摘要
西天山火山岩属玄武安山流纹岩建造,钙碱性(中钾、高钾)和橄榄玄粗岩系列。其40Ar/39Ar年龄范围为250～306Ma,以260～290Ma为高峰值。浅侵位岩浆岩属偏碱性、碱性岩石或高钾钙碱性系列岩石,40Ar/39Ar年龄范围为260～290Ma。综合Ar-Ar和Rb-Sr、U-Pb年龄资料,西天山地区火山-浅侵位岩浆活动高峰期发生在晚石炭世—早二叠世。40Ar/39Ar坪年龄资料还显示了晚二叠世、侏罗纪—早白垩世的热事件信息。对区内高钾钙碱性火山岩、橄榄玄粗岩和埃达克质岩石等富碱火成岩的年龄测定表明,本区构造格架的重大转折———由俯冲、碰撞造山的挤压,转向后碰撞的伸展、拉张———发生在石炭纪末—早二叠世(250～300Ma)期间。
Volcanic rocks in western Tianshan belong to basalt andesite rhyolite series, or medium potassic calc alkaline, high potassic calc alkaline and shoshonitic series. The range of 40Ar/39Ar ages of the volcanic rocks is 250～ 306 Ma with peak values of 260～ 290 Ma. The hypabyssal igneous rocks belong to subalkaline alkaline or high potassic calc alkaline series. Their 40Ar/39Ar ages are from 260 Ma to 290 Ma. These 40Ar/39Ar ages have shown that the volcanic hypabyssal magmatic activities happened during late Carboniferous to early Permian, and mainly at the end of late Carboniferous to early Permian. According to the data of 40Ar/39Ar dating several thermal events may take place in late Permian, and Jurassic to early Cretaceous. The 40Ar/39Ar chronological data of high potassic calc alkaline series, shoshonitic series and adakite alkali rich igneous rocks have shown that in the orogeny process of western Tianshan the tectonic framework transformed from the compression of subduction and collision orogeny to the extension of post collision during the end of Caboniferous to early Permian (250～ 300 Ma).
出处
《地球化学》
CAS
CSCD
北大核心
2003年第4期317-327,共11页
Geochimica
基金
国家重点基础研究计划(2001CB409803)
国家"305"项目(96-915-03-02)
国家攀登计划预选项目(95-预-25)
