湖南省毛湾矿区蚀变岩体型钨矿地球化学特征与成矿关系

毛湾矿区出露的岩体属川口岩体的一部分,岩性为二云母二长花岗岩,高硅、中碱,SiO_2和K_2O含量分别平均为74.72%和4.33%,Na_2O+K_2O平均为8.11%,K_2O/Na_2O平均为1.18%,Al_2O_3平均为13.28%,总体属过铝质钙碱性花岗岩类。Ba、Sr等元素表现为强烈的亏损,Mn表现为弱亏损;而Nb、Ta、Sb、W、Mo、Bi、Sn等相对富集,∑REE平均77.22×10~(-6),(La/Yb)N平均为2.67,LREE/HREE平均为2.92,δEu值平均为0.16,显示出岩体从早到晚具有中酸性向酸碱性演化的明显特征,轻重稀土比值有逐渐降低的趋势,表明其挥发组分含量由少到多的演化规律,对探索成矿花岗岩形成的物质来源、岩浆演化机制具有一定意义。

Relationship between geochemical characteristics and mineralization of altered rock mass type tungsten deposits in Maowan mining area of Hunan

Outcropped rock mass of Maowan mining area is a part of Chuankou rock mass,and it is dimica-ceous monzonitic granite with rich silicon and medium alkali.The content of SiO2 and K2 O are 74.72% and 4.33% respectively while the mean value of Na2 O+K2 O,K2 O/Na2 O and Al2 O3 are 8.11%,1.18% and 13.28% respectively,and it suggests that on the whole the rock mass is peraluminous calc-alkali granitoid. Elements like Ba and Sr show intensive depletion,and Mn shows weak depletion,while elements like Nb, Ta,Sb,W,Mo,Bi and Sn show relative enrichment with average ∑REE of 77.22×10-6 and average (La/Yb)N of 2.67 and average LREE/HREE ratio of 2.92 and averageδEu value of 0.16.The data indicates that the rock mass has a clear evolution trend which changes from intermediate acidity to acidity and basicity a-long the timeline,and the gradually decreasing LREE/HREE ratio suggests that the volatile components va-ry from less to more as an evolutionary regularity,and the conclusions have implications for the study of ma-terial source and magmatic evolutionary mechanism of metallogenic granite formation.