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马达加斯加南部Tranomaro地区钍矿石中发现了自然界中极为罕见的钙柱石(Me=87.8%~99.2%),钙柱石主要产于Anosyan花岗岩体(主要为紫苏花岗岩)与碳酸盐岩接触部位所形成的钙质夕卡岩和大理岩中,与透辉石、石榴石、橄榄石、硅灰石、金云母、钙长石、方解石和角闪石等共生。化学分析显示,除Si O2、Al2O、Ca O和Na2O等主要组分(w(Si O2)=40.95%~43.91%,w(Al2O3)=29.48%~36.10%,w(Ca O)=19.23%~21.86%,w(Na2O)=0.30%~1.60%)外,钙柱石中还含有CO2-3、F-、Cl-和SO3等。钙柱石的合成实验及矿物学研究表明,该地区钙柱石是在温度大于850℃,压力300~500 MPa条件下,且富含CO2和Ca2+的地质环境中形成。钍矿石中钙柱石的发现表明:方钍石等钍矿物形成的温度超过850℃,形成深度约为9.9~16.5 km;与钍成矿有关的流体是超临界的气-液流体;流体中富含的F和CO2等组分对该地区钍成矿起着决定性的作用。
Found in the Thorium ore in the Tranomaro region of southern Madagascar, rare earth beryllium (Me = 87.8% -99.2%) was found in nature and was mainly produced by contact with the Anosyan granitoids (mainly Perillaite) and carbonate rocks Calcareous skarn and marble, and diopside, garnet, olivine, wollastonite, phlogopite, anorthite, calcite and amphibole, and other symbiosis. The chemical analysis showed that the main components (w (Si O2) = 40.95% ~ 43.91%, w (Al2O3) = 29.48% ~ 36.10% and w (CaO) = 19.23% except Si O2, Al2O, CaO and Na2O) ~ 21.86%, w (Na2O) = 0.30% ~ 1.60%), the pyroxene also contains CO2-3, F-, Cl- and SO3. The synthetic experiments and mineralogical studies of the pyroxene show that the propionate is formed in geological environment rich in CO2 and Ca2 + at the temperature of more than 850 ℃ and the pressure of 300 ~ 500 MPa. The results show that the temperature of thorium and other thorium minerals is over 850 ℃ and the depth is about 9.9 ~ 16.5 km. The fluid related to thorium metallogenesis is supercritical gas-liquid fluid. Containing F and CO2 and other components of thorium mineralization in the region plays a decisive role.