柬埔寨柏威夏省罗文铁矿床地质特征及成因浅析

Geological Characteristics and Genesis of Luowen Iron Deposit in Preah Vihear of Cambodia

罗文铁矿位于柬埔寨北部柏威夏省罗文县境内,区域上位于罗文真基底穹窿中部,是柬埔寨铁矿产资源的重要产地。该矿区燕山期中酸性岩浆喷发-侵入活动强烈,原生矿体主要呈似层状、透镜状、脉状、囊状产于安山岩、闪长玢岩、凝灰岩等火山岩中,大部分赋矿围岩蚀变发育,主要有矽卡岩化、绿泥石化、绿帘石化、硅化、黑云母化、碳酸盐化等。通过对矿石组构、矿物共生组合、围岩蚀变特征分析,该矿床形成划分为岩浆期和热液期2个成矿期,进一步分为3个成矿阶段:透辉石-石榴子石-磁铁矿阶段、透辉石-石榴子石-透闪石-绿泥石-磁铁矿阶段、黄铁矿(黄铜矿)-镜铁矿-碳酸盐矿物阶段。笔者在野外地质调查和室内分析研究的基础上,认为罗文铁矿矿床成因与火山-次火山岩及其热液活动有关,成矿主要受火山机构尤其是火山口、火山颈相控制,属火山-次火山岩型铁矿床。

Luowen iron deposit is located in Luowen county of Preah Vihear, northern Cambodia. Located in the center of Luowen basement vault, the deposit is an important origin of Cambodia iron mineral resources. The eruption and intrusion activity of intermediate-acidic magma is strong in Yanshanian. The primary ore bodies mainly present as banding, lensing, vein, cystic, and are hosted by volcanic rock which contains andesite, diorite porphyrite and tuff. Alterations such as skarnization, chloritization, epidotization, silicification, biotitization and carbonatization strongly occur in the surrounding rock. Based on ore textures and mineral assemblages as well as characteristics of surrounding rock alteration, two periods of ore deposition were distinguished： magmatic period and hydrothermal ore-forming period, which could be further subdivided into three metallogenic stages： diopside-garnet-magnetite stage, diopside-garnet-tremolite-chlorite-magnetite stage and pyrite（chalcopyrite）-specularite-carbonate stage. According to the field geological investigation, ore deposit geological characteristics and geochemistry, the genesis of Luowen iron deposit belongs to volcanic-subvolcanic iron deposit, relating to volcanic-subvolcanic rock and their hydrothermal activities. The mineralization is mainly controlled by the volcanic institutions especially crater and volcanic neck.