海南岛中部五指山地区早白垩世火山岩地球化学特征及其形成构造背景  

Geochemistry and tectonic setting of the Early Cretaceous volcanics in Wuzhishan area,Hainan Island,South China

作　　者：林义华[1] 吕昭英[1] 袁勤敏[1] 王超[1] 官军[1] 胡在龙 

机构地区：[1]海南省地质调查院,海口570206

出　　处：《华南地质与矿产》2017年第3期215-228,共14页Geology and Mineral Resources of South China

基　　金：中国地调局区域地质调查项目"海南省1:5万番阳;五指山;营盘村;乘坡幅区域地质调查"(1212011120820)

摘　　要：海南岛中部五指山地区发育一套中酸性向酸性演化的火山岩系,总厚度>2 299 m,岩性自下而上主要由英安质—流纹质熔岩及相应的火山碎屑岩组成,在TAS火山岩分类图上大部分落入流纹岩区,仅个别落入英安岩、玄武安山岩、粗面安山岩区。岩石具有Si O2、Al2O3、Na2O、K2O偏高,而Ca O、Mg O、Ti O2等偏低的特点。稀土配分模式均表现为呈右倾的轻稀土富集型曲线,轻、重稀土分异较强,LREE/HREE=10.17~22.34(平均13.56)。岩石富集大离子亲石元素,亏损高场强元素,具有正常弧花岗岩浆的特点,推断其形成于伸展的大地构造背景。A suite of lavas thickness more than 2299 m exposed in Wuzhishan area, Mid-Hainan Island. Which lavas mainly consisted with dacitic-rhyolitic lava and pyroclastic rocks. In TAS diagrams of volcanic rocks,most of the examples fall into the rhyolite area,only several of them fall in the dacite, basaltic andesite and trachyandesite areas. The rocks have relatively high SiO2,Al2O3,Na2O and K2O and low CaO、MgO and TiO2. The REE pattern of the lavas shows right-dipping trend which indicates LREE enriched, LREE/HREE=10.17-22.34（mean13.56）. The lavas also have characteristics of enrichment of LILE and depletion of HFSE. All the features indicate the lavas have similar characteristicsof normal arc granite magma, these rocks must have been formed under the extensional tectonic setting.

关 键 词：火山岩 地球化学 构造环境 五指山地区 海南中部 

分 类 号：P581[天文地球—岩石学]