阿尔泰地区中、新生代岩浆活动的同位素年龄证据

长期以来，对阿尔泰地区有无印支、燕山期岩浆活动一直存在争议。本研究得到以下年龄结果：将军山花岗岩（＾４０Ａｒ／＾３９Ａｒ坪年龄）２２０Ｍａ、康布铁堡花岗岩（＾４０Ａｒ／＾３９Ａｒ高温视年龄）２１４Ｍａ、尚可兰花岗岩（Ｒｂ－Ｓｒ全岩等时线年龄）１７６Ｍａ、阿拉尔花岗岩（＾４０Ａｒ／＾３９Ａｒ坪年龄）１３１Ｍａ。以上数据和与本区处在同一构造单元的前苏联矿区阿尔泰及山区阿尔泰１２个浅色花岗岩锆石Ｕ－Ｐｂ

EVIDENCE FROM ISOTOPIC AGE FOR PRESENCE OF MESOZOIC-CENOZOIC MAGMATIC ACTIVITIES IN ALTAI REGION,XINJIANG

The debate on the presence of Indosinian-Yanshanian magmatism in the Altai region has continued for a long time. This study obtained significant isotopic ages as following: 220 Ma (40Ar/39Ar plateau age) for Jiangjunshan granite, 214Ma (40Ar 39Ar apparent age at high temperature) for Kangbutiebao granite, 176Ma (Wholerock Rb-Sr isochron age) for Shankelan granite, and 131 Ma (40Ar/39Ar plateau age) for Altai granite. These age data are consistent with those (Zircon U-Pb ages, 180 -200Ma) of the leucocratic granites from the Mining Altai and Mountainous Altai of the former Soviet Union, which are located in the same tectonic unit as the studied region. These favor the presence of Indosinian-Yanshanian magmatism. In addition,Neogene volcanic activities were also identified through isotopic dating of the Halaqiaola basalt, which has an age of 18 Ma (40Ar/39Ar age).