甘肃天水地区新生代火山岩地球化学特征及其成因  

GEOCHEMICAL CHARACTERISTICS AND ORIGIN OF CENOZOIC ACID VOLCANIC ROCKS IN THE TIANSHUI AREA, GANSU PROVINCE

作　　者：丁仨平 裴先治[1] 胡波[1] 李勇[1] 郭俊锋[1] 李佐臣[1] 赵欣[1] 

机构地区：[1]长安大学地球科学与国土资源学院

出　　处：《地质与勘探》2005年第1期33-37,共5页Geology and Exploration

基　　金：国家自然科学基金项目(批准号:40234041);教育部科学技术研究重点项目(编号:104175);中国地质调查局地质调查项目(编号:200013000154)联合资助。

摘　　要：西秦岭甘肃天水地区分布的新生代陆相中酸性火山岩,主要由流纹岩、部分流纹质熔结(角砾)凝灰岩及少量角砾凝灰岩、火山集块岩等组成。地球化学特征显示具有富硅、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,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 are Cenozoic continental intermediate and acid volcanic rocks in the Tianshui area, western Qinling. The rocks are mainly composed of rhyolite, parts of rhyolitic ignimbrite (breccia tuff), a little amount of breccia tuff and volcanic agglomerate. These volcanic rocks are geochemically characterized by Si-, alkali-richment and Al-, Ca-depletion and are nonorogenic alkaline rocks, which are similar to continental-rift-type alkaline rhyolite. They are products of partial melting of crustal rocks, formed in continental extension setting and related to sinistral strike-slip shearing of Weihe fault zone in the early stage of Cenozoic.

关 键 词：火山岩 地球化学 新生代天水地区 西秦岭 

分 类 号：P588.14[天文地球—岩石学] P59[天文地球—地质学]