福建省中生代双峰式火山岩的特征及成因

基金项目:

地质矿产部1∶5万区域地质调查项目

详细信息

FEATURES AND ORIGIN OF MESOZOIC BIMODAL VOLCANIC ROCKS IN FUJIAN PROVINCE

摘要: 福建省中生代双峰式火山岩分别发育于早侏罗世藩坑组、早白垩世石帽山群，二者在剖面上均表现为流纹质火山岩直接覆盖在玄武岩之上。两个时期的双峰式火山岩均发育于断陷带上的火山构造洼地（盆地）内，形成于活动大陆边缘板内拉张环境。玄武岩是上地幔经１０％～２０％部分熔融形成；流纹质岩浆来源于下地壳经１５％～２３％部分熔融，并有较多地幔物质参与。
Abstract: Mesozoic bimodal volcanic rocks in Fujian province occur in the Early Jurassic Fankeng Formation and Early Cretaceous Shimaoshan Group. In section, the two lithostratigraphic units are marked by rhyolitic rocks overlying basalts directly. The bimodal volcanic rocks of the two epochs are both developed in volcanic depressions （basins） in a downfaulted zone and were formed in an intraplate extensional environment on active continental margins. Basalts originated by 10%～20% of partial melting of the upper mantle; whereas rhyolitic magma was derived by 15%～23% of partial melting of the lower crust. Appreciable amounts of mantle materials were introduced into the rhyolitic magma to form the mantlecrust mixture.
- Mesozoic /
- bimodal volcanic rocks /
- intraplate extensional environment /
- Fujian