云南易门铜厂铜矿床碳酸盐矿物微量元素组成研究

易门铜厂矿床是云南易门铜矿带中的一个大-中型铜矿床,矿区存在早期沉积-成岩型和晚期热液脉状型2种铜矿类型。为深入阐明2种矿化类型的成矿作用特征,文章分别选取落雪组白云岩及层状矿石中的白云石和热液脉状矿石中的方解石,采用ICP-MS等方法,对其开展碳酸盐矿物的微量及稀土元素地球化学研究。研究结果显示：在微量元素组成方面,沉积-成岩型的白云石以富集Cu、Pb、Zn、Ba、Bi、Sb、Ga、Ag,亏损Mo、Cr、Ni、Co、V元素为特征,脉状方解石中则以亏损亲硫元素（Cu、Pb、Zn）和不相容元素（Ba、Be、Rb、Nb、Ta、Zr、Hf、Th、U等）,富集V、Co、Ni元素为特征;在稀土元素组成上,二者稀土元素总量均较低,具不同程度的Eu负异常和微弱的Ce正异常,但在稀土元素配分模式上,白云石为明显右倾的轻稀土元素富集模式,方解石则为轻稀土元素略富集,中稀土元素富集的缓右倾或平缓型配分模式。综合分析结果认为,2类脉石矿物是不同成矿系统的产物,白云石形成于正常浅海环境,为沉积-成岩成因,成矿物质的壳源特征明显。方解石为后期热液成因,有深源物质参与成矿。层状矿体与脉状矿体不具"同期+同源"的特征。

Study of trace elements in carbonate minerals of different ores from Tongchang deposit, Yimen,Yunnan

The Tongchang deposit is a medium-large copper deposit in the Yunnan Yimen copper ore belt. There are two types of mineralization including the sedimentary-diagenesis and hydrothermal vein in Tongchang deposit. Geochemical characteristics of rare earth and trace elements in dolomite and calcite from Luoxue Formation were studied with ICP-MS method to further identify the metallogenic characteristics of the two types of mineralization. The results show that in the trace elements composition, the dolomite is enriched in Cu, Pb, Zn, Ba, Bi, Sb, Ga, Ag and depleted in Mo, Cr, Ni, Co, V. The vein-type calcite is enriched in V, Co, Ni, and depleted in chalcophile elements (Cu, Pb, Zn) and incompatible elements (Ba, Be, Rb, Nb, Ta, Zr, Hf, Th, U). In the rare earth elements composition, both have lower total amounts of rare earth elements, with varying degrees of negative Eu anomalies and weak positive Ce anomalies; nevertheless, in the REE patterns, dolomite obviously exhibits right-inclined pattern characterized by enrichment of LREE, calcite is of smoothly right or flat type distribution patterns characterized by slight enrichment of LREE and MREE. Comprehensive analysis indicates that two types of gangue minerals were produced in different metallogenic systems. The dolomite is of sedimentary-diagenesis genesis and was formed in the normal shallow marine environment, with obvious crust source characteristics of metallogenic material. Calcite is of late-hydrothermal genesis, and mineralization involved deep source material. Stratiform ore and vein ore have not the characteristics of "the same period and homologous character".