塔里木盆地古生代盆地类型及板块运动特征

Type of Paleozoic basin and feature of plate movement in Tarim basin

应用层序地层学研究方法将塔里木盆地古生界划分为9个层序,27个体系域。体系域研究表明,自寒武纪到二叠纪依次发育了碳酸盐岩台地、被动大陆边缘、克拉通内盆地、前陆盆地等多种沉积类型。以板块构造理论为指导,结合古地磁资料,对沉积盆地类型与构造演化之间的关系及构造作用对盆地的改造进行了探讨。从活动论的观点解释了塔里木盆地古生代各时期所处的地理位置、板块活动性质、盆地类型及沉积特点。认为古生代塔里木板块在漂移过程中与相邻板块碰撞,使其漂移轨迹呈“S”形。由于受板块运动性质的影响,塔里木盆地在古生代不同时期具有不同的盆地类型:寒武纪—早奥陶世,塔里木为一个离散边缘的克拉通盆地;早奥陶世末—早古生代末,塔里木板块东部(今南部)洋壳消减,形成东部的会聚边缘弧后前陆盆地和北部的离散边缘被动大陆边缘盆地两种不同类型盆地共生的构造格局;志留纪—泥盆纪,塔里木板块西北缘的天山洋闭合,塔里木板块与哈萨克斯坦板块开始发生碰撞,形成了克拉通内盆地;石炭纪塔里木板块西南缘为离散边缘,形成被动大陆边缘盆地;二叠纪塔里木为前陆盆地。

Using sequence-stratigraphic study approach to divide Paleozoic of Tarim basin into nine stratigraphic sequences and 27 systems. The system study shows the multiple sedimentary types such as carbonate platform, passive continental margin, cratonic basin-interior basin and foreland basin are developed successively from Cambrian to Permian. Taking the plate structure theory as a guide and combining with palaeomagnetic data, we discuss the relationship between the type of sedimentary basin and structural evolution and the reforming role of tectonic action on basin. From movement theory, we interpret the geographic position, nature of plate activity, basin type and sedimentary feature in separate epoch of Paleozoic in Tarim basin. It is considered that Paleozoic Tarim plate came into collision with adjacent plates during drift, which made its drift trail show “S” pattern. Since affected by the nature of plate movement, Tarim basin had different types of basin in different period of Paleozoic: Tarim basin was cratonic basin with discrete margin from Cambrian to Early Ordovician; from the late of Early Ordovician to the late of Early Paleozoic, the oceanic crust in eastern part of Tarim plate (current south part) diminished, forming such structural setup that two different basin types, eastern convergent margin post-arc foreland basin and northern passive continental margin basin with discrete margin, coexisted; from Silurian to Devonian, the Tianshan ocean in northern margin of Tarim plate sealed, the Tarim plate came into collision with Kazakhstan plate, forming cratonic basin-interior basin; the southwestern margin of Tarim basin in Carboniferous was discrete margin, forming passive continental margin basin; the Tarim basin in Permian was foreland basin.