西藏喜马拉雅带稀有金属矿勘查与研究进展

Exploration and research progresses of rare metals in Himalayan belt, Tibet

关键词:  稀有金属  喜马拉雅成矿带  勘查进展  找矿方向

Key words:  rare metal  Himalayan metallogenic belt  exploration progress  prospecting direction

摘要:

长期以来，西藏喜马拉雅带以发育较多金、金锑及铅锌多金属矿为显著特色，而稀有金属矿未曾列入主流找矿方向。近年来，该带由于铍、锂等稀有金属矿的重要找矿新发现而备受广大学者关注，其相应的成矿作用研究亦有较大进展。本文在喜马拉雅带已有地质找矿成果及科学研究资料的基础上，对该带新发现的稀有金属矿勘查与研究进展进行了总结。本文提出：喜马拉雅带主要发育有伟晶岩型锂-铍矿、锡石-硫化物型锡-铍矿、矽卡岩型铍-锡-钨矿、矽卡岩型铍-铌-钽矿、钠长石花岗岩型铍-铌-钽矿、热液脉型萤石-铍矿6种稀有金属矿化类型，其中伟晶岩型锂-铍矿及锡石-硫化物型锡-铍矿最具经济意义上的找矿价值。这些稀有金属成矿作用均与中新世淡色花岗岩浆活动密切相关，属于岩浆高度结晶分异的产物，是印度-亚洲大陆碰撞造山成矿作用中的新成员，并构成了喜马拉雅带与淡色花岗岩相关的稀有金属矿成矿系列。为指导找矿勘查，今后喜马拉雅稀有金属成矿作用研究应加强如下几方面：(1)高分异淡色花岗岩-伟晶岩岩相分带与相应的稀有金属分带；(2)锂-铍-铌-钽-钨-锡共生分离机制；(3)喜马拉雅式稀有金属矿成矿模式与勘查模型；(4)稀有金属与铅锌-金锑成矿作用的关系。喜马拉雅带新发现的稀有金属成矿作用大部分靠近我国边境地区，通过进一步的勘查评价工作有望形成西藏地区具有战略意义的稀有金属成矿带。

Abstract:

For a long time, it is believed that the Himalayan belt of Tibet is characterized by abundant polymetallic Au, Au-Sb and Pb-Zn deposits, while rare metalsare not included in the main prospecting targets. The Himalayanbelt has attracted extensive attentions due to new discoveries of rare metals such as beryllium and lithium in recent years.Based on the geological prospecting achievements and scientific research progresses, this paper summarizes the exploration and research progresses of newly discovered rare metal deposits in the Himalayan belt. It is proposed that six types of rare metal mineralization occurred in the Himalayan belt, including pegmatite type lithium-beryllium deposit, cassiterite-sulfide type tin-beryllium deposit, skarn type beryllium-tin-tungsten deposit, skarn type beryllium-niobium-tantalite deposit, albialite granite type beryllium-niobium-tantalite deposit, and hydrothermal vein type fluorite-beryllium deposit. Among them, the pegmatite type lithium-beryllium ore and cassiterite-sulfide type tin-beryllium deposits have the most economic prospecting values. These rare metal deposits are closely related to the Miocene leucogranites, and are the products of the high degree of crystallization differentiation of magmatism. They are new members of the Indo-Asian continental collisional orogenic mineralization, and constitute the rare metal metallogenic series related to the leucogranites in the Himalayan belt. It is suggested that the future geological research works in the region should be focused on: (1)Zonings of the highly differentiated leucogranites lithofacies and their corresponding rare metals; (2) The symbiotic and separate mechanisms of lithium, beryllium, niobium, tantalum, tungsten, and tin; (3) Metallogenic model and exploration model for Himalayan type rare metal deposits; (4) Relationship between rare metals and Pb-Zn-Au-Sb mineralization. Most of the newly discovered rare metal deposits in the Himalayan belt are close to the border areas of China. Through further exploration and evaluation, it is expected to be a new strategic rare metal metallogenic belt in Tibet.