ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    碳酸盐岩再沉积中冰碛杂岩与重力流沉积的关系探讨

    Carbonate Rocks Resedimentation: The Relationship Between Tillite and Gravity-Flow Deposits

    • 摘要: 碳酸盐岩再沉积作用在地质记录中常有发育,但受控冰期作用的碳酸盐岩再沉积事件记录相对较少,碳酸盐台地及斜坡背景下的冰期再沉积过程研究更为薄弱。笔者通过对比分析埃迪卡拉系凤台组冰碛杂岩与重力流沉积物的沉积结构、岩相特征及组合关系,总结两类沉积体的判识标志,探讨二者在成因与演化上的关联性。研究认为,冰川驱动的机械剥蚀与搬运既可形成冰碛杂岩,也为重力流提供物质来源;而冰期后期海平面上升或构造活动则诱发台地边缘失稳,触发滑塌、碎屑流与浊流等重力流过程,形成再沉积的碳酸盐岩沉积物。两者在部分沉积特征上存在相似性,但在动力机制和沉积环境方面存在明显差异。在区域沉积演化过程中,冰碛杂岩可作为重力流沉积的“前置触发”与“物源供给”,二者皆是构成冰期碳酸盐岩再沉积体系的重要组成部分。加强对受风化碳酸盐岩的剥蚀、搬运及沉积成岩过程探究,完善碳酸盐岩再沉积源汇系统,对古环境重建和油气资源分布评价具有重要意义。

       

      Abstract: Carbonate resedimentation is commonly recorded in the geological record; however, glaciation-controlled carbonate resedimentation events are relatively scarce, and research on glacial resedimentation processes within carbonate platform and slope settings remains poorly understood. Through comparative analysis of the sedimentary structures, lithofacies characteristics, and assemblage relationships of tillite and gravity-flow deposits in the Ediacaran Fengtai Formation, this study summarizes the diagnostic criteria for these two deposit types and explores their genetic and evolutionary interconnections. It is proposed that glacially driven mechanical erosion and transport not only generate tillite but also supply material for gravity flows. Post-glacial sea-level rise or tectonic activity can induce destabilization of platform margins, triggering gravity-flow processes including slumping, debris flows, and turbidity currents, and thereby forming redeposited carbonate sediments. Although the two deposit types exhibit similarities in certain depositional characteristics, they differ markedly in dynamic mechanisms and depositional environments. Within the context of regional depositional evolution, tillite may act as both a precursor trigger and a sediment source for gravity-flow deposits; together, they constitute integral components of the glacial carbonate resedimentation system. Strengthened investigation into the erosion, transport, and depositional-diagenetic processes of weathered carbonate rocks, and the consequent refinement of the carbonate source-to-sink system, are of significant importance for paleoenvironmental reconstruction and the evaluation of hydrocarbon resource distribution.

       

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