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Lower Carboniferous carbon isotope stratigraphy in South china: Implications for the Late Paleozoic glaciation

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Science china Earth Sciences 2011年第1期54卷 84-92页

作者： QIE WenKun ZHANG XiongHua DU YuanSheng ZHANG Yang State key laboratory of Geological Process and Mineral Resources China University of Geosciences Wuhan 430074 China key laboratory of biogeology and environmental geology of ministry of education China University of Geosciences Wuhan 430074 China

Studies on carbon isotopes of bulk carbonates from Longan and Baping sections of Lower Carboniferous in Guangxi of china show that the stable carbon isotope compositions in carbonate rocks of the isolated platform and deep slope facies were resistant to the influence of early meteoric diagenesis and late burial diagenesis. Three major positive carbon isotope excursions have been recognized in Lower Carboniferous in South china. The first major positive δ3C shift of 4.19‰ occurred in the middle part of Siphonodella isosticha-upper Siphonodella crenulata zone （Tournaisian）; the second with an amplitude of 4.65‰ occurred near the Tournaisian/Visean boundary; and the third of 2.23‰ in the lower part of Gnathodus bollandensis zone. The three positive shifts of δ3C can be correlated with global carbon isotope excursions and are consistent with the fall in global sea level, indicating that abundant organic carbon burial, lowering of atmospheric CO2, and glaciation may have occurred during these time intervals.

关键词： Carboniferous glaciation carbon isotope Guangxi South china

Investigation of Stable C and Cl Isotope Effects of Trichloroethene and Tetrachloroethylene during Evaporation at Different Temperatures

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Journal of Earth Science 2014年第4期25卷 735-740页

作者： Tingting Yu Yiqun Gan Aiguo Zhou Kai Yu Yunde Liu School of environmental Studies China University of Geosciences State key laboratory of biogeology and environmental geology China University of Geosciences

There are variations of reported isotope enrichment factors of chlorinated organic contaminants in evaporation processes. Trichloroethene （TCE） and tetrachloroethylene （PCE） were chosen to study carbon and chlorine isotope effects during evaporation at different temperatures. Equilibrium vapor-liquid carbon and chlorine isotope effects experiments were also conducted. In the equilibrium liquid-vapor system, the 13C was enriched but 37Cl was depleted in the vapor phase, being consistent with previous results. For evaporation average carbon isotope enrichment factor εc were ＋0.28‰± 0.01‰ for TCE and ＋0.56‰±0.09‰ for PCE at temperature from 20 to 26 ℃. Meanwhile, average chlorine isotope enrichment factor εCl were -1.33‰±0.21‰ for TCE and -1.00‰±0.00‰ for PCE. The results indicate that during evaporation the equilibrium isotope effect attenuates the magnitude of carbon isotope fractionation whereas enhances the chlorine isotope effect. Isotope fractionation during evaporation is determined by both equilibrium and kinetic factors. Chlorine isotope fractionation is influenced by the evaporation rate which is linked to temperature. When using stable isotope to inves- tigate the behavior of chlorinated organic contaminants in groundwater with slow biodegradation rate, the isotope fractionation resulted from evaporation should be taken into consideration. Furthermore, the environment conditions such as temperature are also factors to be considered.

关键词： chlorine isotope carbon isotope evaporation isotope fractionation chlorinated organic contaminant groundwater.

Permian–Triassic Climatic and environmental Extremes and Biotic Response (IGCP 630:2014–2018):Goals and Achievements

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Acta Geologica Sinica(English Edition) 2019年第3期93卷 780-782页

作者： CHEN Zhongqiang GUO Zhen State key laboratory of biogeology & environmental geology China University of Geosciences

IGCP 630,with its full title of"Permian-Triassic(P-Tr)climatic and environmental extremes and biotic response",is an International Geoscience Program project sponsored by the United Nation educational,Scientific&Cultural Organization(UNESCO)and International Union of Geological Sciences(IUGS).This project was approved in 2014 and ended in 2018,and has applied for one-year extension in *** 630 consists of 150 geoscientists across multidisciplinary geosciences from 27 countries around the world.

