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Sulfur and Oxygen Isotopes of Sulfate Extracted from Early Cambrian Phosphorite Nodules： Implications for Marine Redox Evolution in the Yangtze Platform

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Journal of Earth Science 2016年第2期27卷 170-179页

作者： Wenlang Qiao xianguo lang Yongbo Peng Kaiyuan Jiang Wu Chen Kangjun Huang Bing Shen Guizhou Geological Survey Guiyang Guizhou Province 550018 China Key Laboratory of Orogenic Belts and Crustal Evolution MOE & School of Earth and Space Sciences Peking University Beijing 100871 China Department of Geology and Geophysics Louisiana State University Baton Rouge LA 70803 USA

Phosphorite nodule beds are discovered in the black shale of basal Niutitang Formation throughout the Yangtze Platform in South China, recording an important phosphorite-generation event. Platform-wide phosphorite precipitation requires special oceanographic and geochemical conditions, thus the origin of the Niutitang phosphorite nodules may provide valuable information about the ocean chemistry in the Early Cambrian. In this study, we measured sulfur and oxygen isotopic compositions of sulfate extracted from phosphorite nodules collected from the basal Niutitang Formation. Phosphorite associated sulfate（PAS） is a trace amount of sulfate that incorporates into crystal lattice during phosphorite precipitation, accordingly PAS records the geochemical signals during phosphorite nodule formation. Sulfur isotopic composition of PAS（δ^（34）S_（PAS）） ranges from-1.16‰ to ＋24.48‰（mean=＋8.19‰, n=11）, and oxygen isotopic value（δ^（18）O_（PAS）） varies between-5.3‰ and ＋26.3‰（mean=＋7.0‰, n=8）. Most phosphorite nodules have low δ^（34）SPAS and low δ^（18）O_（PAS） values, suggesting PAS mainly derived from anaerobic oxidation of H_2S within suboxic sediment porewater. We propose that phosphate was delivered to the Yangtze Platform by a series of upwelling events, and was scavenged from seawater with the precipitation of FeOOH. The absorbed phosphate was released into suboxic porewater by the reduction of FeOOH at the oxic-suboxic redox boundary in sediments, and phosphorite nodule precipitated by the reaction of phosphate with Ca^（2＋） diffused from the overlying seawater. The platform-wide deposition of phosphorite nodules in the basal Niutitang Formation implies the bottom water might be suboxic or even oxic, at least sporadically, in Early Cambrian. We speculate that the intensified ocean circulation as evident with frequent occurrences of upwelling events might be the primary reason for the episodic oxidation of the Yangtze Platform in Early Cambrian.

关键词： phosphorite nodules Niutitang Formation phosphorite associated sulfate sulfurisotope oxygen isotope.

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Marine Carbon-Sulfur Biogeochemical Cycles during the Steptoean Positive Carbon Isotope Excursion(SPICE) in the Jiangnan Basin, South China

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Journal of Earth Science 2016年第2期27卷 242-254页

作者： Yang Peng Yongbo Peng xianguo lang Haoran Ma Kangjun Huang Fangbing Li Bing Shen Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space Science Peking University Beijing 100871 China Department of Geology & Geophysics Louisiana State University Baton Rouge LA 70803 USA

Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon（δ^（13）C） and organic carbon（δ^（13）C_（org）） isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate（CAS, δ^（34）S_（CAS）） and pyrite（δ^（34）S_（pyrite））, unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ^（13）C_（carb） of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ^（34）S_（CAS） and δ^（34）S_（pyrite） have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound（VOSC, such as methanethiol and dimethyl sulfide） formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of ^（32）S from continental margins to open oceans, elevating δ^（34）S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.

关键词： steptoean positive carbon isotope excursion sulfur isotope Qingxi Formation SouthChina volatile organic sulfur compound.

