| 黔中地区震旦系洋水组地球化学特征及其对古海洋环境的指示* |
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| 引用本文： | 王泽鹏,吴文明,刘建中,杜远生,张亚冠,付勇,陈国勇,李磊,谭代卫,王大福,潘启权,汪小勇,黄毅,万大学.黔中地区震旦系洋水组地球化学特征及其对古海洋环境的指示*[J].古地理学报,2021,23(3):610-624. |
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| 作者姓名： | 王泽鹏 吴文明 刘建中 杜远生 张亚冠 付勇 陈国勇 李磊 谭代卫 王大福 潘启权 汪小勇 黄毅 万大学 |
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| 作者单位： | 1.贵州省地质矿产勘查开发局105地质大队,贵州贵阳 550018;2.贵州省地质矿产勘查开发局,贵州贵阳 550004;3.中国地质大学(武汉)生物地质与环境地质国家重点实验室,地球科学学院,湖北武汉 430074;4.中国地质大学(武汉)资源学院,湖北武汉 430074;5.自然资源部基岩区矿产资源勘查工程技术创新中心,贵州贵阳 550081;6.贵州大学资源与环境工程学院,贵州贵阳 550025 |
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| 基金项目： | *国家自然科学基金项目(编号: U1812405)、贵州省第二批整装勘查项目和第三批国家级整装勘查项目、中国地质调查局项目(编号: 12120114016501)和(编号: 0747-1661SITCN131)、贵州省地质矿产勘查开发局地质科研项目(黔地矿办发[2016]10号和11号)联合资助 |
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| 摘 要： | 为重建黔中地区震旦纪陡山沱期古海洋环境,选取小河磷矿(XH)、息烽磷矿(XF)含磷岩系剖面,通过系统采样及岩矿鉴定、扫描电镜、微量元素和稀土元素分析,揭示古海洋环境对磷块岩沉积的影响作用。结果表明,磷矿成矿受黔中古陆长期剥蚀夷平形成的无障壁海岸海滩环境控制。陡山沱期洋水组磷块岩Sr/Ba值一般大于1,均值分别为1.90(XH)和0.95(XF),而澄江组沉积物Sr/Ba值均小于1,均值分别为0.11(XH)和0.18(XF),说明沉积环境由澄江期的湖泊相转变为陡山沱期的海相。小河剖面V/Cr和Ni/Co均值分别为1.77和2.17,息烽剖面V/Cr和Ni/Co均值分别为1.26和2.83,均位于弱氧化—氧化区间。息烽磷矿磷块岩δCe为0.75~0.95,均值0.85,小河磷矿磷块岩δCe为0.74~1.09,均值0.88,Ce负异常由底部至顶部逐渐增大,显示沉积环境由次氧化—氧化的转变。这种氧化转变不仅造成了浅水富磷海岸大洋生产力的提升,进一步促使与生物作用相关的磷块岩沉积,同时造成的生命演化也改变了大洋含氧结构,因此成磷环境的氧化转变是对新元古代氧化事件与生命演化的响应。
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| 关 键 词： | 黔中地区 陡山沱期 磷矿 洋水组 地球化学 古海洋环境 |
| 收稿时间： | 2020-07-11 |
Geochemical characteristics of the Sinian Yangshui Formation and their implications for palaeoceanographic environments in central Guizhou Province |
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| Wang Ze-Peng,Wu Wen-Ming,Liu Jian-Zhong,Du Yuan-Sheng,Zhang Ya-Guan,Fu Yong,Chen Guo-Yong,Li Lei,Tan Dai-Wei,Wang Da-Fu,Pan Qi-Quan,Wang Xiao-Yong,Huang Yi,Wan Da-Xue.Geochemical characteristics of the Sinian Yangshui Formation and their implications for palaeoceanographic environments in central Guizhou Province[J].Journal of Palaeogeography,2021,23(3):610-624. |
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| Authors: | Wang Ze-Peng Wu Wen-Ming Liu Jian-Zhong Du Yuan-Sheng Zhang Ya-Guan Fu Yong Chen Guo-Yong Li Lei Tan Dai-Wei Wang Da-Fu Pan Qi-Quan Wang Xiao-Yong Huang Yi Wan Da-Xue |
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| Abstract: | To reconstruct the palaeoceanographic environments during the Ediacaran Doushantuo period,this study focused on the phosphatic sequences of the Xiaohe(XH)and Xifeng(XF)phosphorite orefield to reveal the interaction between deposition of phosphorites and their sedimentary environments,by means of identification of rock and minerals,SEM,trace and rare earth elements analyses on phosphatic samples. Research results show that deposition of phosphorite was controlled by palaeo-morphology of shallow shoals around the Qianzhong Oldland. The ratio of Sr/Ba in phosphatic samples in Yangshui Formation is commonly larger than 1,and the average value is 1.90(XH)and 0.95(XF),respectively. The Sr/Ba ratio of samples in the Chenjiang Formation is less than 1 with average values of 0.11(XH)and 0.18(XF). The different results of the Sr/Ba ratio suggest transformation from lacustrine environments in the Chengjiang period to marine environments. The ratios of V/Cr and Ni/Co in phosphatic deposits in the Xiaohe Yansgshui Formation are 1.77 and 2.17,respectively,and 1.26 and 2.83 in the Xifeng section,collectively indicating suboxic to oxic environments. The values of δCe in the Xifeng phosphorites are limited between 0.75 and 0.95 with a mean value of 0.85,and those in the Xiaohe phosphorites are 0.74 to 1.09(mean value of 0.88). Increase of negative Ce anomalies from the bottom to the top of the Yangshui Formation shows that sedimentary environments transferred from suboxic to oxic. The change of paleo-ocean geochemical values suggests the increase of the ocean productivity in coastal environments,stimulating deposition of biological action induced phosphorite,and the life evolution also changed the oxygen content and distribution in ocean. Therefore,the transformation of phosphogenesis environments is a positive response to the Neoproterozoic Oxygenation Event and life evolution. |
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| Keywords: | central Guizhou Province Doushantuoian phosphorite Yangshui Formation geochemistry ancient marine environment |
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