滇西福贡亚五夺透闪玉矿物学特征及成因  

The gemological characteristics and genesis of the Yawuduo tremolite nephrite deposits in Fugong county,western Yunnan province,China

作　　者：廖程[1] 薛传东[1] 唐靓[1] 杨志超[1] LIAO Cheng XUE Chuandong TANG Jing YANG Zhichao

机构地区：[1]昆明理工大学地球科学系,昆明650093

出　　处：《地质找矿论丛》2017年第2期236-244,共9页Contributions to Geology and Mineral Resources Research

基　　金：国家自然科学基金项目(编号:40772067;编号:41373049);中国地质调查局地质调查项目(编号:12120114064302;编号:1212011220908);教育部基金项目(编号:20125314110006)联合资助

摘　　要：在滇西福贡亚五夺地区普遍发育有规模不等的透闪石玉矿(化)体,呈不规则大脉状产于片麻岩、片岩的大理岩夹层与糜棱岩化花岗岩的接触部位。本文在系统调查矿床(体)地质的基础上,采用化学分析、粉晶X衍射及能谱分析等方法,研究了区内透辉石玉的宝石学、矿物学特征,进而对其成因进行探讨。透闪石玉矿石折射率1.60,硬度5.6,密度2.9g/cm^3±,达到玉石品质的指标要求,可作为一种新类型的软玉矿床开发;其主要矿物组成(体积分数)为透闪石(45%)、透辉石(40%),并含方解石(5%)、石英(5%),以及少量的长石、石榴石、磷灰石、榍石、独居石等;透闪石的SiO_2、CaO、MgO含量(质量分数)分别54.54%、22.32%、18.62%,并有少量的Fe_2O_3、Na_2O、Al_2O_3,其晶胞参数a0、b0、c0及β分别为0.978×10^(-10) m、1.785×10^(-10) m、5.284×10^(-10) m及104.45°。结合矿床地质特征以及矿石与围岩稀土元素示踪分析,该透闪石玉矿床仍属变质热液型矿床,但其是在区域性同岩浆同变形时期的拉张阶段,变质流体混合岩浆残余热液沿裂隙充填而成的,应是一种新的矿床成因类型。其成矿时期与碧罗雪山—崇山变形带喜马拉雅中晚期大规模的走滑剪切作用相关大体时限为22~15Ma。本区域具有同等地质背景和成矿条件的地段范围巨大,具有很大的找矿前景。In Yawuduo area,Fugong county,western Yunnan province occur widely different sized irregular nephrite dykes at,contact zone between mylonitized granite and marble intercalations of gneiss and schist.The results of microscopic observation,X-ray diffraction spectra and energy dispersion spectra and chemical analysis of the nephrite samples show that the refractive index is 1.60,hardness 5.6,and density about 2.9g/cm^3.The data meet requirements of jade and they can be served as one new type of the jade to exploit.The mineral volumetric measurement of the Yawuduo nephrite is tremolite(45%),diopside(40%),and calcite(5%),quartz(5%),and minor feldspar,garnet,apatite,sphene,monazite,etc.Percentage(mass fraction)of SiO_2,CaO and MgO in tremolite is 54.54%,22.32% and 18.62%reapectively.Fe_2O_3,Na2 O and Al_2O_3 are in minor amount.Crystal cell parameters,a0、b0、c0andβof tremolite are 0.978×10^(-10) m、1.785×10^(-10) m、5.284×10^(-10) m 及 104.45°respectively.The geological characteristics of the deposit and tracing analysis of REE of the wall rock reveal that the nephrite deposit is still a metamorphic hydrothermal deposit.However,it is formed by fissure filling of mixture of metamorphic fluid and residual magmatic fluid during regional synmagma,syndeformation-tensile extension thus should be a new genetic type of nephrite deposit.The mineralization is related to large-scale strikeslip shearing of Biluoxueshan-Chongshan shear zone and timely limited by Late Himalayan orogeny,about22~15 Ma.The same geological setting and mineralization condition as the deposit is in huge area and is of great potential for prospecting.

关 键 词：透闪石玉 矿物学特征 粉晶X衍射 能谱分析 云南省 

分 类 号：P578.955[天文地球—矿物学] P619.281[天文地球—地质学]