广西都庞岭地区锡矿床锡石主要、微量及稀土元素的组成特点及赋存状态

COMPOSITIONAL CHARACTERISTICS AND EXISTING FORMS OF MAJOR, TRACE AND RARE-EARTH ELEMENTS IN CASSITERITE IN THE DUPANGLING TIN ORE-FIELD, GUANGXI

对都庞岭地区石英脉型、云英岩型锡矿中锡石主要,微量及稀土元素的研究表明:①锡石中SnO_2与W、Fe_2O_3、Nb、Ta呈显著负相关,与Mn、In,As、REE呈不显著负相关,与Sb无相关;②稀土元素总体分馏不强,主要表现为LREE,尤其是HREE的富集与Eu的相对贫化;③在锡石中W、Mn、Nb、Ta、In、REE类质同象替代Sn,Sc,Fe^(3+)、As也可能以类质同象形式存在,Sb可能以其它形式存在;④与石英脉中锡石相比,云英岩中锡石富REE、Fe_2O_3、W、Mn、Nb、Ta、Sc、In,贫As、Sb,其δEu值和LREE/HREE、Nb/Ta比值较低;⑤锡石的微量元素含量、比值及稀土配分参数可作为找矿标志,并指示隐伏矿床类型。

Studies of major, trace and rare-earth elements in cassiterite in quartz vein- and greisen-type tin deposits in the Dupangling ore field revealed that: (1) in cassiterite SnO_2 negatively correlates with W, Fe_2O_3, Nb, Ta, Mn, In, As, and REE, hut shows no correlation with Sb; (2) on the whole, REE fractionation is not so strong as reflected by LREE (especially HREE) enrichment and relative Eu depletion; (3) in the cassiterite W, Mn, Nb, Ta, In, REE, and possibly Sc, As, enter the lattice in the form of isomorphous substitution for Sn, but Sb exists in other form; (4) compared with cassiterite in quartz veins, the cassiterite in greisens is rich in REE, Fe)2O_3, W, Mn, Nb, Ta, In, and So, but poor in As and Sb, with low δEu value and LREE/ HREE and Nb/Ta ratios; and (5) the contents and ratios of trace elements and REE distribution parameters of cassiterite can be regarded as effective guides for prospecting and as indicators of the type of concealed ore deposits.