摘要
聂荣微陆块呈透镜体状夹持在班公湖-怒江板块缝合带内,其上出露有黑云母花岗片麻岩以及二长花岗片麻岩等不同类型的古老片麻岩,本文报道产出于聂荣微陆块上花岗片麻岩的锆石LA-ICP-MSU-Pb定年结果,样品锆石的岩浆震荡环带十分发育,多数锆石具有典型的岩浆结晶锆石的特征。所有测点中有16个测点的Th/U值较高,介于0.58～1.24之间,平均值为0.79,获得的206Pb/238U年龄基本一致,加权平均值为819.6±5.2Ma,笔者等认为该年龄代表了花岗片麻岩的原岩结晶时代为新元古代。我们在羌塘南部地区的碎屑岩中获得了同样的年龄峰值(809Ma)。此外,我们认为年龄中具有507Ma左右的信息反映了泛非事件之后另外一次强烈构造热事件的影响在该区的存在。
The Nierong microconfinent was a micro-lens gripping in the Bangong Co-Nujiang River suture zone, there are monzonitegneiss and biotite-monzonite-gneiss in the Nierong microcontinent. We report LA-ICP-MS U-Pb zircon dating results for the granitic gneiss in the Nierong microcontinent. The CL images of the granitic gneiss zircons show distinct oscillatory zoning, indicative most of the zircons were crystallized in granite. Sixteen analyses have high Th/U ratios, the Th/U ratios range from 0. 58 to 1.24, with an average of 0. 79, their U-Pb results form a single, essentially concordant group with a mean 206^Pb/238^ U age of 819 ± 5.2Ma. Reflect that the granitic gneiss was emplaced in the ages of 819. 6 ± 5. 2Ma. We got the same chronology data （809Ma） from the clastic zircon in the south Qiangtang also. We think the ages of 507Ma show that the Nierong microcontinent was effected by another tectonics thermal event after the Late Pan-Mrican motion.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第12期4101-4108,共8页
Acta Petrologica Sinica
基金
国家自然基金项目(41072166
41272240)
中国地质调查局项目(1212011086064)联合资助
