东昆仑成矿带拉浪麦钨多金属矿床地质特征及成矿地质条件分析

拉浪麦为青海东昆仑成矿带中东段近几年新发现的一处矽卡岩型钨多金属矿床。通过开展1∶1万地质填图,确定矿区出露地层主要为白沙河组片麻岩段(Pt1ba)片麻岩、片岩段(Pt1bb)片岩、大理岩段(Pt1bc)碳酸盐岩。断裂构造主要发育一条北东-南西向断裂F1。岩浆活动强烈,岩浆岩以英云闪长岩、花岗闪长岩类、二长花岗岩类为主,具有多期活动的特点,岩浆岩时代以加里东期、华力西期分布最广泛,其次是晚三叠世印支期。目前,通过探槽和钻探工程揭露发现5条矽卡岩型钨矿体,钨多金属矿体赋存于白沙河组大理岩段(Pt1bc)与加里东期英云闪长岩接触带的含钨矽卡岩中。矿石类型为含钨矽卡岩。通过显微镜下鉴定,金属矿物主要为白钨矿、黄铁矿,偶见黄铜矿;非金属矿物主要为石榴子石、透辉石、绿帘石、绿泥石、方解石、石英、角闪石等。围岩蚀变主要为矽卡岩化、绿帘石化、绿泥石化、蛇纹石化、硅化、碳酸盐化、黄铁矿化、黄铜矿化,矿床类型初步判断为矽卡岩型矿床,矿床形成严格受岩性条件(地层条件)、岩浆岩条件、构造条件等控制,成矿地质条件优越,深部和外围地段找矿潜力巨大,有望达到中-大型矿床规模。

Geological Characteristics and Geological Conditions of the Lalangmai Tungsten Polymetallic Deposit in the East Kunlun Metallogenic Belt

Lalangmai deposit is a newly discovered skarn-type tungsten polymetallic deposit in recent years, which locates in the Middle East segment of the Eastern Kunlun metallogenic belt in Qinghai province. The exposed stratas in the Lalangmai mainly include Baishahe Formation gneiss section (Pt1ba), schist section (Pt1bb), and marble section (Pt1bc). A northeast-southwest trending fault F1 crosses the northwestern part of the area. There is an intense and multi-phase magmatic activity, and the exposed magmatic rocks mainly are Caledonian tonalites, Variscan granodiorites, and Indosinian monzonitic granites. The ore body developed in the contact zone of tungsten-bearing skarn formation between the Baishahe Formation marble section (Pt1bc) and the Caledonian tonalites. The type of ore is skarn tungsten mineralization. The metallic minerals mainly include scheelite, pyrite, and minor chalcopyrite; the non-metallic minerals are garnet, diopside, epidote, chlorite, calcite, quartz, and hornblende, etc. The wall rock alteration includes skarnization, epidotization, chloriteization, serpentinization, silicification, carbonation, pyrite mineralization, and chalcopyrite mineralization. Evidence shows that the deep section and peripheral areas of the Lalangmai deposit have great prospecting potentials, and Lalangmai might be a medium-large tungsten polymetallic deposit.