摘要
塔里木盆地库车坳陷东部阳霞煤矿一带出露绿泥绢云母石英片岩,原被划分为古元古界地层,该片岩中的碎屑锆石呈自形形态,锆石的环带丰富,具有典型的岩浆锆石特点。对锆石进行的ICP-MS U-Pb同位素地质年代学研究表明,锆石的年龄介于1179～794 Ma之间,峰期年龄集中于810～794 Ma,说明该片岩之原岩的沉积上限年龄不早于794 Ma。结合区域资料分析认为,该基底地层应该属于新元古界,形成时代相对较新,因此导致库车坳陷具有较高的地温梯度和较强的构造活动性。此外,在810～794 Ma时塔里木地块东北部发生过岩浆事件,该事件应该与塔里木地块的裂解有关。
Zircons from the chlorite-sericite-quartz schist around the Yangxia coal mine in the eastern segment of the Kuche depression are characterized by its idiomorphic textures and abundant magmatic zonal structures, so they belong to magmatic zircons. Isotopic ages of zircons by means of ICP-MS U-Pb are between 794 Ma and 1 179 Ma with peak age of 810 - 794 Ma. To combine with the regional geological data, the schist should belong to Neo-proterozoic rather than Paleo-proterozoic, and such results in the higher geothermic gradient and the stronger activity of the basement. Furthermore,magmatic events of 810 ~ 794 Ma probably occur in the north-eastern part of the Tarim blocks, and such events should be related with splitting of the Tarim block in Neo-proterozoic.
出处
《地质科学》
CAS
CSCD
北大核心
2011年第2期475-482,共8页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
库车坳陷
基底
古元古界
新元古界
锆石U—Pb测年
Kuche depression, Basement, Paleo-proterozoic, Neo-proterozoic, Zircon U-Pb isotopic age determination