关键词： Permian-Triassic Climatic environmental Extremes Biotic Response

U-Pb geochronology of hydrothermal zircon from the Mesoproterozoic Gaoyuzhuang Formation on the northern margin of the North china Block and its geological implications

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Science china Earth Sciences 2011年第11期54卷 1675-1685页

作者： GUO Hua DU YuanSheng YANG JiangHai GUO Liang key laboratory of biogeology and environmental geology of ministry of education China University of Geosciences Wuhan 430074 China State key laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China

This paper reports LA-ICP-MS zircon U-Pb ages and REE compositions on detrital zircons （Type 1） and hydrothermal zircons （Type 2） from low-metasedimentary rocks in the Mesoproterozoic Gaoyuzhuang Formation, Pingquan area, Hebei Province that provide important constraints on the tectonic evolution along the northern margin of the North china Block. The detrital zircons are characterized by an oscillatory magmatic core, surrounded by a narrow structureless rim in CL images. They yield 2~7pb/2~tpb ages ranging from 1703 to 2543 Ma with two age peaks at 2473 and 1794 Ma, which is consistent with the Neoarchean and Paleoproterozoic tectono-thermal events recorded in the NCB basement, indicating that the source of the detritus was locally derived. By contrast, the hydrothermal ones are euhedral, sector zoning or internally structureless. They have relatively higher U and Th contents and Th/U ratios （U=139-2918 ppm, Th=35-1327 ppm, Th/U （average） =0.78 vs. U=15-1044 ppm, Th=8-341 ppm, Th/U （average） =0.57 for detrital zircons）. Moreover, they are also enriched in REEs relative to detrital zircons and show a lower positive Ce anomaly （ZREE = 659-2418 ppm vs. 231-611 ppm for detrital zircon; Ce/Ce＊=2-13 vs. 33-174 for detrital zircons）, similar to known hydrothermal zircons derived from many locations. These characteristics, combined with our field petrographic observations, indicate that the hydrothermal zircons possibly formed from a low temperature aqueous fluid. Twelve concordant or near-concordant analyses on hydrothermal zircons yield weighted mean 206pb/238U ages of 325-327 Ma, which provide unambiguous evidence that the northern NCB underwent late Paleozoic low temperature hydrothermal modification. This timing of this hydrothermal event is compatible with that of the late Paleozoic magmatic and metamorphic-deformational events occurred on the northern margin of the NCB, it appears likely that the hydrothermal activity resulted from southward subduction of the Paleo-

关键词： hydrothermal zircon detrital zircon zircon geochronology late Paleozoic North china Block Central Asian Orogenicbelt

Devonian Frasnian-Famennian transitional event deposits of Guangxi, South china and their possible tsunami origin

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Science china Earth Sciences 2008年第11期51卷 1570-1580页

作者： DU YuanSheng GONG YiMing ZENG XiongWei HUANG HongWei YANG JiangHai ZHANG Zhe HUANG ZhiQiang State key laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China key laboratory of biogeology and environmental geology of ministry of education China University of GeosciencesWuhan 430074China

A suite of event deposits, isochronous and interrelated in origin, occurs widely near the Frasnian- Famennian boundary in Guangxi, South china. It is mainly distributed in the facies areas of the platform-margin slope and inter-platform rift-trough. The rudstone or calcirudite occur in the Liujing section of Hengxian and Luoxiu and Baqi sections of Xiangzhou in the facies area of platform-margin slope. The turbidites are observed in the sections of Yangdi and Baisha of Guilin, Du'an of Debao, Nandong and Sanli of Wuxuan, Xiangtian, Ma'anshan of Xiangzhou, Nayi of Chongzuo, Yunpan of Shanglin in the facies area of inter-platform rift-trough. The massive homogenites occur in sections of Mangchang, Luofu and Road from Nandan to Tian'e and Ma'anshan etc in the facies area of inter-platform rift-trough. Herein event deposits can be correlated in stratohorizon to the turbidite in the bottom of the Lower triangularis Zone in Hony railroad cut of Belgium, Devils Gate of Nevada, USA, Atrous of Morocco, South Urals and Fore-Kolyma of northeastern Siberia of Russia, and erosional discontinuities and brecciation in the Frasnian-Famennian boundary in South Polish-Moravian shelf. The event deposits could be caused by a violent tsunami related to bolide impacts into ocean.

