塔北古隆起的三维地质结构及相关问题探讨

Three-dimensional geological modeling of the Tabei paleo-uplift and discussion on related issues

盆地深层构造地质学的研究可以揭示沉积盆地早期的物质记录,揭示盆地深层地质结构、构造样式及其变化特点,还原构造-古地理环境等。塔北古隆起是塔里木盆地油气最富集的构造单元之一,是研究板块内部变形的理想场所。对塔北古隆起地质结构的精细解析有利于加深对古隆起控油气理论的理解,对深层海相油气勘探具有指导意义。文中基于整个塔北地区的地震资料以及大量钻井资料,建立其三维地质结构,通过Petrel软件实现三维可视化。塔北古隆起存在12个不整合面,可划分为五大构造层:基底(AnZ)、震旦系—下古生界(Z-S)、上古生界(D3d-P)、中生界(T-K1)、新生界(E-Q)构造层。塔北古隆起的地质结构受其深层主干断裂系统控制,依据深层主干断裂发育模式的差异,可将古隆起分为4段:(Ⅰ)温宿凸起段;(Ⅱ)英买力低凸起段;(Ⅲ)哈拉哈塘凹陷与轮南低凸起段;(Ⅳ)草湖凹陷与库尔勒鼻状凸起段。哈拉哈塘凹陷-库尔勒鼻状凸起(甚至包括孔雀河斜坡)的古生界构造层保留了NE-SW向的古生代构造形迹,与近E-W向深层主干断裂系统斜交,可能指示塔北古隆起在晚古生代处于右旋压扭性或NW-SE向主应力环境,直到侏罗纪—早白垩世才发生改变。

Structural geology of deep sedimentary basins can reveal the basins’early stage material records as well as their geological structures,structural styles and changing characteristics,and restore the basins’tectono-paleogeography.The Tabei paleo-uplift is one of the most petroleum rich tectonic elements in the Tarim Basin,making it an ideal place to explore the deformation behaviors in the interior of the tectonic plates.Through detailed geological structural studies,we can enhance our understanding of the paleo-uplift control theory for guiding deep marine petroleum exploration.In this paper,based on seismic and drilling data covering most northern Tarim Basin,we developed a 3-D geological model of the Tabei paleo-uplift and performed the Petrel 3-D visualization.The Tabei paleo-uplift has twelve unconformities and can be divided into five structural layers:basement(AnZ),Sinian-Lower Paleozoic(Z-S),Upper Paleozoic(D3d-P),Mesozoic(T-K1)and Cenozoic(E-Q)structural layers.The structural framework of the Tabei paleo-uplift is controlled by its major fault system and can be divided into four segments according to developmental variations of the major fault:(Ⅰ)the Wensu uplift;(Ⅱ)the Yingmaili lower uplift;(Ⅲ)the Halahatang sag and Lunnan lower uplift;and(Ⅳ)the Caohu sag and Korla nose-shaped uplift.The Halahatang Sag-Korla nose-shaped uplift(may even include the Kongquehe slope)retains the Paleozoic structural features of NESW trending,and makes an oblique crossing with the NEE-SWW trending major fault system.We hypothesize that dextral transpression might have been the main tectonic setting during the Paleozoic until the JurassicEarly Cretaceous.