作者： zhang qirui chu xuelei feng lianjun State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029China

The Kaigas, Sturtian, Marinoan, and Gaskiers glaciations are widely recognized in Neoproterozoic. However, in the South china Block only the Jiangkou (Sturtian) and Nantuo (Marinoan) are symbolized by sedimentary records. The Kaigas, recorded by isotopic and chemical proxies, exhibited likely the nature of cold paleoclimate with local mountain glaciation. The correlation of the Doushantuo Formation with the Gaskiers is indicated by the carbon isotope excursion and the dated age from the interval, however the South china Block was then under non-glacial weather. With no paleomagnetic data, the position of the South china Block during the Sturtian glaciation cannot be determined. The paleolatitudes of the South china Block during the Kaigas and Nantuo glaciations are intermediate, even though the Nantuo was once rendered erratically deduced equatorial. In fact, the paleolatitudes of the South china Block during the Neoproterozoic glaciations are all likely at about 30°―40°.

关键词：冰期气候新元古代中国碳同位素古地磁数据沉积记录寒冷气候时间间隔

Carbon isotopic variations of Proterozoic carbonates in Jixian,Tianjin,china

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Carbon isotopic variations of Proterozoic carbonates in Jixi...

中国科学院地质与地球物理研究所2004学术年会

作者： chu xuelei~(1,2),zhang tonggang~(1,2),zhang qirui~1,feng lianjun~(1,2) & zhang fusong~1 1.institute of geology and geophysics,chinese academy of sciences,beijing 100029,china 2.Key Laboratory for Mineral Resources Research,chinese academy of sciences,beijing 100029,china

Along the Proterozoic stratigraphic sections of Jixian,Tianjin,theδC values of carbonates are mostly negative in the Changchengian(Changcheng System),varying approximately within a range of(0±1)‰in the Jixianian(Jixian System),and have commonly positive values of(2+2)‰in the Qingbaikouan(Qingbaikou System).From chuanlinggou Formation to Dahongyu Formation,*** ca.1700 Ma to 1600 Ma,theδC values of carbonates increase from about -3‰to 0‰,but oscillate with large excursion in Dahongyu *** large excursions occur in the Jixianian,one in Yangzhuang Formation and the other in the third submember of Wumishan Formation *** integrated and continuous records of carbon isotope reflect secular variations ofδC value in ancient seawater from ca.1700 Ma to ca.800 *** increase and subsequent oscillation of seawaterδC value occurring from the ages of ca.1700 to ca.1600 Ma and1300 Ma may signify two correlative global tectonic events.

关键词： Proterozoic Jixian carbon isotope chemostratigraphy secular variation global tectonic event

Sulfur and carbon isotopic variations in Neoproterozoic sedimentary rocks from southern china

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Progress in Natural Science:Materials International 2003年第11期 75-80页

作者： chu xuelei 1,2*, zhang qirui 1, zhang tonggang 1,2 and feng lianjun 1,2(1. institute of geology and geophysics, chinese academy of sciences, beijing 100029, china 2. Key Laboratory for Mineral Resources Research, chinese academy of sciences, beijing 100029, china) institute of geology and geophysics，chinese academy of sciences，beijing 100029，china Key Laboratory for Mineral Resources Research，chinese academy of sciences，beijing 100029，china institute of geology and geophysics，chinese academy of sciences，beijing 100029，china

A new set of δ 34S sulfide, δ 34S sulfate and δ 13C carbonate values has been reported from Neoproterozoic sedimentary rocks in southern china. The interglacial black shales of the Datangpo Fm. display higher δ 34S sulfide values with >+20‰ average, but the postglacial black shales from the Doushantuo Fm. show negative δ 34S sulfide values. However, the Jinjiadong Fm., the same post-glaciation as the Doushantuo Fm., has positive δ 34S sulfide values, implying that the δ 34S value of sedimentary sulfides would be controlled by lithofacies and paleogeographic environments. The δ 34S sulfate values relative to δ 13C carbonate were obtained by extraction of trace sulfate from the successive carbonate sequences in the Yangtze Gorges sections. A preliminary interpretation suggests that the oceanic environment may fluctuate dramatically at the post-glacial Doushantuo stage and, then, recover its stability at the Dengying stage on the basis of the high resolution δ 34S and δ 13C curves of seawater.