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Heterogeneous Mg isotopic composition of the early Carboniferous limestone: implications for carbonate as a seawater archive

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Acta Geochimica 2018年第1期37卷 1-18页

作者： Haoran Ma Yihe Xu Kangjun Huang Yuanlin Sun Shan Ke Yang Peng xianguo lang Zhen Yan Bing Shen Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Sciences Peking University State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

Carbonate precipitation and hydrothermal reaction are the two major processes that remove Mg from *** isotopes are significantly(up to 5%)fractionated during carbonate precipitation by preferential incorporation of ^(24)Mg,while hydrothermal reactions are associated with negligible Mg isotope fractionation by preferential sequestration of^( 26)***,the marine Mg cycle could be reflected by seawater Mg isotopic composition(δ^(26)Mg_(sw)),which might be recorded in marine ***,carbonates are both texturally and compositionally heterogeneous,and it is unclear which carbonate component is the most reliable for reconstructing δ^(26)Mg_(sw).In this study,we measured Mg isotopic compositions of limestone samples collected from the early Carboniferous Huangjin Formation in South *** on petrographic studies,four carbonate components were recognized:micrite,marine cement,brachiopod shell,and *** four components had distinct δ^(26)Mg:(1)micrite samples ranged from -2.86% to -2.97%;(2)pure marine cements varied from -3.40% to -3.54%,while impure cement samples containing small amount of Rugosa coral skeletons showed a wider range(-3.27% to-3.75%);(3)values for the mixture component were-3.17% and -3.49%;and (4)brachiopod shells ranged from -2.20% to -3.07%,with the thickened hinge area enriched in ^( 24)*** to having multiple carbonate sources,neither the micrite nor the mixture component could be used to reconstruct δ^(26)Mg_(sw).In addition,the marine cement was homogenous in Mg isotopes,but lacking the fractionation by inorganic carbonate precipitation that is prerequisite for the accurate determination of δ^(26)Mg_(sw).Furthermore,brachiopod shells had heterogeneous C and Mg isotopes,suggesting a significant vital effect during ***,the heterogeneous δ^(26)Mg of the Huangjin limestone makes it difficult to reconstruct δ^(26)Mg_(sw)using bulk carbonate/calcareous ***,δ^(26)Mg_(sw)was only slightly affected by

关键词： Seawater Mg isotopic composition Limestone Fossil Micrite Cement

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Cracking the superheavy pyrite enigma: possible roles of volatile organosulfur compound emission

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National Science Review 2021年第10期8卷 101-114页

作者： xianguo lang Zhouqiao Zhao Haoran Ma Kangjun Huang Songzhuo Li Chuanming Zhou Shuhai Xiao Yongbo Peng Yonggang Liu Wenbo Tang Bing Shen State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation and Institute of Sedimentary Geology Chengdu University of Technology Key Laboratory of Orogenic Belts and Crustal Evolution of the Ministry of Education and School of Earth and Space Science Peking University State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment Chinese Academy of Sciences School of Physics Peking University State Key Laboratory of Continental Dynamics Northwest University Shaanxi Key Laboratory of Early Life and Environments Department of Geology Northwest University Department of Geosciences Virginia Polytechnic Institute and State University International Center for Isotope Effect Research Nanjing University School of Earth Sciences and Engineering Nanjing University School of Mathematical and Statistical Sciences Arizona State University

The global deposition of superheavy pyrite(pyrite isotopically heavier than coeval seawater sulfate in the Neoproterozoic Era and particularly in the Cryogenian Period) defies explanation using the canonical marine sulfur cycle system. Here we report petrographic and sulfur isotopic data(δS) of superheavy pyrite from the Cryogenian Datangpo Formation(660–650 Ma) in South China. Our data indicate a syndepositional/early diagenetic origin of the Datangpo superheavy pyrite, withS-enriched HS supplied from sulfidic(HS rich) seawater. Instructed by a novel sulfur-cycling model, we propose that the emission ofS-depleted volatile organosulfur compounds(VOSC) that were generated via sulfide methylation may have contributed to the formation ofS-enriched sulfidic seawater and superheavy pyrite. The global emission of VOSC may be attributed to enhanced organic matter production after the Sturtian glaciation in the context of widespread sulfidic conditions. These findings demonstrate that VOSC cycling is an important component of the sulfur cycle in Proterozoic oceans.

