中国地质2012，Vol.39Issue(5)：1151-1161,11.
西藏南木林县罗扎地区早白垩世流纹岩锆石 U-Pb 年龄及地球化学特征
Zircon U-Pb age and geochemistry of Early Cretaceous rhyolite in Luozha area of Namling County, Tibet
摘要
Abstract
The authors studied the nearly EW —trending volcanic rocks in vast areas of northern Luozha zone along the Gangdise arc—ridge fault—uplift zone, obtained the LA—ICP—MS zircon age of 129.8±1.4 Ma, and proved for the first time the existence of Early Cretaceous volcanic rocks in the Gangdise arc—ridge fault—uplift zone. The volcanic rocks are characterized by high SiO2, K2O and K2O/Na2O values, the enrichment of LILEs (Rb, Ba, Th and U) and the depletion of Nb, Ta and Ti. Their cobweb curve is on the whole the same as that of the upper crust and the acidic volcanic rocks owing to crustal remelting of Zenong Group of the Gangdise zone at 110 Ma. These data indicate that the volcanic rocks might be the remelting products resulting from the dehydration of crustal materials. According to the environmental discrimination diagrams of trace elements, the authors consider that they are arc volcanic rocks. In combination with the tectonic background of Early Cretaceous period, it is thought that they were most likely associated with northward subduction of the Yarlung Zangbo River oceanic crust.关键词
早白垩世/冈底斯弧背断隆带/U-Pb年龄/LA-ICP-MS/流纹岩/锆石Key words
Early Cretaceous/ Gangdise arc—ridge fault—uplift zone/U—Pb age, LA—ICP—MS, rhyolite/zircon分类
天文与地球科学引用本文复制引用
刘伟,李奋其,杨晓勇,袁四化..西藏南木林县罗扎地区早白垩世流纹岩锆石 U-Pb 年龄及地球化学特征[J].中国地质,2012,39(5):1151-1161,11.基金项目
国家自然科学基金项目(41090372)和国土资源大调查项目(1212010818016)联合资助. （41090372）