关键词： Neoproterozoic southern china sulfur isotopes carbon isotopes seawater secular variations.

Sulfur and carbon isotopic variations in Neoproterozoic sedimentary rocks from southern china

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Sulfur and carbon isotopic variations in Neoproterozoic sedi...

中国科学院地质与地球物理研究所2003学术年会

作者： chu xuelei~(1,2**),zhang qirui~1,zhang tonggang~(1,2) and feng lianjun~(1,2) (1.institute of geology and geophysics,chinese academy of sciences,beijing 100029,china 2.Key Laboratory for Mineral Resources Research,chinese academy of sciences,beijing 100029,china)

A new set of δS,δSand δCvalues has been reported from Neoproterozoic sedimentary rocks in southern *** interglacial black shales of the Datangpo *** higherδSvalues with>+20‰average,but the postglacial black shales from the Doushantuo *** negativeδ***,the Jinjiadong Fm.,the same post-glaciation as the Doushantuo Fm.,has positiveδSvalues,implying that theδS value of sedimentary sulfides would be controlled by lithofacies and paleogeographic ***δSvalues relative toδCwere obtained by extraction of trace sulfate from the successive carbonate sequences in the Yangtze Gorges sections.A preliminary interpretation suggests that the oceanic environment may fluctuate dramatically at the post-glacial Doushantuo stage and,then,recover its stability at the Dengying stage on the basis of the high resolutionδS andδC curves of seawater.

关键词： Neoproterozoic southern china sulfur isotopes carbon isotopes seawater secular variations

Variations of sulfur and carbon isotopes in seawater during the Doushantuo stage in late Neoproterozoic

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Variations of sulfur and carbon isotopes in seawater during ...

中国科学院地质与地球物理研究所2003学术年会

Successive analyses of sulfur and carbon isotopic compositions of carbonates strata in the Doushantuo Formation in the Yangtze area were accomplished through a method of extracting trace sulfate from *** and carbon isotopic compositions of coeval seawater were estimated from the samples that show the least diagenetic alteration.A high-resolution age curve of sulfur isotopes in seawater sulfates was obtained in the Doushantuo stage, which reflects the trend of variation in seawater sulfur isotopes after the Neoproterozoic snowball Earth *** characteristics of variation in carbon isotopes were observed in the coeval carbonates.A large positiveδS excursion over +20‰occurs in ancient seawater sulfates in the early Doushantuo ***,theδC values in ancient seawater carbonates exhibit a positive excursion up to 10‰. The maximumδS andδC values are +46.4‰and +6.9‰, *** the middle Doushantuo stage,the range of variation inδS values of seawater is relatively narrow,butδC values are quite ***,δS values of seawater become oscillating,and the same occurs inδC values. Negative excursions inδS andδC values occur simultaneously at the end of the Doushantuo stage,and the minimumδS andδC values dropped down to-10.1‰and -5.7‰,*** characteristics of variations in the sulfur and carbon isotopes of ancient seawater imply strong changes in oceanic environment that became beneficial to inhabitation and propagation of *** organic productivity and burial rate of organic carbon once reached a quite high level during the Doushantuo ***,the state of environment became unstable after the global glacistion. The global climate and environment possibly were fluctuating and *** negative excursions inδS andδC values occurring at the end of the Doushantuo stage may represent a global event,which might be related to oxidation of deep seawater.

关键词： Doushantuo stage sulfur isotope carbon isotope snowball Earth bacterial sulfate reduction isotopic fractionation

Genesis of Silica-phosphatic Nodules with Small Shelly Fossils Preserved in the Lowermost Cambrian of South china

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Acta Geologica Sinica(English Edition) 2022年第4期96卷 1294-1307页

作者： QIU Hao feng lianjun chu xuelei LI Luoyang zhang Xingliang LI Jinhua Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdaoShandong 266100China State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environments Department of GeologyNorthwest UniversityXi’an 710069China

