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    赣西北修水、武宁地区中新生代“红盆”地质时代和沉积相研究

    Geological times and sedimenrtary facies of the Mesozoic and Cenozoic “red basins” in the Xiushui and Wuning regions, northwestern Jiangxi

    • 摘要: 通过新发现的古生物资料分析,确定了赣西北修水、武宁地区的武宁、三都及马坳盆地的地层时代。对3个盆地的沉积相进行了详细的划分和描述,查明其为冲积扇沉积类型;划分出22个岩相,归属于泥石流、泥流、颗粒流、水道(包括主水道和分枝水道2个次级类型)、片流、筛积和洪泛7个沉积类型。重力流沉积分布在扇根或主要沉积旋回的底部,其类型的差别与邻近物源区的岩性有关;分枝水道、片流及筛积主要分布在扇中,交错层理及砾石叠瓦状构造发育,主要呈现牵引流特征;扇缘主要为洪泛沉积夹少量决口扇成因的砂砾岩透镜体,钙结壳发育,反映了一种干旱强蒸发的古气候环境。

       

      Abstract: The stratigraphic ages have been determinated on the basis of the new palaeontological data for the Wuning, Sandu and Ma'ao Basins in the Xiushui and Wuning regions in northwestern Jiangxi. Twenty-two lithofacies assigned to seven sedimentary types have also been distinguished, including debris flow deposits, mud flow deposits, grain flow deposits, stream-channel (including main channel and distributary channel) deposits, sheet flow deposits, sieve deposits and flood-plain deposits in the basins outlined above. The gravity-flow (deposits) appear in the proximal fan and/or at the base of major depositional cycles. The differences of their sedimentary types may be caused by the variations in lithology in the contiguous provenances. The distributary channel deposits, sheet flow deposits and sieve deposits are concentrated in the mid-fan, where the cross-(beddings), brecciated structures and tractional current marks are extremely conspicuous. The fan fringes are (occupied) by the flood-plain deposits intercalated with minor amount of sandstone and conglomerate lenses of the crevasse-splay origin. The widespread caliche indicates a highly arid palaeoclimate.

       

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