塔里木盆地寒武系-奥陶系泥质烃源岩发育的构造和沉积背景控制

塔里木盆地寒武系-奥陶系是主力烃源岩发育层段，而泥质岩烃源岩则是此时满加尔坳陷及其周边地区的主要烃源岩类型。通过露头和钻井资料，结合盆地区域构造演化分析可知，塔里木盆地寒武系-奥陶系泥质烃源岩主要沉积在具上升洋流的陆棚、滞流的海湾陆棚、正常陆棚、深海盆地以及淹没台地陆棚等不同的环境中。它们分别属于伸展的被动大陆边缘、伸展的裂陷槽盆和稳定的克拉通构造背景。这些沉积在不同构造和沉积背景中的泥质烃源岩，其有机质含量具有较大的差异，具上升洋流的陆棚环境中形成的泥质烃源岩中有机质含量最高，其次是滞流的海湾陆棚环境中形成的泥质烃源岩，正常陆棚环境中形成的泥质烃源岩的有机质含量相对较低，而真正深海洋盆环境中沉积的泥质沉积物中的有机质含量远不如陆棚环境中的泥质沉积物。淹没台地陆棚环境中沉积的泥质岩中有机质含量最低。这说明塔里木盆地构造和沉积背景对海相泥质烃源岩发育具有重要的控制作用。

Sedimentary-tectonic Control on the Development of Muddy Hydrocarbon Source Rocks of Cambrian-Ordovician from Tarim Basin

Cambrian-Ordovician is the main horizon for the development of hydrocarbon source rocks in Tarim Basin.The muddy hydrocarbon source rocks are the dominant type for the Manjiaer Depression and its surrounding in this period.According to the data from outcrop sections and wells along with the analysis of basin tectonic evolution,it can be seen that the environments in which the muddy hydrocarbon source rocks were deposited include shelf with upper welling activity,normal shelf,restricted bay,deep ocean floor and inundated carbonate platform,and the tectonic settings for these environments belong to passive continental margin,deep rift basin and stable craton,respectively.The concentrations of organic matter for the muddy hydrocarbon source rocks deposited in different sedimentary-tectonic settings are of quite difference.There is the highest TOC concentration in the muddy source rocks deposited in the shelf with upper welling activity,then those in the restricted bay and normal shelf.The TOC concentration in the muddy source rocks deposited in the deep ocean floor is much lower than those in the shelf.There is the lowest TOC concentration in the muddy source rocks deposited in the stable inundated carbonate platform.These facts illustrate the control of sedimentary-tectonic settings on the development of marine muddy hydrocarbon source rocks.