渝东北下寒武统水井沱组陆棚相黑色页岩沉积演化特征

渝东北地区位于四川中生代前陆盆地和扬子陆块南部被动边缘褶冲带的结合部位，形成东西向密集、大体平行、不对称的背、向斜构造。研究区下寒武统水井沱组发育在克拉通内坳陷形成的滞留盆地沉积环境中，是页岩气富集层位，埋藏深，岩相组合变化大。本文利用地层剖面组合、岩性、标准层、地层厚度和地球化学指标等将水井沱组页岩地层划分为两个三级层序（SQ1、 SQ2），每个层序又进一步划分为两个体系域，即海侵体系域TST和高位体系域HST。通过野外剖面沉积相分析和沉积相平面展布特征的研究，结合连井剖面、黑色页岩分布规律等分析该区陆棚相黑色页岩沉积演化特征。研究结果表明：该套页岩主要由浅海深水陆棚相、浅水陆棚相和砂质陆棚相组成，为3种陆棚亚相沉积。

The sedimentary evolution characteristics of continental shelf facies black shale of Lower Cambrian Shuijingtuo Formation in Northeast Chongqing

The northeast area of Chongqing is in the joint part of thrust—fold belt of Mesozoic Sichuan foreland basin and southern margin of Yangtze landmass， structurally forming asymmetric anticline and syncline which are dense in E-W trending and parallel in general. Lower Cambrian Shuijingtuo shale developed in stagnant marine basin formed by continental margin， intercratonic depression and foreland flexure with deep buried depth， varying lithofacies associations. In this paper， we make use of strata combination， lithology， fossil， marker bed， formation thickness and geochemical indicators to divide Shuijingtuo shale into two third—order sequences（SQ1 and SQ2）， and each sequence is further divided into two system tracts， TST and HST. Through analyzing sedimentary facies and the distribution， combining well tie profiles， black shale distribution and geochemical elements， the results show that Lower Cambrian Shuijingtuo Formation are neritic deep shelf deposit， and shallow shelf deposit as well as arenaceous shelf deposit.