石油学报 ›› 2015, Vol. 36 ›› Issue (1): 19-32.DOI: 10.7623/syxb201501003

• 地质勘探 • 上一篇    下一篇

渤海湾盆地东濮凹陷古近系沙河街组盐岩成因——来自沉积学和地球化学的证据

高红灿1, 郑荣才2, 肖应凯3, 孟凡巍4, 陈发亮5, 白工6, 栾艳春5, 谭先锋1, 施玉娥5   

  1. 1. 重庆科技学院石油与天然气工程学院 重庆 401331;
    2. 成都理工大学油气藏地质及开发工程国家重点实验室 四川 成都 610059;
    3. 中国科学院青海盐湖研究所 青海 西宁 810008;
    4. 现代古生物学与地层学国家 重点实验室 中国科学院南京地质古生物研究所 江苏 南京 210008;
    5. 中国石油化工股份有限公司中原油田分公司物探研究院 河南 濮阳 457001;
    6. 中国石油化 工股份有限公司中原油田普光分公司 四川 达州 636156
  • 收稿日期:2014-07-11 修回日期:2014-11-13 出版日期:2015-01-25 发布日期:2014-12-09
  • 通讯作者: 高红灿, 男, 1969年11月生, 1995年获成都理工学院地质学专业学士学位, 2007年获成都理工大学沉积学专业博士学位, 现为重庆科技学院副教授, 主要从事沉积学教学与研究工作.Email:gaohongcan@126.com
  • 作者简介:高红灿, 男, 1969年11月生, 1995年获成都理工学院地质学专业学士学位, 2007年获成都理工大学沉积学专业博士学位, 现为重庆科技学院副教授, 主要从事沉积学教学与研究工作.Email:gaohongcan@126.com
  • 基金资助:

    油气藏地质及开发工程国家重点实验室(成都理工大学)开放基金项目(No.PLC201007)、中国博士后科学基金项目(No.20080440125、No.201003403)和国家自然科学基金项目(No.41173051、No.41202043)资助.

Origin of the salt rock of Paleogene Shahejie Formation in Dongpu sag, Bohai Bay Basin: evidences from sedimentology and geochemistry

Gao Hongcan1, Zheng Rongcai2, Xiao Yingkai3, Meng Fanwei4, Chen Faliang5, Bai Gong6, Luan Yanchun5, Tan Xianfeng1, Shi Yu'e5   

  1. 1. School of Petroleum and Natural Gas Engineering, Chongqing University of Science and Technology, Chongqing 401331, China;
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Sichuan Chengdu 610059, China;
    3. Qinghai Institute of Saline Lake, Chinese Academy of Sciences, Qinghai Xining 810008, China;
    4. State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Jiangsu Nanjing 210008, China;
    5. Geophysical Research Institute, Sinopec Zhongyuan Oi lfield Company, Henan Puyang 457001, China;
    6. Puguang Branch, Sinopec Zhongyuan Oilfield Company, Sichuan Dazhou 636156, China
  • Received:2014-07-11 Revised:2014-11-13 Online:2015-01-25 Published:2014-12-09

摘要:

东濮凹陷是渤海湾盆地盐岩最发育的凹陷,其古近系沙河街组主要发育有4套累计超过1 000 m厚的盐岩,其成因颇受争议.通过沉积学和地球化学方法对其进行了研究.盐岩与具纹层状沉积构造的泥页岩相间发育,泥页岩的V/(V+Ni)平均比值为0.736(基本分布在0.64~0.81),其中发育有石盐漏斗晶体并夹有砂质碎屑流块状砂岩等特征,表明具纹层状沉积构造的泥页岩形成于半深湖—深湖的强还原环境.盐岩与泥页岩之间没有侵蚀暴露面,泥页岩层面上也没有干裂沉积构造,盐岩厚度大且较纯净,从而推断盐岩和与其相邻的泥页岩的沉积环境一样,都是半深湖—深湖的强还原环境.纵向上,盐岩发育于层序的湖侵体系域和高位体系域,盐岩发育期也是东濮凹陷的主要裂陷期和扩张期;横向上,盐岩分布于凹陷中央,与凹陷边缘沉积的砂岩呈彼消此长的关系,泥页岩则主要分布于砂岩和盐岩之间的较广阔地区.即盐岩的沉积中心、凹陷的沉积中心及凹陷的沉降中心三者基本一致,盐岩发育期也是湖盆发育的鼎盛期.沉积学的证据支持东濮凹陷盐岩"深水成盐"的观点.在连续沉积的盐岩段,从老地层到新地层,δ37Cl值没有出现逐渐减小的特征,而是呈不规律的变化,说明东濮凹陷沙河街组盐岩应是在温暖潮湿气候条件下一定水深环境中形成的,即"深水成盐".通过与现代峡谷型湖泊和人工河道水库的对比,说明在盐岩发育期东濮凹陷应具较明显的湖水分层特征——"深水成盐"的基础和基本形式,从理论上也支持东濮凹陷盐岩"深水成盐"观点.

关键词: 东濮凹陷, 古近系, 沙河街组, 盐岩成因, 沉积学, 地球化学

Abstract:

Salt rock is mostly developed in Dongpu sag in Bohai Bay Basin, of which the Paleogene Shahejie Formation has mainly developed four sets of salt rocks with thickness of more than 1000 meters. However, there are many disputes on the origin of salt rock. Preliminary studies have been carried using sedimentological and geochemical methods. The salt rock has alternately developed with mud shale of layered sedimentary structure, and the average V/(V+Ni) ratio of mud shale is 0.736 (basically distributed within 0.64-0.81), which has developed halite hopper crystals mixed with sandy debris-flow massive sandstone; these features indicate the mud shale with layered sedimentary structure has been deposited in the strong reducing environment of deep to semi-deep lake. There is no exposed surface eroded between the salt rock and mud shale, and no mud crack structure in the mud shale layer; the salt rock is relatively pure with large thickness. Therefore, it can be concluded that the sedimentary environment of salt rock is the same as the adjacent mud shale, i.e., the strong reducing environment of deep to semi-deep lake. Vertically, the salt rock is developed in the lacustrine transgressive system tract and high stand system tract of sequence, and the development period of salt rock is also the main chasmic and expanding stage of Dongpu sag; horizontally, it is distributed in the center of the sag and has a reciprocal relationship with the sandstone deposited in the margin of the sag, whereas the mud shale is mainly distributed in the broad area between the sandstone and salt rock, i.e., depocenter of the salt rock is basically identical with deposition center and subsidence center of the sag. The development period of salt rock is also a peak period of the development of lake basin. Sedimentary evidences support the viewpoint of "salt deposited in deep water" for the salt rock of Dongpu sag. In the continuously deposited section of salt rock, δ37Cl values is not gradually decreasing from the old strata to the new, but showing irregular changes. These illustrate the salt rock of Paleogene Shahejie Formation of Dongpu sag should have developed in an environment with deep water under warm and wet weather, i.e., "salt deposited in deep water". Moreover, it is illustrated through comparison with modern canyon lakes and artificial river reservoirs that Dongpu sag is obviously characterized by lake stratification during the development period of salt rock, providing the basis and basic form for "salt deposited in deep water", and theoretically supporting the viewpoint of "salt deposited in deep water" for salt rock of Dongpu sag.

Key words: Dongpu sag, Paleogene, Shahejie Formation, origin of salt rock, sedimentology, geochemistry

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