Tertiary Gravity Flow Deposits in Jinggu-Zhenyuan Region, Southwestern Yunnan, and Their Geological Significance
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摘要: 本文通过详细的沉积学研究，讨论了滇西南景谷—镇沅地区第三纪重力流的沉积特征，包括碎屑流、颗粒流和浊流三种沉积类型。它们的发育直接受印度板块与欧亚板块碰撞及其后陆内变形的控制，是区域构造事件的响应。Abstract: The Tertiary gravity flow deposits in the Jingg u-Zhenyuan region, southwestern Yunnan, can be divided into three types: debris flow, grain flow and turbidity current. Debris flow deposits are mainly composed of conglomerates, which are matrix supported and poorly sorted. Their grain-size distribution frequency curves are characterized by having only one major and some secondary peaks. Grain flow deposits are also mainly composed of conglomerates, which are identified by their matrix lacking features. Clasts in these deposits were cemented by ironoxides and clay minerals, as thin film around them. Their grain-size distribution frequency curves show multimodal distribution without major peak. Turbidity current deposits are mainly composed of sandstone, siltstone and mudstone, which are characterized by their Bouma sequence. Their grain-size cumulative proba bility curves and C-M diagram reflect features of low-density flow. Development of the gravity flow in the region, asresponse to regional tectonic evolution, was controlled by collisional processes of Indian continent with Eurasian continent and post-collisional intracon-tinental deformation.
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Key words:
- gravity flow /
- debris flow /
- grain flow /
- turbidity current
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