湖相沉积黏土型锂矿主要地质特征及成因

Geological characteristics and genetic mechanism of the lacustrine sedimentary clay type lithium deposit

锂是重要的战略性新能源矿产,主要有卤水型、硬岩型和沉积黏土型3种类型。前两者已有大量开采。现阶段具有开发利用前景的沉积黏土型锂矿主要产于湖相盆地中,其产出规模大、层位浅、矿体分布稳定、厚度大、品位高,具有重要的地质意义和潜在的经济价值。现已发现的湖相沉积黏土型锂矿床主要分布在北美洲、欧洲和中国。该类型矿床赋矿沉积岩的沉积特征、锂的赋存状态、成矿物质来源、成矿环境与成矿机理等研究目前还较薄弱。本文主要介绍全球主要湖相沉积黏土型锂矿的地质特征、赋矿矿物特征和成矿规律,并对国内外湖相沉积黏土型锂资源的成矿作用机理进行综合分析。湖相沉积黏土型锂矿床中锂主要赋存于蒙脱石、伊利石等黏土矿物中,个别为独立含锂矿物贾达尔石。锂的主要物质来源及成矿方式有多种,包括喷发至湖盆中的富锂火山岩(特别是火山灰地层)、深部富锂岩浆热液运移至湖相盆地中并与沉积黏土水岩反应形成,或者通过富锂盐湖卤水与围岩黏土岩的相互作用使得锂吸附在黏土矿物中。全球湖相沉积锂成矿作用的差异主要是成矿物源区和沉积环境的差异所致。

Lithium is an important strategic new energy metal resource.There are mainly three types of lithium resources,including the brine type,hard rock type,and sedimentary clay type.Especially,the brine type and hard rock type Li resources have already been extensively mined.At present,the sedimentary clay type lithium deposits with high development and utilization prospects mainly occurred in lacustrine basins.They are characterized with large output scale,shallow depth occurrence,stable orebody distribution,large thickness of orebody,and high ore grade,with important geological significance and potential economic value.The discovered lacustrine sedimentary clay type lithium deposits are mainly distributed in North America,Europe,and China.However,researches on the sedimentary characteristics,of the sedimentary rocks which hosted this type of deposit,the occurrence state of lithium,the source of ore-forming materials,the ore-forming environment and ore-forming mechanism of this type of deposit are still relatively poor.In this article,we have introduced main geological features,ore-bearing mineral characteristics,and mineralization regularities of major lacustrine sedimentary clay type lithium deposits worldwide,and have comprehensively analyzed the ore-forming mechanism of this type lithium resources at home and abroad.Lithium in lacustrine sedimentary clay type lithium deposits mainly occurred in clay minerals,such as smectite and illite,and occasionally occurred in individual independent lithium-bearing minerals such as jadarite LiNaSiB3O7(OH).There are various sources and mineralization styles of lithium.The lithium could be sourced from the Li-rich volcanic rocks(especially volcanic ash)that erupted into lake basins,and the Li-rich magmatic hydrothermal fluids that migrated into lake basins.This type lithium deposits could be formed through the reaction of Lirich magmatic hydrothermal fluids and sedimentary clays,or the Li-adsorption in clay minerals by the interaction between the Lirich brine and surrounding clay rocks.The differences in the sources and sedimentary environments of ore-forming materials for this type of deposits had led to the diversity of lithium mineralization in lacustrine sediments around the world.