On the Structural Backgrounds of the Large-scale “Hard-rock Type” Lithium Ore Belts in China
XU Zhiqin;WANG Rucheng;ZHAO Zhongbao;FU Xiaofang;School of Earth Sciences and Engineering,Nanjing University;Institute of Geology,Chinese Academy of Geological Sciences;Geological Survey of Sichuan Province;
Ore deposits are widely developed in our planet.Like all other geological units,they not only record various geological data,such as material compositions,fluid properties and composition,and thermalevolution of the Earth,but also reflect the physical-chemical conditions and structural setting of diagenesis and mineralization,as well as driving forces of the deep Earth.Lithium(including other rare earth metals)has become a new energy and new economic material in the future from ordinary mineral resources.Therefore,it has significant economic and strategic significance.The breakthrough in exploration for Libearing pegmatite deposits has made the "hard-rock type"lithium deposits the strategic resources of national future new-energy demand.Hard-rock type lithium pegmatite deposits possess unique geological physical and chemical forming conditions.A series of research results has made in the component division of pegmatite,discovery of new minerals,enrichment mechanism of rare metals during geochemistry evolution,provenance of melt-fluid,magmatic crystallization and differentiation,and physicochemical conditions of diagenesis and mineralization.However,tectonic and geodynamic backgrounds for lithiumbearing pegmatite and related mineralization are still at an exploratory stage.From perspective of the tectonic background of hard-rock type lithium mineralization belt in China,this study discusses tectonic factors and exploration outlook of lithium resources in the collisional and accretionary orogenic belts.Studies have shown that the Markam-Yajiang-Karakoram giant lithium ore belt in western China is distributed in the 2800 km-long Songpan-Ganzi-Tianshuihai terrane in the northern margin of the Qinghai-Tibetan Plateau.This was formed by the closure of the Paleo-Tethys and the convergence among the Kunlun Terrane,the Qiangtang Terrane and the Yangtze Terrane during Indochina collision orogenic event.The formation of lithium ore belts,which are represented by lithium deposits in the Markam,Jiajika,and Dahongliutang areas,was spatiotemporally related to the gneiss dome formation resulted from granitic magmatism of Indochina orogeny,emplacement of regionally melting granite pegmatite veins,and high-temperature Barrovian type metamorphism of the Triassic metaturbidites.The Altai accretionary orogenic belt of the Central Asian orogenic system,which was the result of the continental accretionary during the evolution of the ancient Asian Ocean,is characterized by the dome tectonic setting with compound effect of magmatism,anataxis,metamorphism and mineralization during the Paleozoic orogenic process,and contains Triassic REE-bearing pegmatite veins unrelated to Paleozoic granite genesis.The authors believe that the Songpan-Ganzi-Tianshuihai orogenic belt is the significantly strategic"hard-rock type"lithium ore belt in China.Therefore,identifying the formation mechanism and tectonic evolution of the Triassic gneiss dome,as well as spatiotemporal relation and control effect of magmatism-anataxis-metamorphism on mineralization during the orogenic process is very important constraint to formation mechanism of lithium ore deposits.This study investigated the relation between ore-bearing pegmatite veins and granitic magma crystallization and differentiation,migration of lithium element,and emplacement process of enriched melt,and finally determined the source of rare earth elements such as lithium,strontium,barium,and tellurium.Scientific drilling project was also implemented in lithium deposit cluster areas and scientific section of tectonic-lithology-mineralization of gneisis dome was finally established.In short,conducting geological multidisciplinary research on the structural background and continental dynamics of large-scale lithium ore belts is a scientific approach to make breakthrough in lithium ore exploration.
【Fund】： 南京大学人才基金;; 自然基金重点项目《No.40921001》;; 中国地质调查局项目《No.1212010818094》项目共同资助的成果
【CateGory Index】： P618.71
【CateGory Index】： P618.71