柴北缘构造带泥盆纪构造属性研究

Research on Northern Qaidam tectonic attributes during Devonian

根据露头及钻井资料,依据沉积学理论,对柴达木盆地东北部泥盆系地层厚度、碎屑颗粒组成、锆石年龄、超覆关系和沉积体系展布等进行研究。结果表明：柴北缘地区（包括柴北缘构造带与欧龙布鲁克微板块）泥盆纪发育自南向北展布的沉积体系,碎屑物质来源于由多个前泥盆纪构造岩片组成的造山带;该阶段柴北缘构造带构造属性既不是前陆盆地也不是裂陷槽,而是由多个前泥盆纪构造岩片组成的造山带;该造山带隆升开始于距今约465 Ma,遭受剥蚀开始于距今约430 Ma,其隆升可能持续到晚石炭世甚至二叠纪早期,初步推断该造山带至少存在了190 Ma,包括距今465～430 Ma的山体隆升与距今430～275 Ma的山体剥蚀阶段。

Using rock core and outcrop data,a series of studies were conducted under the sedimentology theories to investigate the formation thickness,detrital components,detrital zircon age,stratigraphic onlap,and the distribution of Devonian sedimentary system in the Northeast Qaidam area. The results show that the Devonian sedimentary system developed in the northern Qaidam area（including Northern Qaidam tectonic belt and Oulongbuke microplate） is distributed from south to north; the orogenic belt composed by several pre-Devonian tectonicslices is the main provenance of the northern margin in the Qaidam area. The northern Qaidam Caledonia tectonic belt in this period was neither a rift valley nor a foreland basin,but a orogenic belt consisting of multiple pre-Devonian geological bodies. The uplift of the orogenic belt started from about 465 Ma years ago,its denudation started from 430 Ma years ago,its uplift history perhaps lasted to the Late Carboniferous even to the Early Permian. The orogenic belt had been existing for at least 190 Ma years,including the mountain uplift period（465- 430 Ma years ago） and the mountain erosion period（430- 275 Ma years ago）.