阿尔金山东段奥陶纪火山-沉积体系及构造意义

摘要

出露于阿尔金山北坡的厚度巨大、基本不变质的海相沉积地层,岩性以火山岩、碎屑岩、碳酸盐岩为主.研究表明,该地层年代为奥陶纪中晚期.沉积特征具有限洋盆边缘向洋中脊扩张中心变化特征,沉积环境为:冲洪积扇→滨岸(碳酸盐台地)→浅海(海山)→半深海→洋脊火山岩,所含火山岩为以拉斑系列玄武岩为主的基性火山岩.岩石化学特征表明,除具明显洋壳特征外,由于位于大陆板块边缘(塔里木板块),还留有大陆板块烙印.因此,本地区早古生代火山沉积体系为形成于大陆板块边缘有限洋盆.%Exposed in the North Slope of Altun of huge thickness,basic constant Marine sediments of strata, whose lithology mainly in the volcanic rocks , clastic rocks, carbonate rocks. The recent studies showed that the formation time of the stratum is middle-late time of Ordovician.Deposition characterized by limited ocean basin margin to the mid-ocean ridge spreading centers , the depositional environment becomes Alluvial Fan-shore(carbonate platform)-shallow water(kop)-bathyal-ridge volcanic rocks.It Contained volcanic basalt.The volcanic basalt is mafic volcanic rocks which mainly in tholeiite series basalt.The rock chemical characteristics show that obvious oceanic crust characteristics,and left a deep imprint of the continental plate ,because it is located in the mainland of the plate (the tarim plate) the edge,so that the Early Paleozoic volcanic sedimentary system of this region formed in a limited ocean basin at the edge of the continental plate.