The adamellite was founded in the Huashishan area during the 1:50000 regional geological survey in West Kunlun,it emplaced in the Bayi Daban-Huashishan tectonic melange belt.Through LA-ICP-MS Zircon U-Pb Dating,the author got three values,the crystallization age of the adamellite was (99.5±1.1)Ma,formed in the early stage of late Cretaceous,was the production of magma intrusion after collision;Residual nuclear zircon age were (909± 19.5) Ma and (538± 7.7) Ma,the equivalent of Neoproterozoic Qingbaikou period and early Cambrian,represented the age of the remained mass got from the old geological body when the rock was formed,reflected the existence of Neoproterozoic Qingbaikou period transitional basement and Caledonian folding basement beneath Permian-Triassic marginal fault depression zone of the Shenxian Bay.It could be compared with the transitional basement and folding basement founded in the Tianshuihai Lake Basin microcontinent in the north.The results provide new practical data for further study on the geologic-tectonic evolution of West Kunlun orogenic belt,which are of great importance to the recovery and reconstruction of the tectonic frameworks of Proterozoic in China.%西昆仑1∶5万区域地质调查工作在化石山地区发现二长花岗岩体,其侵位于八一达坂-化石山构造混杂岩带内.通过对二长花岗岩进行LA-ICP-MS锆石U-Pb测年,获得3个年龄值,(99.5±1.1)Ma为二长花岗岩结晶年龄,形成时代为晚白垩世早期,是碰撞后岩浆入侵产物;残留核锆石年龄为(909±19.5)Ma和(538±7.7)Ma,相当于新元古代青白口纪和早寒武世,代表岩体形成时从老地质体中捕获的残留体年龄,反映神仙湾二叠—三叠纪边缘裂陷带下部存在新元古代青白口纪过渡基底及加里东褶皱基底,与北邻甜水海微陆块内发现的过渡基底及褶皱基底可对比.该成果对恢复重建中国元古宙构造格局,进一步研究西昆仑造山带地质构造演化提供了新资料,具重要地质意义.
展开▼
