塔里木盆地寒武系—奥陶系烃源岩发育模式及分布规律

塔里木盆地寒武系—奥陶系烃源岩主要分布于3套层系中,即中—下寒武统的碳酸盐岩烃源岩和泥质岩烃源岩,上寒武统—中、下奥陶统的泥质岩烃源岩和上奥陶统的台缘灰泥丘烃源岩。这些烃源岩在纵向演化上受海平面升降控制,即层序体系域属性不同,烃源岩发育不同;在平面分布上与古水深、沉积相密切相关。泥质类烃源岩主要形成于广海陆棚—深海盆地,深海相泥质类烃源岩的形成是由于表层水体中大量生物的死亡堆积到深水环境中,由于深水缺氧,有利于有机质保存,加上远离陆地,沉积速率低,使得有机质富集;广海陆棚相泥质类烃源岩的形成与上升洋流的作用有关。碳酸盐岩烃源岩的形成是受层序体系域和沉积相控制,分布于下斜坡的高位体系域或与膏盐岩伴生。

Development Pattern and Distribution Rule of Source Rock of Cambrian-Ordovician in Tarim Basin

Source rock is mainly distributed in three series of strata in Cambrian-Ordovician in Tarim Basin,(i.e.) carbonate source rock and mud source rock in Middle-Low Cambrian,mud source rock in Middle-Lower Ordovician-Upper Cambrian,platform margin lime-mud mound source rock in Upper Ordovician.The development of source rock is controlled by eustatic sea level change in vertical direction,and dominated by facies and palaeowater depth in plane.The mud source rock is mainly formed in continental shelf-deep basin.Mud source rock in deep-sea basin is due to lots of lethal bionts in surface waters which is accumulated in deep water environment.Because of absent oxygen and low aggradation rate in deep water,organic matter is prone to be kept.The mud source rock in open-sea continental shelf is related with the function of ascent ocean current.The carbonate source rock is controlled by system tracts and facies.The carbonate source rock is mainly developed in high system tract in low ramp or is survived with gypsum-salt rock together.