Silica-phosphatic nodules are abundant in black shales of the Yanjiahe Formation in the Three Gorges Area of South china,which is correlated to the Fortunian Stage,Terreneuvian Series,Cambrian *** nodules are rich in small shelly fossils and hence attract the attention of numerous paleontologists and sedimentary ***,the genesis of the nodules and the preservation of the small shelly fossils are poorly *** we analyze morphological,structural,mineralogical and chemical features of the nodules in multiscale using a combination of micro-X-ray fluorescence spectroscopy,X-ray diffraction,scanning electron microscopy and confocal laser Raman *** reveal that nodules are concentric in chemical and mineralogical compositions,comprising a silica-phosphatic core encrusted sequentially by a phosphatic zone,a siliceous zone and a very thin pyrite outer *** black shales hosting the nodules demonstrate a laminated texture of alternating clayey and silty laminae,which were respectively deposited in sulfidic/less sulfidic,high/low production,intense/weak chemical weathering *** phosphogenesis of the nodules resulted in the phosphatization of small shelly fossils,which prevented the fossils from being dissolved during diagenesis,whereas the silica encrustation sealed the fossils within the nodules and thus protected the fossils from alteration by deep burial and surface weathering.

关键词： silica-phosphatic nodule small shelly fossils Yanjiahe Formation taphonomy Cambrian

New evidence of deposition under cold climate for the Xieshuihe Formation of the Nanhua System in northwestern Hunan,china

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New evidence of deposition under cold climate for the Xieshu...

中国科学院地质与地球物理研究所2004学术年会

作者： feng lianjun~(1,2),chu xuelei~(1,2),zhang qirui~1, zhang tonggang~(1,2),LI He~1 & JIANG Neng~(1,2) 1.institute of geology and geophysics.chinese academy of sciences. beijing 100029.china: 2.Key Laboratory for Mineral Resources Research.chinese academy of sciences.beijing 100029.china

Yangjiaping section is located in Hupingshan Town,Shimen County,Hunan *** section has been intensively studied since ***,The paleoclimate during the deposition of the Xieshuihe Formation remains *** on chemical analysis of sedimentary clastic rocks of the unit,the resulting CIA(the chemical index of alteration) values of the Xieshuihe Formation are similar to those of the overlying Gucheng Formation(also called the Dongshanfeng Formation).It indicates that the sedimentary rocks of the Xieshuihe Formation and Gucheng Formation underwent the similar degrees of chemical weathering before ***,the Xieshuihe Formation was also likely to be deposited under a cold climatic condition,which probably belongs to a part of the record of glaciations.

关键词： Neoproterozoic Yangjiaping section Xieshuihe Formation Gucheng(Chang’an) glacial epoch chemical weathering paleoclimate

On-line measurements ofδ15N in biological fluids by a modified continuous-flow elemental analyzer with an isotope-ratio mass spectrometer

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On-line measurements ofδ15N in biological fluids by a modif...

中国科学院地质与地球物理研究所2008学术年会

作者： Xu Wang~(1*),lianjun feng~2,fusong zhang~2 and Zhongli Ding~1 1 Key Laboratory of Cenozoic geology and Environment,institute of geology and geophysics,chinese academy of sciences, RO.Box 9825,beijing 100029,china 2 Lab for Stable Isotope Geochemistry,institute of geology and geophysics,chinese academy of sciences,RO.Box 9825, beijing 100029,china

A modified continuous-flow elemental analyzer coupled to an isotope-ratio mass spectrometer (modified EA-IRMS) was tested for on-lineδN measurement on urea solution and biological fluids (***).The elemental analyzer configuration was adapted by adding a U-shaped cold trap and an X-pattem four-way valve for on-line trapping/venting of water from the liquid *** indicate that theδN ratios show little variation(standard deviation(SD) = 0.05‰) with a sample size above the equivalent N yield of 0.2 mg urea(0.092 mg N) when the mass spectrometer conditions were carefully *** contrast,a significant logarithmic decrease inδN with sample size was observed but this can be offset by applying a linearity correction or blank correction when the sample size is between equivalent N yields of 0.05 and 0.2 mg *** blank correctedδN ratios give an overall precision of .16‰whereas the average precision forδN corrected using combined linearity and shift correction is 0.05‰.The relatively large variation in blank correctedδN values may be attributed to the variability of the blankδN in the ***,the blank correction should be carefully performed in routine *** a result,the linearity range of a modified EA-IRMS can be extended to a minimum sample size of 0.023 mg *** addition, the reproducibility of the new system is good,as indicated by the precision(<0.2‰) for a set of standards and *** data show that fluids containing nitrogen can be successfully analyzed in the modified EA-IRMS.

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