石油与天然气地质 ›› 2018, Vol. 39 ›› Issue (6): 1201-1212.doi: 10.11743/ogg20180610

• 油气勘探 • 上一篇    下一篇

鄂尔多斯盆地西缘中奥陶统克里摩里组深水等深流溢岸混合沉积

李向东1, 阙易1, 郇雅棋2, 陈海燕1   

  1. 1. 昆明理工大学 国土资源工程学院, 云南 昆明 650093;
    2. 中国石油 冀东油田分公司, 河北 唐山 063200
  • 收稿日期:2017-10-11 修回日期:2018-08-20 出版日期:2018-12-28 发布日期:2018-10-22
  • 作者简介:李向东(1973-),男,博士、讲师,沉积学。E-mail:lixiangdong614@163.com。
  • 基金资助:
    国家自然科学基金面上项目(41272119)。

Mixed carbonate-siliciclastic sequences of deep-water contour current overflow origin of Kelimoli Formation in Zhuozishan area,western margin of Ordos Basin

Li Xiangdong1, Que Yi1, Huan Yaqi2, Chen Haiyan1   

  1. 1. Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China;
    2. Jidong Oilfield Branch Company Ltd., PetroChina, Tangshan, Hebei 063200, China
  • Received:2017-10-11 Revised:2018-08-20 Online:2018-12-28 Published:2018-10-22

摘要: 鄂尔多斯盆地西缘桌子山地区中奥陶统克里摩里组普遍发育深水等深流沉积,其中石峡谷剖面发育完整,岩性变化明显,为达瑞威尔期等深流沉积的理想剖面。以石峡谷剖面克里摩里组中段为研究对象,在详细的野外观察基础上,结合室内岩石薄片研究、相关地球化学测试和已有的研究成果,探讨石灰岩岩组与页岩互层的形成机制。结果表明:克里摩里组中段共发育10个石灰岩岩组可划分为3个旋回;单层石灰岩以不同的透镜体形态及样式尖灭于页岩之中;石灰岩中发育平行层-均匀层-平行层序列和平缓微波状条纹构造,在显微镜下表现为交替的灰泥和粉晶聚集带。结合已有研究成果综合判断认为:克里摩里组中段石灰岩与页岩组成混积层系,包含有陆源碎屑与碳酸盐混积层系及碳酸盐(陆源碎屑岩)与混积岩混积层系2种类型,可能为受天文旋回控制的深水等深流周期性溢岸混合沉积所致。克里摩里组中段深水等深流成因混积层系的发现对于鄂尔多斯盆地西缘奥陶系页岩气的勘探具有重要意义。

关键词: 碳酸盐岩, 混合沉积, 等深流, 奥陶系, 桌子山地区, 鄂尔多斯盆地

Abstract: The deep-water contourites are widely developed in the Middle Ordovician Kelimoli Formation in Zhuozishan area,western margin of Ordos Basin.The Shixiagu outcrop thereto is generally regarded as an ideal section for studying the contourites of the Darriwilian stage for its complete stratum and obvious lithological variations.Here we focus on the mechanism of limestone associations alternating with shale in the middle Kelimoli Formation based on outcrop observations,study of thin sections in labs,data from relevant geochemical tests and previous works.The results show that: ① the middle part of Kelimoli Formation consists of ten limestone associations which could be grouped into three cycles; ② the single limestone layer pinches out in shale with different forms and patterns of lens; ③ a succession of parallel layer-homogeneous layer-parallel layer and streaky structures in the shape of gentle ripples are developed in the limestone,displaying alternating zones of lime mud and very fine crystalline under microscope.In combination of previous research,we may conclude that the mixed sequences consisting of limestone and shale in the middle Kelimoli Formation can be divided into two types,one is the mixed sequence of terrigenous clastics with carbonate,and the other is the mixed sequence of carbonate(terrigenous clastics)with diamictite,and their genetic mechanism could be attributed to the periodic overflow of contour current controlled by astronomical cycles in deep-water slope environment.The discovery of mixed sequences caused by deep-water contour currents can be of great significance for the Ordovician shale gas exploration at the western margin of Ordos Basin.

Key words: carbonate rock, mixed deposition, contour current, Ordovician, Zhuozishan area, Ordos Basin

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