Jiajika lithium deposit in Sichuan Province,located in the southeast of Songpan-Ganzi orogenic belt,is the largest and most productive solid lithium deposit in China.Two-mica granites,microcline type(Ⅰ),microcline-albite type(Ⅱ),albite type(Ⅲ),albite-spodumene type(Ⅳ)and lepidolite-muscovite type(Ⅴ)pegmatites are developed from the inside to the outside of the Jiajika deposit.A large number of exfoliations are developed in the two-mica granites.For the element geochemical composition,the contents of rare and trace elements in granites and pegmatites show a significant abrupt relationship.There are gas-liquid two-phase inclusions,CO2-bearing inclusions,CO2-pure inclusions,crystal-rich inclusions and melt inclusions in the quartz and spodumene of various types of pegmatites.Microthermometric results show that the trap temperature of the melt inclusions is 750～800℃,and the diagenetic pressure of the pegmatite is 550～700MPa.Before complete homogenization of melt inclusions in granite,water-rich melt and water-poor melt coexist in the same system.The silicate daughter mineral-bearing inclusions in quartz and spodumene are obviously different from the melt-fluid transitional inclusions.The C-H-O isotopic results of the inclusions from the spodumene and quartz indicate that the ore-forming fluid is predominantly magmatic water and was formed in a relatively closed tectonic environment.The Ba-Sr-Nd-Hf isotopic compositions suggest that the Triassic Xikang Group metamorphic sedimentary rocks could be one of the important sources of the granites.The Zn and Li isotopes indicate that melt-melt significant immiscibility could have occurred during the magma emplacement.In summary,the Jiajika deposit may have undergone significant liquid immiscibility of granitic magma.
关键词
甲基卡/伟晶岩型锂矿床/岩浆液态不混溶作用/稀有金属/成矿模型
Key words
Jiajika/Pegmatite-type lithium deposit/Liquid immiscibility of magma/Rare metals/Metallogenic model
维普
万方数据