摘要
西秦岭天水地区分布有新生代陆相酸性火山岩 ,主要由流纹岩、流纹质角砾凝灰熔岩、流纹质熔结 (角砾 )凝灰岩及少量角砾凝灰岩、火山角砾岩等组成 ,具有富硅、富碱、低铝、低钙特征 ,属于非造山偏碱性岩石 ,类似于大陆裂谷碱性流纹岩。研究表明 ,新生代陆相酸性火山岩为地壳岩石部分熔融作用的产物 ,形成于陆内拉张构造环境 ,与新生代早期渭河断裂带的左行走滑剪切构造作用有关。
There occur Cenozoic continental acid volcanic rocks in Tianshui area, West Qinling Mountains. They are composed mainly of rhyolite and partly of rhyolitic breccia tuffaceous lava as well as rhyolitic ignimbrite (breccia) tuff, together with a small amount of breccia tuff and volcanic breccia. These volcanic rocks are geochemically characterized by Si-, alkali-enrichment and Al-, Ca-depletion and belong to nonorogenic alkaline rocks, similar to continental rift type alkaline rhyolite. New evidence shows that Cenozoic acid volcanic rocks were formed by partial melting of crustal rocks in a continental extension setting, related to sinistral strike-slip shearing of Weihe faulted zone in early Cenozoic.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2004年第3期227-235,共9页
Acta Petrologica et Mineralogica
基金
国家自然科学基金重点资助项目 ( 4 0 2 3 40 41)
教育部科学技术研究重点资助项目 ( 10 4175 )
中国地质调查局地质调查资助项目 ( 2 0 0 0 13 0 0 0 15 4)
国土资源部"十五"科技资助项目 ( 2 0 0 10 2 0 1)
关键词
酸性火山岩
地球化学
新生代
天水地区
西秦岭
acid volcanic rocks
geochemistry
Cenozoic
Tianshui area
West Qinling Mountains
