赞比亚卢姆瓦纳铜矿地质特征及成因

赞比亚卢姆瓦纳铜矿位于世界第三大铜矿带卢弗里安弧形褶皱带西南端,产于姆万比兹穹隆中,穹隆中心出露的最老岩层为基底杂岩,主要为花岗片麻岩、花岗混合岩、互层状长石片岩、长石片麻岩、白云母片岩,铜矿化产于强烈变质、重结晶的白云母-金云母-石英-蓝晶石片岩中,矿石矿物主要为黄铜矿、斑铜矿等硫化物,呈浸染状分布,受片理控制明显。该铜矿包括两个主要铜矿体:马伦德威和齐米乌戈矿体,其中马伦德威矿规模较小,为单层矿化,但是铜品位高,断续见有铀矿化和金矿化,偶尔见钴矿化;齐米乌戈矿体规模较大,可见到3层矿化,但是铜品位低,普遍含钴,偶见少量铀矿。通过对区域地质背景、矿床地质特征分析,认为该区成矿过程大致经历了初始富集、变质成矿和次生富集3个阶段,矿床成因类型为火山喷发—沉积变质型铜矿床。其矿化特征、矿床成因与赞比亚砂页岩型铜钴矿有明显的差异,为在赞比亚找矿开拓了新的找矿方向。

Geological characteristics and gensis of Lumwana copper deposits in Zambia

Lumwana copper deposit of Zambia is located at southwest tip of the Lufilian arc-like fold belt which is the third-largest copper belt in the world.It is hosted within the Mwombezhi dome.The oldest rocks appeared in the center of the dome are basement complexes mainly consist of granitic gneiss, granitic migmatites,interbedded feldspar schist, feldspar gneiss, muscovite schist.The copper mineralization exists within the intensely metamorphosed and recrystallised muscovite-phlogopite-quartz-kyanite schists.The ore minerals are dominated by some sulphides, including the disseminatedchalcopyrite and bornite.The mineralization is apparently controlled by cleavage. Lumwana copper deposit contains two major copper orebodies:Malundwe and Chimiwungo copper orebodies.Malundwe is smaller and has a single-layer mineralization,but it has higher copper grade with discrete uranium and gold mineralizations and sporadic cobalt mineralizaiton. Chimiwungo is a much larger orebody consists of a package of three copper mineralization layers with lower copper grade,but it contains a number of significant high grade cobalt zones as well as some uranium mineralization.Through analysis on the regional geological background and the geological characteristics of the deposit, it is considered in this paper that the mineralization process in this area had undergone three stages:initial enrichment, metamorphic mineralization and secondary enrichment.Genetic type of the copper deposit is a volcanic eruption-sedimentary metamorphic deposit.The characteristics of mineralization in this deposit and its gensis are apparently different from those of the sandy shale Cu-Co deposits in Zambia. Therefore, this paper explored a new direction for mineralsprospectingin the study area.