川西李家沟伟晶岩型锂矿床锂富集机制

——流体包裹体、白云母和锂辉石LA-ICP-MS成分的限定

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Abstract： The Lijiagou pegmatite-type lithium deposit，a major discovery within the Ke'eryin ore field of western Sichuan，is situatedattheheartofthe Songpan-Ganze fold beltand the northeastern margin of theQinghai-Tibet Plateau.Within theNo.Iorebodyof theLijiagou deposit，two distinct typesofpegmatite dikes have beenidentified： albite pegmatite （Type I）and albite spodumene pegmatite （Type I）. Tourmaline-bearing pegmatite dikes are rarely observed inouteropsand are typically found outside of the mainore bodies.Lithium is predominantlyconcentrated in spodumene within the Type I pegmatite dikes，indicating a complex mechanism of lithium enrichment driven by multistage magma hydrothermal processes.In this study，we employed microthermometric andLA-ICP-MSanalyses offluid inclusions in quartz and spodumene from various pegmatite dikes，complemented byLA-ICP-MS mapping of the spodumene and muscovite，to elucidate the characteristics of ore-forming fluids in the Lijiagou deposit. Microthermometric analyses revealed homogenization temperatures of fluid inclusions ranging from 197∘C to 429°C ， with salinities （wNaCl） varying between 0.1% and 19.9% . LA-ICP-MS analyses demonstrated that fluid inclusions in quartz and spodumene from Type I and Type I pegmatite dikes are enriched in multiple trace elements，whereas those inquartz from tourmaline-bearing pegmatites are relatively depleted.Notably，higher lithium concentrations were detected in fluid inclusions within quartz and spodumene from Type I pegmatite dikes， which also exhibited a positive corelation with homogenization temperature.The LA-ICP-MS mapping results revealed that spodumene is primarilyenriched inlithium，whilemuscovite isenriched inasuiteof trace elements，includingLi，Be，Mn，Rb，Cs， Nb，Ti，and Ta.These findings suggest thatthe magmatic-hydrothermal fluids associated with TypeIand Type I pegmatite dikes share similarities in terms of temperature，salinity，and trace element composition， withthe highest lithium enrichment occurring in the ore-forming fluids of Type I pegmatite dikes.This enrichment is likely driven by fluid exsolution from magmatic sources，facilitating the formation of spodumene in Type I pegmatite dikes， with hydrothermal alteration of muscovite also contributing to spodumene genesis.

Key Words： fluid inclusion；LA-ICP-MS；pegmatite； spodumene；Ke'eryin ore field

锂是稀有金属，被广泛应用于新能源、新材料、航空航天等多个领域（陈瑜等，2023），国际社会普遍将其列为“战略性矿产”或“关键金属”（许志琴等，2021）。（剩余22320字）