摘要
柴达木盆地北缘地区在泛非-祁连期经历了复杂的洋陆转化阶段,于寒武纪-奥陶纪发育了汇聚板块边缘的沟-弧-盆体系,形成了NWW-SEE向展布的柴北缘构造带早古生代岛弧及弧后盆地,沉积了一套碳酸盐岩-碎屑岩-火山岩建造。在此期间,柴北缘古洋壳的俯冲消减作用及欧龙布鲁克微地块和柴达木地块的汇聚作用与欧龙布鲁克微地块南缘沉积类型的发展演化之间存在有机的联系,构成了完整的盆-山耦合体系,引发了一系列构造事件、火山喷发事件及多种类型的事件沉积等。其中欧龙布鲁克微地块整体位于滩间山岛弧北部,在早古生代发生构造背景的转变,由被动大陆边缘转为活动大陆边缘,并诱发了多期火山喷发事件,在柴北缘构造带内形成多套火山岩、火山碎屑岩以及变碎屑岩夹层,同时陆-弧碰撞造山导致的陆壳基底的隆升及大量岛弧物质为稍后期的盆地内部碎屑岩沉积提供了重要物源。与此同时,欧龙布鲁克微地块由稳定型浅水碳酸盐岩台地沉积陷落为深水斜坡环境,在盆地内早奥陶世晚期系有规律地集中发育碳酸盐岩滑塌沉积及重力流沉积(海底扇,浊积岩等)。在此之后,由于岛弧物质向盆地内部提供大量碎屑物质,且陆-弧碰撞触发的火山及地震活动导致了同时期大量的碎屑重力流沉积的发育,并触发相对深水区沉积物向更深水区移动,使得其沉积类型转化为浊流沉积。统计表明上述事件沉积发育的时间与柴北缘地区构造活动相对活跃期基本一致,因此这些早奥陶世晚期厚层、多期次、非稳定性的重力流砂体为柴北缘洋陆俯冲及陆-弧碰撞背景下形成的,它们之间存在耦合关系。
The North Qaidam Orogenic Belt experienced a complicated ocean-land transformation process in the PanAfrican-Qilian period,and developed a trench-arc-basin system in the convergent margin in the Cambrian-Early Ordovician. Consequently,the NWW-SEE trending Tanjianshan island arc belt and the South Oulongbuluq back-arc basin formed along the North Qaidam Orogenic Belt,and developed a set of carbonate-clastic-volcanic sedimentary formations. During this time,a basin-scale coupling system was formed between sedimentary evolution of the southern margin of the Oulongbuluq microcontinent and convergence forces between it and the Qaidam block,triggering a series of geological events. They are linked by a series of genetic mechanisms,which have a common macroeconomic background. In the Early Paleozoic era a tectonic shift from passive to active continental margin occurred at the southern margin of the Oulongbuluq microcontinent,as a consequence of northward subduction by the North Qaidam Ocean. This induced multi-period volcanic eruption events,and formed numerous sets of volcanic rocks,pyroclastic rocks and intercalated metamorphic clasolite in the Tanjianshan island arc belt. Meanwhile,the southern margin of Oulongbuluq microcontinent changed from a shallow water carbonate platform to deep water slope,and regularly developed concentrated event deposits such as carbonate gravity flow deposits(submarine fan,turbidite,etc.)and slumping deposits. In addition,a mass of island-arc material and uplifted continental crust basement caused by subsequent collision between the Tanjianshan island-arc belt and the Qaidam block provided important provenance for subsequent sandy debris flow and clastic turbidite deposition in the South Oulongbuluq back-arc basin. The isotopic chronology data shows that the development time of these event deposits is consistent with the relatively most active period of tectonism at the northern margin of the Qaidam Basin area and early in the Paleozoic. Therefore,these stable-distribution volcanics and gravity flow deposits with concentrated and regular distribution formed in the aftermath of subduction and arc-continent collision,and there is a coupling relationship between them.
作者
马帅
陈世悦
孙娇鹏
贾贝贝
王志金
MA Shuai;CHEN ShiYue;SUN JiaoPeng;JIA BeiBei;WANG ZhiJin(School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266555,China;Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China;Dongsheng Company of China Petrochemical Shengli Oilfield,Dongying,Shandong 257100,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2019年第4期674-689,共16页
Acta Sedimentologica Sinica
基金
中国地质调查局项目（12120115003301）~~
关键词
柴达木盆地北缘
早古生代
事件沉积
耦合关系
northern margin of Qaidam
Early Paleozoic
event deposit
coupling relationship
