陕西省华阳川铀铌铅矿床碳酸岩岩石学及地球化学特征
Petrologic and Geochemical Characteristics of Carbonatites in Huayangchuan UNbPb Deposit, Shaanxi Province

摘要： 陕西省华阳川铀铌铅矿床是小秦岭成矿带中成矿特征最为独特的矿床，碳酸岩脉的破碎带是重要的成矿空间。未矿化的碳酸岩中矿物以方解石为主，其他矿物很少；发育铀矿化的碳酸岩脉中矿物种类繁多，大部分为方解石，其次为角闪石、金云母、榍石、褐帘石、铌钛铀矿、重晶石、磷灰石、石英、磁铁矿、碱性长石等矿物。碳酸岩的LREE含量异常高，δ13CV-PDB和δ18OV-SMOW值显示典型的火成碳酸岩特征。基于碳酸岩脉的Sr、Nd、Pb同位素比值(87Sr/86Sr-206Pb/204Pb、207Pb/204Pb-206Pb/204Pb-143Nd/144Nd-87Sr/86Sr)的关系图，初步判断华阳川铀铌铅碳酸岩脉是源于EMI的碱性硅酸盐-碳酸盐熔体-溶液结晶分异的产物。
Abstract: The Huayangchuan UNbPb deposit is a unique metallogenic type in the Xiaoqinling mineralization belt. The broken belt of carbonatite vein is important oreforming space. The minerals in unmineralized carbonatites are mainly calcite, and there are few other minerals. Uranium mineralized carbonatites include a variety of minerals, major minerals of which are calcite; and minor minerals of which are amphibole, biotite,sphene,allanite,batafite,barite,apatite,quartz,magnetite,alkali feldspar. Carbonatites are characterized by high REE contents, whose δ13CV-PDB and δ18OV-SMOW values show the typical characteristics of igneous carbonatite. Based on the diagrams showing 87Sr/86Sr vs. 206Pb/204Pb, 207Pb/204Pb vs. 206Pb/204Pb and 143Nd/144Nd vs. 87Sr/86Sr of carbonatite veins, the authors consider that these carbonatite veins are crystalfractionational products of alkaline silicatecarbonate meltsolution originated from the EMI