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    塔东北库鲁克塔格地区震旦-奥陶纪地质事件及生储盖组合

    The geological event and the assemblage of source-reservoir-seal rock during the Sinian-Ordovician period in Kuruktag region of northeastern Tarim Basin

    • 摘要: 塔里木盆地库鲁克塔格地区是重要的油气资源战略接替区域之一,其特殊的构造背景成为研究盆山耦合及区域构造演化的有效切入点。冰川、火山、风暴、浊流等事件沉积的产物,广泛发育于塔东北库鲁克塔格地区震旦—奥陶系的地层中。这些地质事件的发生时期与库鲁克塔格地区的构造演化具有明显的耦合关系。Rodinia超大陆的裂解是全球新元古代冰川沉积的诱发因素,也使库鲁克塔格地区在震旦纪发育冰川相的沉积。发生于早寒武世的火山事件也是Rodinia超大陆同期裂解的表现。在塔东北地区,裂解导致的持续拉张作用一直延续到早奥陶世末期,但在晚寒武世曾发生过一次持续时间较短的构造反转,区域构造应力场由拉张转为挤压,导致南、北沉积相区水体变浅,受到风暴作用影响。在挤压的区域构造背景下,中—晚奥陶世库鲁克塔格急剧隆升,物源供给的加大,为浊流事件的沉积提供了有利条件。另外,区域的构造背景变化也对于该地区的源岩和储层的产生起了决定性的因素。在震旦—早奥陶世晚期拉张的大地构造背景下,早—中寒武世及早奥陶世成为烃源岩的主要形成时期。优质储层主要为碳酸盐岩及碎屑岩,发育于晚震旦世、晚寒武世、中—晚奥陶世。孔隙类型主要为晶间孔、溶孔、裂缝等。这些源岩和储层与地层中的泥岩在垂向上组成多套生储盖组合。

       

      Abstract: Kuruktag region of Tarim Basin is one of the most important strategic replacement areas of oil and gas resources, and is an effective entry point based on special structural setting for studying basin-mountain coupling and evolution of regional structures. Events deposited products from glacial event, volcanic event, storm event and turbidity event are developed widely in the Sinian-Ordovician sedimentary strata of Kuruktag region on the northeastern margin of Tarim Basin. The formation time of these events has obvious coupling relationship with tectonic evolution of Kuruktag region. The breakup of Rodinia supercontinent was a inducing factors for global glacial deposition of Neoproterozoic, which caused the formation of glacialfacies in the Kuruktag region. In addition, volcanic event in Early Cambrian was also a reflection of the breakup of Rodinia. Continuous tension caused by cracking continued until the end of Early Ordovician. However, shorter-period reversed structures occurred during the late Cambrian, which led to the shallowing of south and north facies and caused the formation of tempestuous deposits. The rapid uplift of Kuruktag Mountain under the pressing structural surroundings during the Middle-Late Ordovician caused the increase of material source, which offered advantage conditions for turbidity event. In addition, changing of regional tectonics was a decisive factor for the development of source rocks and reservoirs. Early and Middle Cambrian as well as Early Ordovician constitute a main stage for the development of source rocks under the extension condition. High-quality reservoirar of pore type comprised bonatite and clastic rocks, and the pores were intracrystalline pores, dissolved pores and cracks mainly distributed in Late Sinian, Late Cambrian and Middle-Late Ordovician strata. These source rocks and reservoirs with mudstone formed multiple source-reservoircaprock association in the vertical direction.

       

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