新疆富蕴可可托海—二台断裂带中假玄武玻璃及其围岩的年代学研究  

Ages of Pseudotachylite and Its Wall Rocks from the Keketuohai—Ertai Fault Zone,Xinjiang,Northwest China

作　　者：刘建民[1] 陈柏林[1] 董树文[1] 赵越[1] 刘晓春[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081

出　　处：《地质论评》2009年第4期581-589,共9页Geological Review

基　　金：国家自然科学基金资助项目(编号40472108)的成果

摘　　要：发育在新疆富蕴可可托海—二台断裂带中的假玄武玻璃是古地震断裂快速滑移形成的构造岩。地质产状、显微构造研究表明,这些假玄武玻璃主要由发生重结晶的玻璃质熔融体形成。假玄武玻璃基质的全岩40Ar-39Ar阶段升温方法主阶段和K-Ar年龄分别为282.8±3.8Ma和276.4±7.4Ma。假玄武玻璃所在母岩(黑云母花岗岩和钾长花岗岩)的锆石U-Pb年龄分别为390.4±1.0Ma和396.3±0.1Ma,表明二台断裂带中的假玄武玻璃是在二叠世早期形成的,也说明二台断裂带古地震活动至少可以追溯到晚古生代(早二叠世早期)。尽管二台断裂带是现今仍然活动的地震构造带,但目前所见到的假玄武玻璃是早二叠世时期古地震活动的产物。1931年的富蕴8.0级地震仅仅是沿着二台断裂带发生的多次构造活动的一次活动,与假玄武玻璃之间没有成因上的联系。The pseudotachylite developed along the Keketuohai--Ertai fault zone in Xinjiang, northwest China, is one of the friction--melt-derived tectonites by the rapid faulting of ancient seismic zone , which is testified by the characteristics of microstructure, e. g. the presence of glassy pseudotachylites and differently morphological microlites, such as skeletal, dendritic, acicular and globular in the matrix of pseudotachylites. The bulk ages of both K-Ar and ^40Ar/^39Ar step-heating of the pseudotachylite matrix yielded 282.8±3.8 Ma and 276.4±7.4Ma, respectively; and the ages of U-Pb of zircons from the two granitoids being the wall rocks of the pseudotachylite are 390.4±1.0 Ma and 396.3± 0.7 Ma, respectively. These results show that the pseudotachylites from the Keketuohai--Ertai fault zone formed in the early Permian period , and the occurrences of pseudotachylite may probably indicate the most earliest paleoseismic event during the early Permian times along the Keketuohai--Ertai fault zone. The Fuyun magnitude 8.0 earthquake in 1931 is just one of the multi-seismic activities along the Keketuohai-- Ertai fault zone, which has no any genetic relationship with the pseudotachylites developed in the fault.

关 键 词：^40Ar-^39Ar阶段升温 K—Ar年代学 假玄武玻璃 可可托海-二台断裂带 新疆 

分 类 号：P597.3[天文地球—地球化学]