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

来源 :Chinese Science Bulletin | 被引量 : 0次 | 上传用户:guosl1987
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
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 deep seawater. Successive analyzes 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 to other variation of 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 an 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 The organic productivity and burial rate of organic carbon once reached a quite high level during the Doushantuo stage. However, the state of environment has been unstable after the global glaciation. The global climate and environment possibly 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 deep seawater.
其他文献
种草发展养殖,养殖必须种草,这是我国新世纪的养殖业发展的必由之路,是加快转化、实现高效饲养羊、牛的重大举措。根据以往和近年来各地种草的实践效果,现提供适于我国农区
在生产过程中,气力送砂系统的湿法除尘装置产生大量泥浆,需及时处理。过去由于没有专门处理设备,只好人工清理,效率很低,且又脏又累。有时来不及处理,造成泥浆从沉淀池内漫
论述了西德煤矿关于 CH_4及 CO 的测定任务与依据的概要,以及研制的2~3种连续的或准备连续的固定式测定装置。利用集中红外线分析原理操作的装置为最好。Essen-Kray 煤矿研究
抚顺煤炭科学研究所的广大工人阶级和革命的知识分子在驻所工、军宣和革委会的领导下,遵照伟大领袖毛主席“自力更生”的教导,自行设计和制造了 MGB—1型矿用安全火花型光电
基于几年来的许多现场经验,作者意见在设计浮选厂粗选回路时,采用长列浮选机比以每列的处理量相应少的多数短列浮选机,可获得较高的处理能力和回收率,并得到较好的生产效率
地方个别领导干部给进行舆论监督的人穿“玻璃小鞋”,对向新闻媒体如实去信反映当地管理问题的人实行“高压政策”,这样的事可谓屡见不鲜。群众写信的“手腕”在权力报复的
黄委会学术委员会于1992年11月6~7日在郑州对委属各单位的报奖科技成果进行了评审,共评出1992年度黄委会科技进步奖16项,其中一等奖2项(①水质数据计算机管理系统;②孟加拉国
Learning English as a foreign language is a step-by-step process, during which Chinese students will inevitably make some errors. It is important for teachers t
一家媒体要想在众多竞争者中脱颖而出,必须要有自己独特的个性。媒体的个性,是媒体工作者从自身的实际出发创造出符合媒体本身特点的管理观念、管理方式、品牌形象。一家媒
Channel parameters estimation in an orthogonal frequency division multiple access(OFDMA)systemfor the receiver station is a multi-dimensional(MD)optimization p