吴驰华, 伊海生, 刘有良, 夏国清, 龚大兴. 内蒙古乌兰盖盆地早白垩世岩相古地理研究及油气地质意义[J]. 地质通报, 2013, 32(8): 1243-1252.
    引用本文: 吴驰华, 伊海生, 刘有良, 夏国清, 龚大兴. 内蒙古乌兰盖盆地早白垩世岩相古地理研究及油气地质意义[J]. 地质通报, 2013, 32(8): 1243-1252.
    WU Chi-hua, YI Hai-sheng, LIU You-liang, XIA Guo-qing, GONG Da-xing. Lithofacies-paleogeographic characteristics of early Cretaceous in Wulangai basin of Inner Mongolia and their oil-gas geological significance[J]. Geological Bulletin of China, 2013, 32(8): 1243-1252.
    Citation: WU Chi-hua, YI Hai-sheng, LIU You-liang, XIA Guo-qing, GONG Da-xing. Lithofacies-paleogeographic characteristics of early Cretaceous in Wulangai basin of Inner Mongolia and their oil-gas geological significance[J]. Geological Bulletin of China, 2013, 32(8): 1243-1252.

    内蒙古乌兰盖盆地早白垩世岩相古地理研究及油气地质意义

    Lithofacies-paleogeographic characteristics of early Cretaceous in Wulangai basin of Inner Mongolia and their oil-gas geological significance

    • 摘要: 乌兰盖盆地白垩系下统大磨拐河组可划分为冲积扇相、湖泊相、湖底扇相3种沉积相类型。以煤层作为等时对比标志层(煤层位于K1d2段),编制了乌兰盖盆地白垩系下统大磨拐河组K1d2—K1d4段地层厚度等值线图、最深煤层深度等值线图和砂泥比等值线图。研究结果表明:乌兰盖盆地中轴线地区在早白垩世时期存在2个深湖相区,这一地区是深色泥岩广泛分布的地区;紧邻深湖区逐渐过渡为灰绿色砂泥岩相的浅湖相带,地形坡度和缓,东南侧和西南侧坡度起伏大,其间发育有2个孤立、平行盆地边缘的浅湖相区;浅湖相区的间隔地带为滨湖相区,岩性主要为1套浅灰色砂岩夹砾岩的组合,盆地沉积物质来源于北部巴音宝力格古陆和南侧大兴安岭古陆。通过岩相古地理展布特征分析认为,乌兰盖盆地下白垩统大磨拐河组(K1d)生烃坳陷位于巴其北坳陷和高力罕坳陷的半深湖—深湖沉积区,该区地层沉积厚度大、范围广,是下一步油气地质调查和勘探的重要层位。

       

      Abstract: Three sedimentary facies in lower Cretaceous Damoguaihe Formation of Wulangai Basin could be recognized, i.e., alluvial fan facies, lakes facies, and sublacustrine fan facies. With the coal seam as the key bed of isochronal correlation (in K1d2 section),the authors compiled the stratigraphic thickness contour diagram and sand/mud ratio contour diagram of K1d2—K1d4 member of Lower Cretaceous Damoguaihe Formation in Wulangai basin. The results show that, in the central part of Wulangai basin, there existed three deep lakes in Early Cretaceous where there were widely distributed dark mudstone, which gradually changed into transitional facies to the north as marked by celadon mudstone, with gentle terrain slope. On the contrary, the slope on the southwest side changed drastically, and shallow lakes were developed which were rolling northeastward, parallel to the basin margin. Between the shallow lakes there was shallow lake beach area, which extended southward and northward to change into ancient land erosion areas. In combination with the characteristics of lithofacies-paleogeography and the organic geochemical indexes of hydrocarbon source rock samples,the authors hold that the hydrocarbon-generating depressions were located mainly in the lower Cretaceous Bayanhua Formation K1d half deep-deep lake deposits of Baqibei depression and Gaolihan depression in the study area.

       

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