Application of lanthanides tetrad effect as a geochemical indicator to identify fluorite generations: A case study from the Laal-Kan fluorite deposit, NW Iran

Abstract

The Laal-Kan fluorite deposit situated in north margin of the Sanandaj-Sirjan metamorphic belt and Urmia-Dokhtar magmatic arc, NW Iran. The fluorite mineralization in the form of open-space filling, veins and veinlets have been deposited in the contact zone between highly metamorphosed schist, gneiss, amphibolite of the Paleozoic age and the Jangutaran limestone of the Precambrian age. The occurrence of convex tetrad effect and the calculated tetrad values indicate that early and late stage fluorite mineralization display various geochemical behavior, which are supported by the bivariate diagrams including T1, T3 and T4 versus each other and some geochemical parameters such as La/Ho, Y/Ho and Zr/Hf ratios. It can, therefore, deduced that fluorite have been probably formed during two stages from hydrothermal fluids with a relatively constant composition. The fluid-rock interaction during deposition of fluorite and REE-F complex were likely the main mechanisms for the occurrence of tetrad effect.

Keywords

• Lanthanides
• Tetrad effect
• Fluorite
• Laal-Kan
• Iran