贵州习水地区锂资源的富集规律、成矿作用及找矿预测

Enrichment regularities, mineralization and prospecting prediction for lithium deposits in Xishui region, Guizhou

中文关键词:锂资源  富集规律  成矿作用  早二叠世  大竹园组  贵州

keywords:lithium deposits  enrichment regularities  mineralization  Early Permian  the Dazhuyuan Formation  Guizhou Province

中文摘要:中国沉积型锂资源多产于铝土矿（岩）中，主要分布在山西中西部、豫西、渝南、黔北、黔中、桂中等地区。贵州北部地区较为广泛发育下二叠统大竹园组铁、铝质沉积，不同程度的富集Li元素，显示该地区可能成为一个资源潜力较大的锂资源基地。文章在野外地质调查、浅表探矿工程和钻孔编录、系统取样的基础上，通过对大竹园组的岩石学、沉积学和地球化学数据统计及分析，研究总结了该地区下二叠统大竹园组Li的富集规律，探讨了Li的成矿作用，并提出该类型锂资源的找矿预测方法。习水地区下二叠统大竹园组中Li的富集程度与岩石类型、结构和沉积物的空间分布关系密切，Li主要富集在大竹园组中-上部的碎屑状铝土岩中，具有明显的横向迁移特征，与风化作用和淋滤作用强度密切相关，过于强烈和弱风化淋滤作用均不利于Li的富集，而中等-强烈风化淋滤作用是Li富集的关键。在贵州务川、正安、道真、桐梓、习水等地区，高度富集Li的岩石具有35%<w(Al₂O₃)<53%和0.8<w(Al₂O₃)/w(SiO₂)<3.5的特征，可通过含锂岩系厚度、碎屑状铝土岩厚度、w(Al₂O₃)和w(Al₂O₃)/w(SiO₂)等多指标值等值线的叠加，优选出有利的找矿预测区段。

Abstract:Sedimentary-type lithium deposits in China occur mainly in bauxite and widely distribute in the central and western Shanxi, western Henan, southern Chongqing, northern Guizhou, Central Guizhou, central Guangxi and other regions. The iron and aluminum-bearing sediments of the Lower Permian Dazhuyuan Formation are enriched in different degrees with Li in northern Guizhou, where may be a potential lithium resource base. Based on field geology survey, prospecting projects and systematic sampling, detailed study of petrology, sedimentology and geochemistry on the rocks from the Dazhuyuan Formation was carried out, the Li enrichment regularities in the Dazhuyuan Formation was summarized, the ore-forming mechanism was discussed, and the prospecting prediction method of Li deposits in the lower Permian Dazhuyuan Formation was proposed. The enrichment degree of Li in the Lower Permian Dazhuyuan Formation in the Xishui region is closely related to the rock type, rock texture and spatial distribution of sediments. Li is mainly concentrated in the clastic bauxitic rock of the middle and upper Dazhuyuan Formation, which is closely related to the intensity of weathering and leaching. Both excessive strong and weak weathering-leaching are not conducive to Li enrichment, and moderate-strong weathering-leaching are the key to lithium enrichment. In addition, lithium has obvious characteristic of lateral migration. When the w(Al₂O₃) content ranges from 35% to 53% and the w(Al₂O₃)/w(SiO₂) ratio ranges from 0.8 to 3.5，Li was highly enriched in the sediments of the Lower Permian Dazhuyuan Formation. Therefore, favorable prospecting prediction areas are selected by isopach superposition of multi-index values, such as thickness of the lithium-bearing rock series, thickness of the clastic bauxitic rock, w(Al₂O₃) content and w(Al₂O₃)/w(SiO₂) ratios.