新疆蛇绿岩时空分布特征及对增生造山过程的制约

Spatiotemporal Distribution of Ophiolite in Xinjiang and Constraints on Accretionary Orogenic Processes

聚焦新疆区内集中出露的61处蛇绿岩,据其物质组成、构造属性、形成时代、空间分布等特征,将其划分为14条蛇绿混杂岩带,其中多处发育洋岛海山、洋内弧等大洋岩石圈岩石组合,并以塔里木-敦煌地块为界,提出以北属古亚洲洋构造域、以南属特提斯洋构造域。结合俯冲增生造山过程中不同阶段的岩石学记录,确认古亚洲洋形成于新元古代末期至晚石炭世,指示了古亚洲洋经历近500 Ma的长期演化过程。原特提斯洋形成于新元古代—早泥盆世,古特提斯洋形成于早石炭—中三叠世,暗示其分别经历了~800 Ma、~100 Ma的演化历史。并以大陆动力学为主线,以增生造山过程的解析为主要手段,对古亚洲洋、特提斯洋的洋陆转换过程进行全面分析总结,将全疆造山过程划分为太古宙—古元古代古陆核的形成、中元古—新元古代中期塔里木古陆及古生代洋中陆块基底的形成、南华—三叠纪阶段新疆大陆地壳的增生与聚合等3个阶段。

According to the material composition,structural properties,formation time,spatial distribution and other characteristics of 61 ophiolite outcrops in Xinjiang,it is divided into 14 ophiolitic melange belts,Oceanic lithospheric rock assemblages such as oceanic islands,seamounts and introceanic arcs are developed in many of them.Taking The Tarim dunhuang block as the boundary,it is proposed that the north belongs to the paleoAsian ocean tectonic domain and the south belongs to the Tethys Ocean tectonic domain.Combined with the petrographic records of different stages in the subduction process,it is confirmed that the Paleo-Asian ocean was formed from the late Neoproterozoic to the late Carboniferous,and indicates that the ancient Asian Ocean experienced a long evolution process of nearly 500Ma.The proto-Tethys Ocean was formed in the Neoproterozoic to the early Devonian,the Paleo-Tethys Ocean was formed from the Early Carboniferous to the Middle Triassic,and implies that it has undergone the evolution of~800Ma and~100Ma respectively.This paper makes a comprehensive analysis and summary of the Ocean-Continent transition process of the Ancient Asian ocean and tethys Ocean,and the orogenic process of xinjiang is divided into three stages,including Archean-Paleoproterozoic formation stage of the ancient continental nucleus,Middle Proterozoic to Neoproterozoic stage of the formation of Tarim Craton and continental basement in Paleozoic Oceanic and the late Neoproterozoic-Triassic stage of continental crust accretion and congregation.