湖南芙蓉锡矿田流体包裹体的He同位素组成及成矿流体来源示踪  

Helium Isotope Composition of Fluid Inclusions and the Origin of Ore-Forming Fluids of Furong Tin Orefield in Hunan Province, China

作　　者：李兆丽[1] 胡瑞忠[1] 彭建堂[1] 毕献武[1] 李晓敏[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学重点实验室

出　　处：《地球科学（中国地质大学学报）》2006年第1期129-135,共7页Earth Science-Journal of China University of Geosciences

基　　金：中科院重要方向项目(Nos.KZCX3-SW-125;KZCX2-101)"西部之光"项目

摘　　要：芙蓉锡矿田位于湖南省骑田岭花岗岩体的南部,是一个新近发现的超大型锡矿田．与以往所研究的与S型花岗岩有关的锡矿床明显不同,这个矿田在时空上都与骑田岭A型花岗岩密切相关．该矿田矿石硫化物流体包裹体的3He／4He测定值为0．14-2．95 Ra,低于地幔的3He／4He值(6-7 Ra),且高于地壳的3He／4He值(0．01-0．05 Ra)．这表明芙蓉锡矿田成矿流体中的He具壳幔两端元混合的特点．该区一致的硫、锶及其他证据也都表明,深部地幔物质确实参与了该区锡的成矿．骑田岭岩体属造山期后张性环境下形成的A型花岗岩类．芙蓉锡矿田就产在骑田岭岩体的内外接触带或岩体中,其主成矿期与骑田岭岩体的形成时间相当吻合,且两者均具壳幔两端元混合成因的特征,所以其形成地球动力学背景可能均与中生代华南岩石圈的拉张、伸展作用密切相关．The Furong tin orefield, located in southern Hunan, China, is a newly-discovered super-large tm orefield, in contrast to most other tin deposits associated with S-type granites, the Furong tin deposit is spatially and temporally associated with the Qitianling A-type granite. The ^3He/^4 He ratios of fluid inclusions in sulfides from this orefield range from 0. 14 to 2.95 Ra, which are lower than that of the mantle, and higher than that of the crust, indicating that the helium in ore forming fluids from this orefield is a mixture of two end-member components, mantle-source He and crust-source He. This conclusion is in accordance with the S isotope, Sr isotope and other results, suggesting that there must be some mantle source substance in mineralization of this orefield. The Qitianling granite belongs to A-type granite which formed in a postorogenic extensional settings. The Furong tin orefield is located at the contact zone （outer or inner） or within of Qitianling granite, and its main tin-mineralization time is consistent with the intrusion time of Qitianling granite. The relationship reflects that their forming settings of geodynamics might both be related to the Mesozoic lithospheric extension in South China.

关 键 词：芙蓉锡矿田 成矿流体 HE同位素 

分 类 号：P618.44[天文地球—矿床学] P594[天文地球—地质学]