柴达木盆地北缘宗务隆构造带早古生代锆石SHRIMP年龄的测定及其地质意义  

Determination of Early Cambrian Zircon SHRIMP U-Pb Datings in Zongwulong Tectonic Belt,Northern Margin of Qaidam Basin,and Its Geological Significance

作　　者：孙娇鹏 陈世悦[1] 彭渊[2] 邵鹏程 马帅 刘金 

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中国地质科学院地质力学所,北京100081

出　　处：《地质论评》2015年第4期743-751,共9页Geological Review

基　　金：国土资源地调项目(资[2014]03-025-002;12120113040000-3)的成果

摘　　要：取自柴达木盆地北缘宗务隆构造带的5个变质岩样品、80颗锆石SHRIMP U-Pb测年结果表明：80颗岩浆成因锆石年龄分布在510-420Ma之间;5个测试样品的^206Pb/^238U平均年龄分别为437.8±2.7Ma（样品Qb-217）、440±3Ma（样品Qb-218）、433.2±3.6Ma（样品Qb-219）、497.1±3.5Ma（样品Qb-225）、464.1±4.2Ma（样品Qb-228）,这5组^206Pb/^238U平均年龄均代表了锆石结晶年龄,即岩浆侵位年龄。加里东期锆石的大量存在说明宗务隆构造带早古生代存在与板块离散—聚合有关的岩浆活动,是介于中—南祁连地块与欧龙布鲁克地块之间的板块边界。宗务隆构造带是一条经历了漫长地质演化过程和多期造山运动的多旋回复合造山带,构造雏形形成的起始时限不晚于497.1±3.5Ma,构造格局奠定于海西—早印支期。这是对宗务隆带研究的突破,在该区域地质演化中具有重要意义。Based on the zircon SHRIMP U-Pb analysis on 5 metamorphic rock samples collected from the Zongwulong tectonic belt,Northern Margin of Qaidam Basin,80 magmatic zircon age dating results distribute from510 Ma to 420 Ma. The 5 tested samples yield ^206Pb/^238U average ages of 437. 8 ± 2. 7Ma（ sample Qb-217）,440 ±3Ma（ sample Qb-218）,433. 2 ± 3. 6Ma（ sample Qb-219）,497. 1 ± 3. 5 Ma（ sample Qb-225） and 464. 1 ± 4. 2Ma（ sample Qb-228）,respectively,after corrected by204 Pb. These five ^206Pb/^238U average ages indicate the time of zircon crystallization and the enplacement time of the magma. The proliferation of Caledonia zircons shows that,magmatic and metamorphic activities related to massif discrete—aggregation existed during the Early Paleozoic period. The Zongwulong tectonic belt is a massif boundary between Central—South Qilian massif and Oulongbuluke massif. Thereby,Zongwulong tectonic belt is a composite orogeny with long term geological evolution processes and multi-phased tectonic events. Its structural rudiment formed no later than 497. 1 ± 3. 5 Ma. Its tectonic framework established eventually in the Indo—Chinese period.

关 键 词：柴达木盆地北缘 宗务隆构造带 宗务隆群 早古生代 锆石SHRIMP U-PB年龄 

分 类 号：P597.3[天文地球—地球化学] P548[天文地球—地质学]