| 川西南盐津地区志留系龙马溪组页岩地球化学特征及地质意义* |
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| 引用本文： | 何佳伟,谢渊,侯明才,刘建清,何利,芦云飞.川西南盐津地区志留系龙马溪组页岩地球化学特征及地质意义*[J].古地理学报,2021,23(6):1174-1191. |
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| 作者姓名： | 何佳伟 谢渊 侯明才 刘建清 何利 芦云飞 |
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| 作者单位： | 1.成都理工大学沉积地质研究院,四川成都 610059;2.中国地质调查局成都中心,四川成都 610081 |
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| 基金项目： | *中国地质调查局项目(编号: 12120114071401,121201010000150005)资助。 |
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| 摘 要： |
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| 关 键 词： | 川西南 盐津地区 龙马溪组 稀土元素 物源分析 构造背景 |
| 收稿时间： | 2020-12-21 |
Geochemical characteristics and geological significance of the Silurian Longmaxi Formation shale in Yanjin area,southwestern Sichuan Basin |
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| He Jia-Wei,Xie Yuan,Hou Ming-Cai,Liu Jian-Qing,He Li,Lu Yun-Fei.Geochemical characteristics and geological significance of the Silurian Longmaxi Formation shale in Yanjin area,southwestern Sichuan Basin[J].Journal of Palaeogeography,2021,23(6):1174-1191. |
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| Authors: | He Jia-Wei Xie Yuan Hou Ming-Cai Liu Jian-Qing He Li Lu Yun-Fei |
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| Institution: | 1.Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;2.Chengdu Center,China Geological Survey,Chengdu 610081,China |
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| Abstract: | In order to find out the element geochemical characteristics of Silurian Longmaxi Formation shale in Yanjin area,southwestern Sichuan Basin,as well as the material source and structural background of shale formation,the petromineralogy and geochemistry of 19 shale samples from Niuzhai section of Yanjin area were tested and analyzed. Combined with the previous research results and adjacent areas,the rare earth elements were mainly applied to discuss the sedimentary environment, the accumulation rate,material source and tectonic setting of the Longmaxi Formation shale in the study area. The results show that the mineral composition of the Longmaxi Formation in Niuzhai section of Yanjin is mainly quartz,carbonate minerals and clay minerals. The mineral triangle diagram shows that the Longmaxi Formation shale is mainly a combination of clay shale and mixed shale. The normalized partition pattern of rare earth elements is characterized by Ce deficit and weak Eu enrichment. The δCe values,Ni/Co and V/Cr values of the samples indicate that the paleo-water depth increases suddenly in the early stage and becomes shallow gradually in the later stage. Oxygen content gradually changes from anoxic reduction state in the early stage to weak oxidation state in the later stage. LaN/YbN values show that the shale deposition rate increases firstly and then decreases under the influence of sea level and terrigenous debris input. Provenance analysis shows that the source rocks area are mainly felsic igneous rocks and intermediate-acid geological bodies of granitoids. The La-Th-Sc diagram and tectonic setting characteristics show that the main tectonic setting of the source rocks is passive continental margin. Combined with previous studies and tectonic setting,it is inferred that the main source of the Longmaxi Formation shale is formed in the Passive continental margin of hypoxia,and the provenance is mainly from the Kang-Dian ancient land to the west of the study area,followed by the Central Guizhou uplift. |
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| Keywords: | southwestern Sichuan Basin Yanjin area Longmaxi Formation REE provenance analysis tectonic setting |
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