Fluid Characteristics and Evolution of the Zhawulong Granitic Pegmatite Lithium Deposit in the Ganzi‐Songpan Region, Southwestern China

Abstract

The Zhawulong granitic pegmatite lithium deposit is located in the Ganzi‐Songpan orogenic belt. Fluid inclusions in spodumene and coexisting quartz were studied to understand the cooling path and evolution of fluid within albite–spodumene pegmatite. There are three distinguishable types of fluid inclusions: crystal‐rich, CO2–NaCl–H2O, and NaCl–H2O. At more than 500°C and 350∼480 MPa, crystal‐rich fluid inclusions were captured during the pegmatitic magma‐hydrothermal transition stage, characterized by a dense hydrous alkali borosilicate fluid with a carbonate component. Between 412°C and 278°C, CO2–NaCl–H2O fluid inclusions developed in spodumene (I) and quartz (II) with a low salinity (3.3–11.9 wt%NaCl equivalent) and a high volatile content, which represent the boundary between the transition stage and the hydrothermal stage. The subsequentNaCl–H2O fluid inclusions from the hydrothermal stage, between 189°C and 302°C, have a low salinity (1.1–13.9 wt%NaCl equivalent). The various types of fluid inclusions reveal the P–T conditions of pegmatite formation, which marks the transition process from magmatic to hydrothermal. The ore‐forming fluids from the Zhawulong deposit have many of the same characteristics as those from the Jiajika lithium deposit. The ore‐forming fluid provided not only materials for crystallization of rare metal minerals, such as spodumene and beryl, but also the ideal conditions for the growth of ore minerals. Therefore, this area has favorable conditions for lithium enrichment and excellent prospecting potential.