摘要
在北祁连柏木峡地区发现的辉长岩、玄武岩以构造岩块形式产出。通过对区内柏木峡地区出露的4处辉长岩、玄武岩的详细野外调查及岩石组合、岩性特征研究,对辉长岩及玄武岩进行了LA-ICP-MS锆石U-Pb同位素测年,首次获得了较为精确的年龄值,分别为(675±31)Ma和(764.1±3.3)Ma,代表了辉长岩、玄武岩的成岩年龄,这一发现结合区域上已经在北祁连山东西段,中南祁连山和柴达木地区获得的大量同位素测年资料,说明这些地区在新元古代可能存在一期重要的岩浆活动,这次岩浆活动可能与同时期全球的Rodinia超大陆裂解有关。结合区域构造演化,认为本地区新元古代形成的辉长岩、玄武岩由于遭受后期强烈的加里东期构造作用的叠加、改造,已变得面目全非,以构造岩块形式残存于柏木峡构造蛇绿混杂岩带中。
The gabbro and basaltare hosted in the Baimuxia Ophiolitemelange belt of North Qilian with the form of various blocks. After carrying out the detailed field investigation and studies of petrology and lithology ongabbro and basalt in the Baimuxia area, the LA-ICP-MS zircon U-Pb dating of gabbro and basalt samples has yielded the accurate ages of （675±31） Ma and （764.1± 3.3） Ma, which can represent theirdiagenetic ages. The results reveal that one important magmatic activity may be existed in the North Qilian area during Middle Neoproterozoic, which could be related to the global cracking of Rodinia supercontinent. The dating of LA-ICP MS zircon U- Pb provide accurate geochronological constraints for studying the formation and evolution of the North Qilian tectonic zone.
出处
《西北地质》
CAS
CSCD
2016年第4期32-42,共11页
Northwestern Geology
基金
国土资源大调查青海1∶5万玉龙滩等四幅区调项目成果(1212011121192)