关键词： Devonian Frasnian-Famennian mass extinction South china tsunami event deposits

A Technique for Carbon and Chlorine Isotope Analyses of Chlorinated Aliphatic Hydrocarbons in Groundwater

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Journal of Earth Science 2013年第2期24卷 274-281页

作者：甘义群余婷婷周爱国刘运德刘存富 School of environmental Studies China University of Geosciences State key laboratory of biogeology and environmental geology China University of Geosciences

Chlorinated aliphatic hydrocarbons （CAHs）, significant contaminants in groundwater, can be characterized by stable isotopic compositions of carbon and chlorine. Previously published methods were of low analytical sensitivity or not ideal for natural samples with low concentrations of CAHs. This method is reported here to carry out simultaneously carbon and chlorine isotope analyses for mieromolar concentrations of dissolved CAHs. It was executed by extracting and converting CAHs to carbon dioxide and methyl chloride （CH3CI）. Specially, a continuous-flow interface GasBench Ⅱ was used to extract CH3CI for online chlorine isotope analysis. As a result, it greatly enhances the efficiency for isotope analysis by eliminating procedures for offline CH3CI preparation and separation. Sample size requirement was reduced to approximately 11 pmol chlorine. The standard deviation of δ^＋3C and δ^37CI for both TCE solvents and water samples was better than 0.30‰ and 0.20%0 （1σ）, *** and chlorine isotope analyses can be used as an important tool to study the sources of organic contaminants in groundwater and their behaviors in the aquifers. The method is applicable to manufacturers＇ products as well as a sample from a polluted site in principle, which will be validated in our field studies.

关键词： chlorine isotope carbon isotope chlorinated aliphatic hydrocarbon (CAH) groundwater organic contamination.

Lower Triassic and Induan-Olenekian Boundary in Chaohu,Anhui Province,South china

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Acta Geologica Sinica(English Edition) 2011年第2期85卷 399-407页

作者： TONG Jinnan ZHAO Laishi key laboratory of biogeology and environmental geology of ministry of education China University of Geosciences Wuhan 430074 China State key laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China

Since the West Pingdingshan Section in Chaohu was proposed as the candidate of the Global Stratotype Section and Point of the Induan-Olenekian boundary in 2003, the Lower Triassic of Chaohu has been extensively studied. Based on the studies on the Lower Triassic of Chaohu, （1） a continuous conodont zonation is established, which has become an important reference for Lower Triassic stratigraphic correlation over the world; （2） the First Appearance Datum of conodont Neospathodus waageni was suggested and has been basically accepted as the primary marker to define the InduanOienekian boundary; （3） a characteristic Lower Triassic excursion of carbon isotopes was brought to light and has been proven to be not only an excellent index for the stratigraphic correlation but also a unique indication for the perturbation of ecological environments in the aftermath of the end-Permian mass extinction; （4） a magnetostratigraphic sequence is constituted with a certain biostratigraphic control in the low-latitude region and it presents an important correlation to the Boreal sequence; （5） a cyclostratigraphic study provides an alternative method to constrain the age of the chronostratigraphic units; and （6） a scheme of the Olenekian subdivision is recently suggested to define the boundary between the Smithian and Spathian Substages. In addition, Chaohu is also the type locality of the Chaohuan Stage, the upper stage of the Lower Triassic in the china Chronostratigraphic ***, the Lower Triassic of Chaohu is not only a classic sequence in South china, but also a key reference sequence to the investigation of the corresponding stratigraphy and geological events over the world. The recent achievements are viewed here for an overall understanding of the sequence. Then the current situation of the Induan-Olenekian and Smithian-Spathian boundaries is discussed to provide a reference for later works.

