Paleo-sedimentary environment in relation to enrichment of organic matter of Early Cambrian black rocks of Niutitang Formation from Xiangxi area China
Paleo-sedimentary environment in relation to enrichment of organic matter of Early Cambrian black rocks of Niutitang Formation from Xiangxi area China
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湘西地区早寒武世牛蹄塘组黑色岩古沉积环境与有机质富集关系
DOI：
10.1016/j.marpetgeo.2019.104057
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发表时间：
2020-02
影响因子：
4.2
通讯作者：
Lawali Garba Chamssidini
中科院分区：
文献类型：
--
作者：
Rizwan Sarwar Awan;Chenglin Liu;Hongwei Gong;Chao Dun;Chao Tong;Lawali Garba Chamssidini
早寒武世富有机质黑色岩广泛分布于中国南方。本研究探讨了古沉积环境与有机质富集的关系。根据TOC资料，将牛蹄塘组划分为上、中、下三段。牛蹄塘组下部（1.55 wt %）和上部（1.35 wt %）的总有机碳量明显小于中部（8.0 wt %），分别反映了海平面的初始海侵阶段和回归阶段。两段中部（龙壁嘴和三岔）TOC含量均较高，提示海平面海侵阶段强烈，生物生产力较高。不同组分的干酪根类型指数（KTI）表明，该黑色岩系有机质以ⅰ型为主，ⅱ型有机质含量较少。此外，这些黑色岩石沉积在弱至中等限制的水文条件下。在这些黑色岩石中还观察到非均质矿物组成，包括石英、粘土、石膏、黄铁矿、重晶石、白云石和斜长石。中段石英含量相对高于上段，下段与TOC呈较强的正相关关系，说明中段沉积时石英的主要来源为生物石英。早寒武纪由于扬子与华夏板块之间的伸展作用，富含铀、钒、钼、锌、钡等的热液流体从地壳深处经伸展残余裂缝和裂缝进入大洋盆地，并因上升流现象进入陆架区。这些富含营养的深海地壳流体促进了浮游生物和其他海洋生物的进化和繁殖；同时，它提高了生物生产力。此外，它还造成了海底缺氧，这有利于沉积岩中有机质的保存。早寒武世牛蹄塘组黑色岩系有机质富集的主要因素分别是水文限制、热液活动和古氧化还原条件。
Early Cambrian organic-rich black rocks are extensively distributed in the southern China. In this study, we have discussed the relation of paleo-sedimentary environments with enrichment of organic matter. Based on TOC data, we divided the Niutitang Formation into three parts (Upper, Middle, and Lower). The amount of total organic carbon in the Lower (1.55 wt %) and the Upper part (1.35 wt %) of Niutitang Formation is significantly smaller than the Middle part (8.0 wt %) which suggest initial transgression, and regression stages of the sea level respectively. The Middle part from both sections (Longbizui and Sancha) contains higher TOC content, which is a clue of intense transgression stage of sea level with high bio-productivity. Kerogen type index (KTI) using different macerals specify the organic matter in these black rock series is mainly type-I with a minor amount of type-II1. Moreover, these black rocks were deposited in weak to moderately restricted hydrographic conditions. The heterogenic mineral composition was also observed in these black rocks, including quartz, clay, gypsum, pyrite, barite, dolomite, and plagioclase. Quartz content in the Middle part is relatively higher than the Upper, and the Lower part displays a strong positive relation with TOC which suggests the main source of quartz during deposition of the Middle part was biogenic quartz. During Early Cambrian period due to extension between the Yangtze and the Cathaysian plate, the hydrothermal fluids rich in uranium, vanadium, molybdenum, zinc, barium, etc. from the deeper part of the earth crust and entered the ocean basin through extensional remnant fissures and cracks, and due to upwelling phenomena entered to the shelf area. These nutrient-rich deep crustal fluids at the surface of the sea enhanced the evolution and breeding of planktons and other marine life; meanwhile, it upsurges the bio-productivity. Additionally, it creates bottom water hypoxia, which is favourable for the preservation of organic matter in the sedimentary rocks. The main factors responsible for the enrichment of organic matter in these Early Cambrian black rock series of Niutitang Formation were a hydrographic restriction, hydrothermal activities, and paleo-redox conditions, respectively.
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影响因子：
3.5
作者：
G. Demaison;G. T. Moore
通讯作者：
G. Demaison;G. T. Moore
DOI：
--
发表时间：
2004
期刊：
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影响因子：
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作者：
Sun Xing-li
通讯作者：
Sun Xing-li
DOI：
--
发表时间：
2003
期刊：
Geological Review
影响因子：
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作者：
Wang Darui
通讯作者：
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影响因子：
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作者：
Liu Qingyou;Tao Lei;Zhu Haiyan;Lei Zhengdong;Jiang Shu;John D.McLennan
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DOI：
10.1016/j.palaeo.2018.05.009
发表时间：
2018-09
期刊：
Palaeogeography, Palaeoclimatology, Palaeoecology
影响因子：
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