湘南上堡花岗岩中电气石LA-MC-ICPMS原位微区硼同位素分析及地质意义  

LA-MC-ICPMS in-situ boron isotope analyses of tourmalines from the Shangbao granites (southern Hunan Province) and its geological significance

作　　者：郭海锋[1,2] 夏小平[1] 韦刚健[1] 王强[1] 赵振华[1] 黄小龙[1] 张海祥[1] 袁超[1] 李武显[1] 

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《地球化学》2014年第1期11-19,共9页Geochimica

基　　金：国家自然科学基金(41025006;41073029;41121002);国家重点基础研究发展计划项目(2012CB416703)

摘　　要：电气石的LA—MC—ICPMS原位微区硼同位素分析方法是最近几年新兴的一种高效经济的硼同位素分析方法。对上堡晚白垩世含电气石二云母花岗岩的电气石进行LA—MC—ICPMS原位微区的硼同位素研究发现，其具有非常均一的¨B／mB比值（3．9908～3．9979）~H万¨B值（加权平均为（一12．86＋0．19）‰）。结合区域地质资料以及其他已有的硼同位素资料，提出上堡花岗岩中硼来源于沉积岩，可能的源区是邻近花岗岩体的石炭一二叠系的沉积地层或深埋在地壳中的沉积物质。在晚白垩世，华南处于伸展的背景中，幔源岩浆的底侵带来的巨大的热源使地壳中的沉积物质发生熔融，形成强过铝质的花岗质浆，在岩浆演化的晚期形成电气石。LA-MC-ICPMS tourmaline in-situ boron （B） isotope analysis method, which is very efficient and economic, was newly established in recent few years. The LA-MC-ICPMS tourmaline in-situ B isotope analyses for the Shangbao tourmaline-bearing two mica granites exhibit that these tourmalines have very constant 11B/10B ratios （3.9908-3.9979） and δ11B values （Mean= （-12.86±0.19）‰）. Combined with regional geological data and other previous boron isotope data, we infer that the B element of the Shangbao granites was probably derived from sedimentary rocks, and a possible source was the Carboniferous or Permian sedimentary strata which is near to the Shangbao pluton, or sedimentary materials which were deeply buried in the crust. During Late Cretaceous, as the whole South China Block was under an extensional setting, the underplating mantle-derived magmas heated the overlying sedimentary materials, resulting in their partial melting and the generation of strongly peraluminous magmas. The tourmaline crystallized during the late stage of the evolution of these magmas.

关 键 词：LA—MC—ICPMS 原位硼同位素 电气石 上堡花岗岩 华南 

分 类 号：P597[天文地球—地球化学]