地学前缘 ›› 2020, Vol. 27 ›› Issue (4): 82-97.DOI: 10.13745/j.esf.sf.2020.4.21

• “第四届全国青年地质大会论文”专栏 • 上一篇    下一篇

柴达木旺尕秀煤矿东南晚侏罗世—早白垩世风成砂古风向及古地理意义

陈政宇,柳永清,江小均,孔志岗,高万里,钱涛,旷红伟,许欢   

  1. 1. 昆明理工大学 国土资源工程学院 地球科学系, 云南 昆明 650093
    2. 中国地质科学院 地质研究所, 北京 100037
    3. 中国地质科学院 地质力学研究所, 北京 100081
    4. 东华理工大学 地球科学学院, 江西 南昌 330013
  • 收稿日期:2019-10-13 修回日期:2020-03-20 出版日期:2020-07-25 发布日期:2020-07-25
  • 通讯作者: 江小均(1985—),男,副教授,硕士生导师,主要从事沉积与大地构造学研究。
  • 作者简介:陈政宇(1993—),男,硕士研究生,从事沉积岩与岩石地球化学研究。E-mail:305250003@qq.com
  • 基金资助:

    国家重点研发计划课题项目(2018YFC0604201);国家自然科学基金面上项目(41673060);中国地质调查局项目(DD20160173,DD20189614)

Paleo-wind direction and paleogeographic significance of Late Jurassic to Early Cretaceous anemoarenyte in the southeastern Wanggaxiu coal mine, Qaidam Basin

CHEN Zhengyu,LIU Yongqing,JIANG Xiaojun,KONG Zhigang,GAO Wanli,QIAN Tao,KUANG Hongwei,XU Huan   

  1. 1. Department of Earth Sciences, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China
    2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
    3. Institute of Geological Mechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
    4. School of Earth Sciences, East China University of Technology, Nanchang 330013, China
  • Received:2019-10-13 Revised:2020-03-20 Online:2020-07-25 Published:2020-07-25

摘要:

柴达木盆地是我国西部地区的主要含油气盆地之一,对其油气勘探和基础地质研究工作已有70余年的历史,取得了大量研究成果,但柴达木中生代原型盆地恢复及构造演化等问题仍存在着诸多争议,影响了盆地的油气勘探进程。项目组对现今柴达木盆地周缘中生代地层开展沉积学、岩石学、沉积相分析等综合地质调查研究,在位于德令哈至都兰国道旺尕秀煤矿东南10 km山沟内原白垩系犬牙沟组地层中,发现一套滨浅湖相风成砂沉积。对其进行1∶100沉积构造厘定和岩石特征剖面实测研究后发现,剖面上发育典型的大型板状斜层理、颗粒流(grain flow)和下降流(fall flow)风成砂构造,并且伴生大量虫迹(traces)、潜穴(burrows)、泥裂和液化弯曲层理潜水位线之下的滨浅湖相沉积构造。同时采集大量组板状交错层理、斜层理等沉积构造古风向产状数据,室内利用古风向数据校正、玫瑰花图绘制进行系统研究,结果显示犬牙沟组风成砂沉积时期应盛行西风和西北风,与中国北方晚侏罗世—白垩纪时期区域研究资料一致。犬牙沟组垂向上显示了风成与水成交互—风成主导—水成主导的变化趋势,表明干湿波动性气候的存在。前人研究认为风成沉积是重要的油气储层,柴达木中生代盆地新发现的一套滨浅湖相风成砂沉积,对于盆地油气勘探有着重要的意义,且能为柴达木中生代盆地原型盆地恢复及构造演化研究提供帮助。

关键词: 柴达木盆地;晚侏罗世&mdash, 早白垩世;风成砂;古风向

Abstract:

The Qaidam Basin is one of the main petroleum basins in western China. Much progress has been made over the past 70 years in the oil and gas exploration and basic geological research in the basin. However, the restoration and structural evolution of the Mesozoic prototype basin in Qaidam are still in dispute, which has affected the petroleum exploration process. In the current project, we conducted a comprehensive geological survey on the sedimentology, petrology and sedimentary facies analysis of Mesozoic strata around the present Qaidam Basin. We first discovered a set of anemoarenyte depositions of coastal and shallow lacustrine facies in the original Cretaceous Quanyagou Formation, located 10 km southeast of the Wanggaxiu coal mine near the Delingha-Dulan Road. Our study on a 1∶100 sedimentary-structural and rock characteristics determination section showed that large tabular cross-beddings, grain and fall flow anemoarenyte structures, and a large number of traces, burrows, mud cracks and liquefied bending bedding structures of coastal and shallow lacustrine facies below the water table developed on the profile. In addition, we collected many paleowind sedimentary structural data, such as tabular cross-bedding and oblique bedding. We also conducted a systematic laboratory study using paleowind direction data correction and rose diagram. The results show that the Quanyagou Formation paleowind is NW directed, consistent with the regional research data from the Late Jurassic to Early Cretaceous in northern China. The vertical successions of the Quanyagou Formation, changing from alternation of aeolian and water laid to aeolian dominated to water laid dominated deposits, indicate climatic oscillation from relatively arid to humid conditions. Previous studies have suggested that aeolian deposition is an important hydrocarbon reservoir. Therefore, the newly discovered set of coastal and shallow lacustrine facies anemoarenyte depositions is of great significance for oil and gas exploration in the Mesozoic Qaidam Basin, and can also help advancing research on the restoration and tectonic evolution of the basin.

Key words: the Qaidam Basin, Late Jurassic to Early Cretaceous, anemoarenyte, paleowind direction

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