论兰坪盆地白秧坪铜(钴)矿床成因的氦氩同位素证据  

A Discussion on the Helium and Argon Isotopic Evidences for Genesis of the Baiyangping Copper—Cobalt Deposit in the Lanping Basin

作　　者：范世家[1] 王安建[2] 刘汉斌[3] 修群业[3] 曹殿华[1] 李瑞萍[1] 高辉[1] 陈其慎[4] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质科学院,北京100037 [3]核工业北京地质研究院,北京100029 [4]中国地质大学,北京100083

出　　处：《地质论评》2006年第5期628-635,共8页Geological Review

基　　金：科技部973项目(编号2002CB412607)的成果。

摘　　要：对兰坪盆地白秧坪铜钴矿床围岩及流体包裹体的研究揭示,蚀变围岩中存在锂元素的高浓集异常,相对于上地壳值(20×10-6)平均富集系数为14.55;在成矿早阶段(主成矿阶段)的流体包裹体中,Li+的含量占阳离子总量的20%以上;在假定锂的丰度同地壳一致的前提下,前人依据白秧坪铜钴矿床矿物流体包裹体中He和Ar同位素值,得出成矿流体中有幔源氦加入的结论。但由于核反应6Li(n,α)3He的存在,其3He/4He值异常于正常地壳值的原因是由于矿区存在锂的元素高浓集。故笔者认为,尚无确切证据推断白秧坪铜钴矿床成矿流体中及成矿过程中有幔源氦的参与。In Baiyangping copper cobalt deposits, the lithium concentration in altered rock is 14.55 times by the lithium abundance （20X 10^-4）of Upper Crust. In the fluid inclusion of main ore-forming stage, the concentration of Li^＋ is more than 20%o of total cations. It is obvious that there is an enrichment of Lithium in Baiyangping copper cobalt deposits. The former conclusion that there is a mix of helium components between crust and mantle by the values of helium and argon isotope is based on the presupposition that the lithium abundance in Baiyangping copper cobalt deposits is the same as that in normal crust. Lithium-rich crustal rocks can be an important source of 3He due to the nucleogenic reaction：^6Li（n,a）→^3He. The ^3He/^4He ratios may be elevated by the high concentration of lithium, so there are not confirmed evidences to concluded that the mantle fluids had engaged in the fluid activities and mineralizations in the Baiyangping copper-cobalt deposits.

关 键 词：幔源流体 氦同位素 锂元素丰度 白秧坪 兰坪盆地 

分 类 号：P618.41[天文地球—矿床学]