阿合塔拉铜矿床石榴石特征的研究

Study on the characteristics of garnets in Ahetala copper deposit

阿合塔拉铜矿位于新疆柯尔克孜自治州阿合奇县,大地构造位置上处于塔里木板块北缘。本文通过野外地质勘查,室内显微镜观察及电子探针分析,对阿合塔拉铜矿中矽卡岩矿物石榴石进行了较为详细、系统的研究。结果表明,矿床中产出的石榴石分为早晚两期。早期石榴石为钙铝榴石,与透辉石、硅灰石等无水矿物共生,端元组分为钙铝榴石(58.24%~74.61%)—钙铁榴石(22.60%~38.50%)。晚期的石榴石为钙铁榴石,均有明显的生长环带,环带中常包裹磁铁矿,端元组分为钙铁榴石(52.90%~98.79%)—钙铝榴石(0.23%~44.66%)。石榴石边部TFeO含量比核部更高,表明在石榴石形成的过程中,铁质逐渐增加。石榴石颗粒之间被铁铜硫化物充填,表明石榴石的形成先于铜铁矿物的形成,并为铁铜硫化物的产出提供了成矿空间。

The Ahetala copper deposit is located in Arheqi county,kirgiz autonomous prefecture,Xin Jiang. In the geotectonic position,it is located in the northern margin of Tarim. In this article,by using field geological exploration,microscope observation and the electron probe micro analysis（ EPMA）,we studied the skarn mineral garnets. The results of the experiments show that garnets in Ahetala copper deposit are divided into two periods. Early garnets are mainly grossular which is often symbiotic with anhydrous minerals such as wollastonite and diopside. The end member is Grossular（ 58. 24%-74. 61%）-Andradite（ 22. 60%-38. 50%）. In the later stage,garnets are mainly andradite. The garnets of later stage all have clear growth zonings. The growth zonings of garnets are often wrapped in magnetite. Chalcopyrite and bornite usually fill between garnet granules. The end member is Andradite（ 52. 90%-98. 79%）-Grossular（ 0. 23%-44. 66%）. From the core to the rim,both the content of TFe O and the end member of andradite are increasing. It is shown that during the formation of garnets,the iron gradually increases. The iron-copper sulfides,such as chalcopyrite and bornite usually fill between garnet granules. It indicates that the formation of garnets is prior to the formation of copper-iron ores,which provides the mineralization space for the production of iron-copper sulphides.