关键词： sulfur isotope organosulfur compound sulfur cycle Cryogenian Datangpo Formation

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A Great late Ediacaran ice age

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National Science Review 2023年第8期10卷 105-118页

作者： Ruimin Wang Bing Shen xianguo lang Bin Wen Ross N. Mitchell Haoran Ma Zongjun Yin Yongbo Peng Yonggang Liu Chuanming Zhou Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education and School of Earth and Space SciencesPeking University 2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation and Institute of Sedimentary GeologyChengdu University of Technology 3. State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences School of Earth Sciences and Engineering Nanjing University State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment Chinese Academy of Sciences School of Physics Peking University

The emergence of the Ediacara biota soon after the Gaskiers glaciation ca. 580 million years ago(Ma)implies a possible glacial fuse for the evolution of animals. However, the timing of Ediacaran glaciation remains controversial because of poor age constraints on the ～30 Ediacaran glacial deposits known worldwide. In addition, paleomagnetic constraints and a lack of convincing Snowball-like cap carbonates indicate that Ediacaran glaciations likely did not occur at low latitudes. Thus, reconciling the global occurrences without global glaciation remains a paradox. Here, we report that the large amplitude, globally synchronous ca. 571–562 Ma Shuram carbon isotope excursion occurs below the Ediacaran Hankalchough glacial deposit in Tarim, confirming a post-Shuram glaciation. Leveraging paleomagnetic evidence for a～90° reorientation of all continents due to true polar wander, and a non-Snowball condition that rules out low-latitude glaciations, we use paleogeographic reconstructions to further constrain glacial ages. Our results depict a ‘Great Ediacaran Glaciation’ occurring diachronously but continuously from ca.580–560 Ma as different continents migrated through polar–temperate latitudes. The succession of radiation, turnover and extinction of the Ediacara biota strongly reflects glacial–deglacial dynamics.

关键词： carbonate carbon isotopes Shuram excursion inertial interchange true polar wander (IITPW) hankalchough glaciation Tarim Block

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华南埃迪卡拉纪晚期深水相氮循环过程重建

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地球科学 2024年第9期49卷 3212-3227页

作者：叶凯云赵坤童霞李松倬郎咸国成都理工大学沉积地质研究院四川成都610059 中国石油大庆油田有限责任公司成都勘探开发研究院四川成都610051

重建地质历史时期的古海洋氮循环过程有助于了解当时的海洋氧化还原状态,而目前埃迪卡拉纪晚期的海洋氮循环研究程度较低,因此对桂北泗里口和黔东南上地坪剖面开展了详细的全岩氮(δ15N)和有机碳同位素(δ13C_(org))研究.结果显示,泗里... 详细信息

重建地质历史时期的古海洋氮循环过程有助于了解当时的海洋氧化还原状态,而目前埃迪卡拉纪晚期的海洋氮循环研究程度较低,因此对桂北泗里口和黔东南上地坪剖面开展了详细的全岩氮(δ15N)和有机碳同位素(δ13C_(org))研究.结果显示,泗里口和上地坪剖面的δ15N平均值分别为(1.6±2.0)‰和(3.5±1.1)‰,总体上均表现为由老到新逐渐降低,两个剖面的δ13_(Corg)平均值分别为(-30.0±1.4)‰和(-30.6±1.4)‰.较高的δ15N值表明该时期为硝化‒反硝化作用相耦合的好氧氮循环,海洋中存在一个稳定的硝酸盐库.研究剖面δ15N值由老到新均表现为逐渐降低,可解释为底层缺氧水体的扩张,反硝化作用和厌氧氨氧化作用消耗了表层水体中大量的NO3‒,刺激了固氮作用.因此,埃迪卡拉纪末期深部缺氧水体的扩张可能加剧了~542 Ma埃迪卡拉生物群的灭绝.

