柴达木盆地北缘前泥盆纪构造格架及欧龙布鲁克古陆块地质演化

The Pre-Devonian tectonic framework in the northernmargin of Qaidam basin and geological evolutionof Olongbuluck palaeo-block

最近 ,越来越多的区域地质、地球化学和同位素地质年代学等证据表明 ,柴达木盆地北缘前泥盆纪由北向南可以划分为 3个构造单元 ,北部为古元古代形成的欧龙布鲁克古陆块 ,中间为经历过多次叠加改造的沙柳河—鱼卡超高压碰撞带 ,南部为中元古代形成的柴达木陆块。欧龙布鲁克古陆块自古元古代以来保存了丰富的地质记录 ,反映了其复杂的地质演化历史。综合区内沉积作用、岩浆活动、变质作用和构造运动等特征 ,将欧龙布鲁克古陆块地质演化由老到新分为 7个演化阶段 ,即古元古代古陆块形成阶段、中元古代陆内沉降阶段、中—新元古代Rodinia超大陆汇聚阶段、南华纪—震旦纪Rodinia超大陆裂解阶段、早古生代陆块俯冲与折返阶段、晚古生代—中生代陆内造山阶段和中新生代高原隆升阶段。研究本区古陆块的汇聚与裂解过程 。

Recently, more and more evidences from regional geology, geochemistry and geochronology indicate that the northern margin of Qaidam basin in the Pre-Devonian can be divided into three tectonic units from north to south; they are the Olongbuluck paleo-block, the Shaliuhe-Yuqia UHP belt, and the Qaidam block. There are abundant geological records preserved in the Olongbuluck palaeo-block since the Paleoproterozoic, which reflect the complicated geological evolution history of the block. Integrating the characteristics of the sedimentation, of the magma activity, of the metamorphism and of the tectonic movement in this area, the geological evolution of the Olongbuluck paleo-block can be subdivided into seven phases: the Paleoproterozoic paleo-block forming phase, the Mesoproterozoic inner-continental sinking phase, the Meso-Neoproterozoic collision of Rodinia, the Nanhua-Sinian break-up of Rodinia, the Early-Paleozoic block underthrusting and backfolding phase, the Late-Paleozoic to Mesozoic inner-continental orogenetic movement, and the Mesozoic-Cenozoic plateau rising up. The study of the processes of collision and break-up of these blocks will provide significant evidences for understanding the correlation between North China and Yangtze block and their interaction history.