浙西常山蒲塘口剖面上奥陶统沉积相特征  

CHARACTERISTICS OF THE UPPER ORDOVICIAN LITHOFACIES IN THE PUTANGKOU SECTION, CHANGSHAN, WESTERN ZHEJIANG PROVINCE, SOUTH CHINA

作　　者：李文杰[1,2,3,4] 张元动 陈吉涛[1,3] 袁文伟[1] LI Wen-jie;ZHANG Yuan-dongl,;CHEN Ji-tao;and YUAN Wen-wei(Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;University of Chinese Academy of Sciences,Beijing 100049;CAS Key Laboratory of Economic Stratigraphy and Palaeogeography,Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;Academician Studio,Changshan National Geopark,Changshan 324200)

机构地区：[1]中国科学院南京地质古生物研究所和生物演化与环境卓越中心,江苏南京210008 [2]中国科学院大学,北京100049 [3]中国科学院资源地层学与古地理学重点实验室中国科学院南京地质古生物研究所和生物演化与环境卓越中心,江苏南京210008 [4]浙江省常山国家地质公园院士工作站,浙江常山324200

出　　处：《地层学杂志》2018年第4期393-407,共15页Journal of Stratigraphy

基　　金：中国科学院(XDB26010203;XDB10010100);国家自然科学基金(Nos.41772005;41521061);国家重大专项(2017ZX05036-001-004)联合资助;IGCP653项目"奥陶纪生物大辐射的启动机制"的阶段成果

摘　　要：浙江常山蒲塘口剖面由下至上出露上奥陶统砚瓦山组、黄泥岗组、三衢山组和长坞组,发育斜坡相碳酸盐岩和碎屑岩沉积,凯迪阶中含碎屑流沉积和以滑塌构造为主的软沉积物变形构造。砚瓦山组发育多期斜坡上部常见的中—远源碎屑流沉积、底流作用形成的含纹理条带状灰岩以及以钙质细砂岩为主的水下河道充填,出现大量原位软沉积物变形构造,包括火焰构造、小型泄水构造、沉积物挤入构造和塑性变形褶皱。黄泥岗组和三衢山组以含滑塌构造的深水相泥质灰岩为主,水体较砚瓦山组有所加深,至少有三期滑塌构造层。综合分析沉积岩相、软沉积物变形机制、大地构造背景,认为海底地形的坡度变陡和相对较高的沉积速率可能是砚瓦山组中大量软沉积物变形构造的触发机制,并且对其瘤状灰岩的形成也有一定的贡献。黄泥岗组、三衢山组中的滑塌构造可能与当时华夏古陆快速向北扩张、古地形逐渐变陡及地震作用有关。Late Ordovician carbonate and clastic deposits section near Changshan County, western Zhejiang, which of slope facies are well-exposed in the Putangkou are characterized by development of multiple epi sodes of large-scale slump structures formed in late Katian. In this study, we described the lithology and structures of the section layer by layer, and systematically collected series of samples for sedimentary analysis. Several beds of intermedium to distal debris flow deposits, laminated ribbon limestone and channel-fill calcareous fine sandstone are recorded near the base of the Putangkou section, mainly in the Yenwashan Formation. These features indicate a geological setting on the upper slope. The Huangnekang and Sanqushan formations are characterized by deep water argillaceous limestone with at least three episodes of slump structures, suggesting a deeper water condition than Yenwashan Formation. Additionally, we recorded abundant autochthonous soft sediment deformation structures （SSDS） in the Yenwashan Formation, including small-scale flame structures, water escape structures, sediment injection structures and folds. At least 3 episodes of slumps have been re- corded in the Huangnekang and Sanqushan formations. The characteristics of sedimentary lithofacies and SSDS, and the contemporary timing of the Kuangsian Orogeny, suggest that the sedimentation rate in the Yenwashan Formation was relatively high, which may account for the generation of the SSDS and the prevailing nodular limestone in the Yenwashan Formation. The large-scale slumps recorded in the Huangnekang and Sanqushan formations may have been triggered by an increasingly steepening slope ahead of the northward expansion of the Cathaysian Land and/or more frequent earthquakes related to the Kwangsian orogeny.

关 键 词：岩石地层 岩相 软沉积物变形 滑塌构造 上奥陶统 蒲塘口剖面 常山 浙西 

分 类 号：P534.42[天文地球—古生物学与地层学]