关键词：氮同位素埃迪卡拉纪晚期深水相华南地球化学地层学.

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成冰纪全球冰期事件的环境效应研究进展

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沉积与特提斯地质 2023年第3期43卷 651-660页

作者：郎咸国陈家乐成都理工大学沉积地质研究院四川成都610059

成冰纪全球冰期是地球历史上最极端的冰室气候事件,冰川作用波及赤道区域,全球可能都遭受了冰封,海洋广泛缺氧,生物演化进程迟滞。然而,冰期结束之后,大气氧浓度迅速升高,海洋发生逐步氧化,大型带刺疑源类和真核多细胞藻类在埃迪卡拉纪... 详细信息

成冰纪全球冰期是地球历史上最极端的冰室气候事件,冰川作用波及赤道区域,全球可能都遭受了冰封,海洋广泛缺氧,生物演化进程迟滞。然而,冰期结束之后,大气氧浓度迅速升高,海洋发生逐步氧化,大型带刺疑源类和真核多细胞藻类在埃迪卡拉纪开始繁盛,出现最早的动物,地表生物圈发生了翻天覆地的变化。显然,成冰纪全球冰期事件是地球系统演化的重要转折。认识冰期的环境效应是认识埃迪卡拉纪生物演化的关键,也是打开地表宜居环境演化的钥匙。本文总结了近年来成冰纪全球冰期的气候假说、冰期沉积特征、海洋氧化还原条件及冰期后的大气与海洋环境剧变等方面的研究进展,简要分析了全球冰期研究中存在的问题,并对该领域未来研究提出了展望与建议。

关键词：雪球地球南沱组生产力氧化新元古代

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镁同位素示踪碳酸盐岩沉积—成岩过程——对恢复深时海水镁同位素组成的启示

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沉积学报 2021年第6期39卷 1546-1564页

作者：夏攀甯濛文华国郎咸国成都理工大学沉积地质研究院成都610059 中石油碳酸盐岩储层重点实验室成都理工大学研究分室成都610059 油气藏地质及开发工程国家重点实验室(成都理工大学) 成都610059 北京大学地球与空间科学学院北京100871

镁(Mg)作为主要的造岩元素及生物营养元素,是连接大陆、海洋和地球内部循环的重要纽带。碳酸盐岩作为Mg的主要储库,是全球Mg循环的重要组成环节,利用Mg同位素示踪碳酸盐岩沉积—成岩过程是有效反演深时海水Mg同位素组成(δ^(26)Mg_(海... 详细信息

镁(Mg)作为主要的造岩元素及生物营养元素,是连接大陆、海洋和地球内部循环的重要纽带。碳酸盐岩作为Mg的主要储库,是全球Mg循环的重要组成环节,利用Mg同位素示踪碳酸盐岩沉积—成岩过程是有效反演深时海水Mg同位素组成(δ^(26)Mg_(海水))、恢复全球Mg循环的基本前提。近二十年来,Mg同位素在示踪碳酸盐岩沉积—成岩过程研究中取得了较大进展:1)不同类型碳酸盐矿物形成过程中的Mg同位素分馏及其影响因素的研究得到完善;2)建立了Mg同位素地球化学模型,对不同白云石化过程进行半定量—定量模拟;3)初步探索了利用Mg同位素反演早期成岩流体体系的方法。以上研究进展为利用碳酸盐岩恢复δ26Mg_(海水)奠定了理论基础,在选择有效的碳酸盐岩载体恢复δ26Mg_(海水)时,需充分考虑碳酸盐岩的沉积—成岩过程及其对Mg同位素组成的影响,并适当结合地球化学模型,消除沉积—成岩因素的影响,进而恢复δ26Mg_(海水)。

