| 古代碳酸盐岩台地自生泥质组分成因及意义 |
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| 引用本文： | 苏成鹏,李飞,谭秀成,王小芳,龚峤林,李明隆,芦飞凡,唐浩,邓嘉婷,李红.古代碳酸盐岩台地自生泥质组分成因及意义[J].沉积学报,2021,39(3):550-570. |
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| 作者姓名： | 苏成鹏 李飞 谭秀成 王小芳 龚峤林 李明隆 芦飞凡 唐浩 邓嘉婷 李红 |
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| 作者单位： | 1.油气藏地质及开发工程国家重点实验室，西南石油大学，成都 610500 |
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| 基金项目： | 国家自然科学基金41872119, 41502115四川省科技计划项目20YYJC1185 |
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| 摘 要： | 台地泥质组分沉积记录了源—汇过程和环境演化等沉积学领域信息，可作为古气候和古环境重建的重要载体。然而，利用沉积物中的泥质组分进行古气候和古环境恢复时仍存在相当大的复杂性和局限性。鉴于此，笔者以上寺剖面中二叠统茅口组为例，通过研究该层位富泥质组分灰岩—泥灰岩韵律的宏微观形貌学和矿物学特征，发现其泥质组分主要由成岩黏土矿物海泡石构成，其次为少量滑石和蒙脱石。基于前人认识，进一步运用电子探针和激光原位元素地球化学分析手段，综合认为海泡石中镁元素来源于继承海水的孔隙水以及亚稳定矿物的转化释放，硅元素可能来源于上扬子台地的同沉积期断裂热液。此外，滑石主要形成于海泡石埋藏过程中的成岩转化，蒙脱石可能也具有类似成因，但不排除有少量蒙脱石来源于火山物质的海底改造。结合区域资料，华南中二叠统浅水碳酸盐台地上广泛发育自生成因（早期成岩作用和埋藏成岩作用）泥质组分。因此，在利用泥质组分来恢复古环境的时候，需要谨慎识别其成因，这将有利于提高沉积旋回识别和环境解释的准确性；另一方面，对自生成因泥质组分进行专门研究，在成岩过程以及成岩地球化学信号识别上也具有参考价值。
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| 关 键 词： | 中二叠统 灰岩—泥灰岩韵律 自生黏土矿物 海泡石 差异成岩作用 |
| 收稿时间： | 2020-06-24 |
Origin and Significance of Authigenic Argillaceous Components on the Ancient Carbonate Platform: A case study from the Maokou Formation of the Middle Permian at the Shangsi section,Guangyuan |
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| SU ChengPeng,LI Fei,TAN XiuCheng,WANG XiaoFang,GONG QiaoLin,LI MingLong,LU FeiFan,TANG Hao,DENG JiaTing,LI Hong.Origin and Significance of Authigenic Argillaceous Components on the Ancient Carbonate Platform: A case study from the Maokou Formation of the Middle Permian at the Shangsi section,Guangyuan[J].Acta Sedimentologica Sinica,2021,39(3):550-570. |
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| Authors: | SU ChengPeng LI Fei TAN XiuCheng WANG XiaoFang GONG QiaoLin LI MingLong LU FeiFan TANG Hao DENG JiaTing LI Hong |
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| Abstract: | Terrigenous fine-grained components developed on the platform settings can record massive amounts of information on source-to-sink processes and palaeoenvironmental evolutions， which can be used as an archive for the reconstruction of ancient climate and provenance. Yet， authigenic clays are visible in carbonate rocks， and their formation mechanism and diagenetic effect deserve more attention. Here， the authigenic marl components developed in carbonate rocks of the Maokou Formation （Middle Permian） at the Shangsi section have been studied in order to understand their origin and formation processes. The argillaceous component is mainly composed of the diagenetic clay mineral sepiolite， and a small amount of talc and montmorillonite. The source of Mg in sepiolite is speculated to be derived from the pore water inherited from seawater and the release of metastable carbonate minerals （e.g.， high-Mg calcites）， while Si may be sourced from the supply of hydrothermal fluid diffused from an active fault on the upper Yangtze platform. In addition， talc and montmorillonite minerals are likely derived from the alteration of sepiolite during the burial phase based on petrological and mineralogical evidence. Even so， a small amount of montmorillonite may originate from volcanic materials. In sum， authigenic argillaceous components are very common in the strata of the Maokou Formation， which are widely mixed with terrigenous fine-grained fractions in sedimentary records. These diagenetic clays would potentially affect the reliability of palaeoclimatic and palaeoenvironmental analyses if their contamination effects cannot be eliminated. In addition， the study of authigenic clays has potential significance in the understanding of diagenetic process and the identification of diagenetic geochemical signatures. |
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