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现代地质 ›› 2012, Vol. 26 ›› Issue (3): 508-517.

• 煤田地质学 • 上一篇    下一篇

重庆地区晚二叠世层序-古地理及聚煤特征

 高彩霞1,2,3, 邵龙义1, 朱长生2,3, 双燕2,3, 李长林2, 高彩红1   

  1. 1 中国矿业大学 地球科学与测绘工程学院 煤炭资源与安全国家重点实验室,北京100083;2 重庆地质矿产研究院 外生成矿与矿山环境重庆市重点实验室,重庆400042;3 煤炭资源与安全开采国家重点实验室 重庆研究中心,重庆400042
  • 收稿日期:2011-11-29 修回日期:2012-04-28 出版日期:2012-06-07 发布日期:2012-06-14
  • 通讯作者: 邵龙义,男,教授,博士生导师,1964年出生,煤田地质及环境科学专业,主要从事环境地球化学及煤田地质学的教学与研究工作。Email:ShaoL@cumtb.edu.cn。
  • 作者简介:高彩霞,女,博士研究生,1983年出生,矿产普查与勘探专业,主要从事沉积学及岩相古地理的研究工作。Email: gaocaixia_004@163.com。
  • 基金资助:

    国家自然科学基金项目(41030213);国土资源大调查项目(1212010633901)。

Sequence palaeogeography and Coal Accumulation of Chongqing Area in Late Permian

 GAO  Cai-Xia-1,2,3, SHAO  Long-Xi-1, SHU  Chang-Sheng-2,3, SHUANG  Yan-2,3, LI  Chang-Lin-2, GAO  Cai-Gong-1   

  1. 1 State Key Laboratory of Coal Resources and Safety Mining,Department of Resources and Earth Sciences,China University of Mining and Technology, Beijing100083,China;2 Chongqing Key Laboratory of Exogenic Mineralization and Mine Environment,Chongqing Institute of Geology and Mineral Resources, Chongqing400042, China;3 Chongqing Research Center of State Key Laboratory of Coal Resources and Safe Mining,Chongqing400042, China
  • Received:2011-11-29 Revised:2012-04-28 Online:2012-06-07 Published:2012-06-14

摘要:

采用EXXON公司“Vail”学派的观点,将晚二叠世划分为2个三级层序。层序Ⅰ发育低位体系域、海侵体系域及高位体系域,比较完整。层序Ⅱ只发育海侵体系域及高位体系域。通过绘制各种单因素等值线图,并与单井剖面相和连井剖面相分析相结合,从点到线再到面,展开古地理分析。2个层序均反映出海侵自东向西的脉动推进、东深西浅的格局,从而产生了潮坪三角洲-海湾(泻湖)-潮坪-浅海沉积模式在垂向上和平面上的展布特征,其中海湾-潮坪及碳酸盐台地构成了研究区基本骨架。物源区主要来自西部康滇古陆。总体上晚二叠世研究区遭遇了一个海水自东北向西南不断侵进的过程,因此成煤环境随着海平面的上升而不断向西南迁移。煤层主要发育在海湾-潮坪环境里,其次为低地残积平原。

关键词: 层序地层, 岩相古地理, 重庆地区, 晚二叠世

Abstract:

The sequence stratigraphy and palaeogeography of the Late Permian Longtan and Changxing formations in Chongqing area of southwestern China have been studied based on the data of outcrops and borehole sections. A total of two thirdorder sequences are subdivided in the Late Permian; sequence Ⅰ is from the bottom of Longtan Formation to the bottom of C16 coal seam in Longtan Formation, representing a transgressive to regressive cycle; sequence Ⅱ is from the bottom of C16 coal seam in Longtan Formation to the top of Changxing Formation, representing a second regional transgressive to regressive cycle.The palaeogeographic maps of two sequences have been reconstructed based on the contour maps of a variety of palaeogeographic parameters including the  total thickness of strata, the thickness of sandstone, the thickness of limestones, the thickness ratio of siliciclastic rocks to carbonates and siliceous rocks, and the thickness ratio of sandstones to mudstones, as well as the thickness of the total coal seams.Both of the two sequences reflect a vertical and lateral pattern of palaeogeography, which shows that, from the bottom to the top and from the southwest to the northeast, there is a variation in facies units from the tidal flatdelta combination, through the bay lagoon tidal flat combination, to the shallow marine combination.In the two sequences, depositional environments are all deeper in the northeast, and shallower in the southwest, with the transgressive pulse of advancing from northeast to southwest.The sediment provenances were mainly from the Kangdian oldland to the west.The favorable coal forming facies units are mainly the bay tidal flat facies, followed by residual plain facies, and in the two sequences these facies units controlled coal distribution and they moved towards southwest with a continuous sea level rise.The thick coal zone in sequence Ⅰ is distributed in the area bordered by the Liangping Fuling Wansheng line to the east, and by the Tongliang Jiangjin Xishui line to the west, and the thick coal zone in sequence Ⅱ is distributed in the southwestern area restricted by Guang an Changshou Nanchuan line to the east with the coal accumulation center located in the Hechuan Chongqing Qijiang zone.

Key words: sequence stratigraphy;lithofacies palaeogeography, Chongqing area;Late Permian