标题：Evolution of pegmatite ore-forming fluid: The Lijiagou spodumene pegmatites in the Songpan-Garze Fold Belt, southwestern Sichuan province, China

入藏号：WOS:000706418400001

中国科学院文献情报中心期刊分区：地学2区/TOP（2021年升级版）

本校作者： 费光春，陈昌盛，杨玉龙，登运，李佑国

来源出版物：ORE GEOLOGY REVIEWS  卷: 139  文献号: 104441

出版年：2021

第一地址： 成都理工大学

关键词： Hydrothermal diamond anvil cell；Crystal-rich inclusions；Immiscibilty；Spodumene；Pegmatite；Lijiagou

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摘要：The late to post-tectonic Lijiagou spodumene pegmatites are located in the Ke’eryin orefield, which lies in theTriassic central Songpan-Garze Fold Belt (SGFB) in southwestern Sichuan Province, China. Fluid inclusionpetrography, microthermometry and Raman spectroscopic analyses were carried out on quartz and spodumenein granites and four types of pegmatite in the Ke’eryin orefield. A Hydrothermal Diamond Anvil Cell (HDAC) wasused to observe the microthermometric behavior of crystal-rich inclusions. Five types of fluid inclusions wereidentified. Crystal-rich inclusions (Type 1) in spodumene pegmatites were trapped at high temperature (658 to741 ◦C) and high pressure (>4.7 kbar). Other inclusion types were found in granite and all types of pegmatite.Triphase CO2-H2O (CO2 + V + L, Type 2) inclusions show medium homogenization temperatures (324 to339 ◦C), medium trapping pressures (2.09 to 2.54 kbar) and low to moderate salinities (3.1 to 11.3 wt% NaClequiv). Biphase aqueous inclusions (L + V, Type 3) show similar homogenization temperatures (319 to 347 ◦C),and low to moderate salinities (5.5 to 18.0 wt% NaCl equiv). Monophase liquid CO2 (Type 4) inclusions havevery low homogenization temperatures (15.4 to 19.1 ◦C). Monophase liquid H2O (Type 5) inclusions havemoderate ice melting temperatures (–18.6 to –9.8 ◦C), and moderate salinities (18.4 to 18.5 wt% NaCl equiv).The various types of fluid inclusion reveal the P–T conditions of pegmatite formation, which records the transitionfrom a magmatic to a hydrothermal environment and indicate that the ore-forming fluid resulted from theunmixing of magmatic melt. Fluid immiscibility is the key mechanism responsible for formation of the Lijiagouspodumene pegmatites and lithium mineral precipitation occurred from a high to medium temperature CO2-richfluid. The absence of temperature and salinity gradients between granite and progressively more distal andevolved pegmatite compositions is inconsistent with formation of pegmatite magmas by fractional crystallizationof granitic magmas, but consistent with separate anatectic origins of each type of pegmatite magma.

文章链接地址: https://www.sciencedirect.com/science/article/pii/S0169136821004674