四川盐源地区峨眉山玄武岩喷发旋回及意义

Eruption Cycle of Emeishan Basalt and Its Significance in Yanyuan,Sichuan

在四川1∶5万瓜别、大桥、大林、金河、小高山、盐源6幅区调工作工程中,发现峨眉山玄武岩在四川盐源地区分布广泛,出露良好,其主要沿着金河断裂西侧以裂隙式喷发为主。利用此次区调工作的剖面测制成果,分析峨眉山玄武岩在盐源雅砻江至香房乡大岩房一带的喷发旋回及其喷发特征,总结峨眉山玄武岩在区域上的喷发特征,根据火山活动强烈程度及岩浆演化特征可将盐源地区峨眉山玄武岩划分为两个亚旋回,其喷发强度逐渐减弱,岩浆总体由基性向中基性演化。其形成于板内构造环境,时间为二叠纪晚期。

The Emeishan basalt is widely exposed along the western side of the Jinhe fault in Guabie,Daqiao,Jinhe,Xiaogaoshan and Yanyuan regions.This paper has a discussion on eruption cycle and eruption characteristics of the Emeishan basalt in the Yanyuan region.The Emeishan basalt in the Yanyuan region may be divided into two eruption cycles.The intensity of the eruption is decreasing ascendingly.Generally,the magma was evolutional from basic to intermediate-basic.The Emeishan basaltin the Yanyuan region was formed in intraplate setting during the Late Permian.