HUANG Cong-jun¹, WANG Jiang-zhen^1,2, LI Ze-qin^1,2

(1. Chengdu University of Technology, Chengdu 610059, China;
2. State Key laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu 610059, China)

Abstract: Rare earth element (REE) geochemistry and its geological implications of fluorite from the Lala IOCG deposit were studied. Following results were obtained: (1). Lala IOCG deposit has two stages of deposition of fluorite: a metamorphic stage (MS) and a hydrothermal stage (HS); The MS fluorite can be divided into an early stage and late stage. They are closely related to the copper and molybdenum mineralization precipitated in a high temperature metamorphic fluid. They are homologous products at different stages. The HS fluorite has a different source and is a product of later geological events. (2).The total content of REE (ΣREE) in fluorite at all stages is very high, especially in the MS fluorite. From the early stage to late stage, the ΣREE of fluorite decreases gradually. The MS fluorite is one of the main carriers of REE from Lala IOCG deposit. Metamorphic metallogenic fluid has a higher ΣREE than the hydrothermal metallogenic fluid. REE distribution patterns show that light REE (LREE) enrichment and heavy REE depletion, show a right dip type distribution pattern, characterized by strong differentiation between LREE and HREE. REE distribution patterns in the fluorite are dominated by the stability of the complexes in the hydrothermal solution. (3). MS fluorite inherited the Ce and Eu anomaly characteristic of the sodic volcanic rocks. The metallogenic fluid of MS fluorite is characterized by high temperature fluid, with a negative Ce anomaly, and containing both Eu2+ and Eu3+ .The metallogenic fluid of HS fluorite is characterized by low temperature and high oxygen fugacity. (4). The content of Y may be one of the reasons for the pleochroism in fluorite from the Lala IOCG deposit, and correlates negatively to the depth of color.