关键词： Mg同位素海相碳酸盐岩沉积—成岩过程白云石化过程海水Mg同位素组成

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斯图特雪球地球存在持续的海洋碳循环

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沉积学报 2024年第1期42卷 29-38页

作者：满玲祝圣贤邓宾李玉坤郎咸国成都理工大学沉积地质研究院成都610059 广西地质调查院南宁530023

[目的]斯图特雪球地球事件是地质历史时期最极端的冰室气候。在冰期过程中,冰盖分布范围达到低纬度甚至古赤道区域,海洋被完全冰冻。目前,斯图特雪球地球过程中的古海洋化学研究相对薄弱,且生物地球化学循环机制尚不明确。[方法]对桂北... 详细信息

[目的]斯图特雪球地球事件是地质历史时期最极端的冰室气候。在冰期过程中,冰盖分布范围达到低纬度甚至古赤道区域,海洋被完全冰冻。目前,斯图特雪球地球过程中的古海洋化学研究相对薄弱,且生物地球化学循环机制尚不明确。[方法]对桂北地区成冰系富禄组开展了详细的野外调查和碳氧同位素及元素地球化学研究。[结果]桂北地区成冰系富禄组形成于斯图特雪球地球过程中,岩性主要为一套碎屑岩,并发育多套碳酸盐岩夹层。地球化学分析显示这些碳酸盐岩具有相对稳定的碳同位素值(平均值为-3.5‰),并与伴生的有机碳同位素呈现不耦合关系。[结论]富禄组碳酸盐岩的碳同位素值明显高于地幔碳同位素值(-6‰),指示斯图特雪球地球过程中的海洋初级生产力并未完全停止,只是表现为较低的水平。海洋热液系统提供的磷可能是维持冰期海洋初级生产力的主要原因。

关键词：碳同位素碳酸盐岩富禄组新元古代

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川东北地区晚埃迪卡拉纪灯影期海水氧化还原环境重建

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沉积学报 2023年第1期41卷 183-195页

作者：赵坤满玲贺然李松倬祝圣贤郎咸国成都理工大学沉积地质研究院成都610059 中国石油西南油气田公司勘探开发研究院成都610051

晚埃迪卡拉纪全球海洋发生了大面积的缺氧,海洋化学结构呈现明显的非均质性,直接影响了埃迪卡拉型生物的演化与分布。四川盆地发育完整的晚埃迪卡拉系地层,以灯影组巨厚层碳酸盐岩沉积为代表。但是对于该套巨厚层碳酸盐岩沉积时的古海... 详细信息

晚埃迪卡拉纪全球海洋发生了大面积的缺氧,海洋化学结构呈现明显的非均质性,直接影响了埃迪卡拉型生物的演化与分布。四川盆地发育完整的晚埃迪卡拉系地层,以灯影组巨厚层碳酸盐岩沉积为代表。但是对于该套巨厚层碳酸盐岩沉积时的古海水氧化还原性质备受争议。为了解决这一问题,对川东北地区鹿池剖面的灯影组地层开展了系统的沉积学和稀土元素地球化学分析。该地区灯影组的岩石类型主要为泥微晶白云岩、黏连白云岩、叠层/层纹白云岩,以及溶蚀白云岩,沉积环境为开阔碳酸盐岩台地相。地球化学数据结果显示灯影组碳酸盐岩普遍具有较低的稀土总量(∑REE+Y值为0.4~3.3μg/g)、较低的Mn/Sr值(0.2~2.8)和较高的Fe含量(55.9~1772.6μg/g)。灯影组的REE+Y配分曲线(经页岩标准化)可划分为四个阶段,且Ce异常指示该地区经历了弱氧化到弱还原再到缺氧状态,表明埃迪卡拉纪晚期海洋浅部水体也发生了缺氧现象。

关键词：灯影组白云岩海洋缺氧稀土元素四川盆地

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