关键词： Lower Triassic Induan-Olenekian boundary Smithian-Spathian boundary Global Stratotype Section and Point Chaohu china

Sedimentary geochemistry and provenance of the Lower and Middle Devonian Laojunshan Formation,the North Qilian Orogenic Belt

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Science china Earth Sciences 2010年第3期53卷 356-367页

作者： XU YaJun DU YuanSheng YANG JiangHai HUANG Hu key laboratory of biogeology and environmental geology of china education ministry China University of GeosciencesWuhan 430074China State key laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

The Laojunshan Formation is a suite of molasse formed during the rapid uplift of the North Qilian Orogenic Belt (NQOB). Forty-one samples of sandstone have been collected from the Sunan and Minle sections in the western sector and the Gulang and Jingyuan sections in the eastern sector of the NQOB belt. Geochemical analyses of those samples indicated: 1) The MgO+Fe2O3T and Al2O3/SiO2 values are higher, and K2O/Na2O ratios are lower in the western sector than those in the eastern sector. 2) All of them are depleted in Nb and Ta elements. The samples from the western sector are depleted in Rb element and enriched with Sc, Co, Ni, V, and Cr elements in the Upper Crust-normalized patterns. However, those from the eastern sector are depleted in Sr without enrichments of Sc, Co, Ni, V, and Cr. 3) All of the samples display a right-inclined REE pattern af- ter Chondrite-normalized REE pattern. But LaN/YbN and Eu/Eu* ratios of the samples from the western sector are lower than those of the samples from the eastern sector. These geochemical characteristics suggest the prominent input of mafic clast with minor granitic rocks into the Sunan area, felsic clast into the Gulang and Jingyuan area, and both mafic and felsic clast into the Minle area. The angular shapes of gravels imply that these ill-sorted sediments were deposited near their sources without recy- cling. Geochemical features above also demonstrated that no major chemical weathering occurred for the western provenance, but deposits in the eastern sector resulted from low or middle degree chemical weathering. Evidences combining tectonic discriminations and comparisons with potential provenances revealed that sediments in the Sunan area were derived mainly from the North Qilian Continental arc, whereas sediments in the Minle, Gulang, and Jingyuan areas were derived not only from the North Qilian Continental arc but also from the basement of the Middle Qilian block. Integrated with the characteristics of development of

关键词： North Qilian Orogenic Belt (NQOB) Laojunshan Formation sedimentary geochemistry provenance orogeny

Lower Triassic Smithian-Spathian Boundary at West Pingdingshan Section in Chaohu,Anhui Province

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Science china Earth Sciences 2011年第3期54卷 372-379页

作者： LIANG Dan TONG JinNan ZHAO LaiShi key laboratory of biogeology and environmental geology of the ministry of education (china university of geosciences) Wuhan 430074 China State key laboratory of Geological Processes and Mineral Resources (china university of geosciences) Wuhan 430074 China

The West Pingdingshan Section in Chaohu, Anhui Province, has been extensively studied in recent years and become one of the classic Lower Triassic sequences well-clarified in multiple stratigraphies. Also it is an important section that defines the Smithian-Spathian (S-S) boundary within the Olenekian Stage. The S-S boundary strata at the section are restudied in high-resolution conodont biostratigraphy and carbon isotopes. The refined S-S boundary defined by the FAD of conodont Neospathodus pingdingshanensis is at 30 cm above the base of Bed 52, corresponding to a rapid diversification of conodonts. A sharp positive shift of δ13Ccarb curve co-occurs at the S-S boundary and it can be used as a key reference to define the boundary. The defined S-S boundary position and carbon isotopes curve can be well correlated globally.

关键词： Early Triassic Smithian-Spathian boundary conodont carbon isotopes Chaohu Anhui