西藏雄巴—德来地区古近纪火山岩相及火山机构

Volcanic Facies and Volcanic Edifice in Paleogene Period at Xiongba-Delai District,Tibet

西藏雄巴—德来地区构造上处于冈底斯—下察隅晚燕山—喜马拉雅期火山岩浆弧带中段,火山活动强烈。分布于冈底斯山雄巴、马雄、德来一线的火山岩,为冈底斯火山岩浆弧的主要组成部分,形成于古新世—始新世。属隆格尔—南木林地层分区的林子宗群火山岩,根据火山喷发旋回,地层由下到上可以划分为典中组、年波组和帕那组,岩石类型以中酸性凝灰岩为主,次为安山岩、流纹岩、英安岩,少量玄武岩。火山岩相可分为爆发相、溢流相和火山沉积相,具中心式火山机构特征。在古近纪喜马拉雅陆块与冈底斯陆块碰撞过程中,南特提斯洋壳俯冲消减期的岩浆活动,形成了本区广为分布的陆缘岛弧型火山岩。

Volcanic facies,which have the characteristics of central volcanic edifice,can divided into explosive facies,extrusive facies and volcanic deposit facies.It is magma activity in South Tethyan oceanic crust subduction period in the collision process between Himalayan and Gangdese landmass.So the continental marginal arc volcanic rock was formed in Xiongba-Delai district,Tibet.