峨眉山大火成岩省“高钛玄武岩”和“低钛玄武岩”成因探讨  

Petrogenesis of High-Ti and Low-Ti Basalts from the Emeishan Large Igneous Province

作　　者：郝艳丽[1] 张招崇[1] 王福生[1] John J.MAHONEY 

机构地区：[1]中国地质科学院地质研究所 [2]School of Ocean and Earth Science and Technology,University of Hawaii,Honolulu,HI96822,USA

出　　处：《地质论评》2004年第6期587-592,共6页Geological Review

基　　金：国家自然科学基金项目 (编号 40 2 73 0 2 0 );国家重点基础研究发展规划项目 (编号 G19990 43 2 0 5 );国土资源部优秀青年计划资金资助的成果

摘　　要：大量的岩石化学资料分析表明 ,峨眉山大火成岩省玄武岩的 Ti O2 含量是连续变化的 ,不存在明显的间断。野外地质特征表明高钛和低钛玄武岩既不存在空间分带 ,也不存在时间分带。其 Sr、Nd和 Pb同位素组成也没有明显的区别 ,推测它们可能是同源岩浆分离结晶的产物。根据 Mg O和 Ti O2 的相关关系 ,可将苦橄岩和玄武岩的演化划分为 4个趋势 ,并采用分离结晶模式对其进行了成因模拟 ,表明高钛和低钛玄武岩是同一母岩浆 (苦橄—玄武岩浆 )Analyses of basalts from the Emeishan large igneous province show that the TiO 2 contents of them are variable continuously. And outcrops of high Ti and low Ti basalts in field are unzoned spatiotemporally. The similar Sr, Nd and Pb isotopic compositions of these two types of basalts indicate that they are comagmatic igneous rocks. The MgO versus TiO 2 diagram for picrites and basalts shows four evolution trends, whose geneses were simulated by the fractional crystallization model. The result suggests that high Ti and low Ti basalts are different products of the same parent magma (picritic basaltic magma) through fractional crystallization of different minerals.

关 键 词：玄武岩 峨眉山大火成岩省 成因探讨 分离结晶 PB同位素 空间分带 苦橄岩 母岩 连续变化 含量 

分 类 号：P588.1[天文地球—岩石学]