Rare earth elements geochemistry of fluorite from Bozijan (Chekap) deposit, Markazi Province, Iran

Author

Department of geology, Islamic Azad University-Behbahan Branch

Abstract

Fluorite vein mineralization occurs in slates and phyllites of Lower Jurassic Shemshak Formation and scarcely in Triassic limestones located in the west of Mahallat city in Markazi Province of Iran. The ore consists mainly of fluorite, quartz, calcite and iron oxides. The subordinate components are galena, pyrite, manganese oxides and malachite. Local wall rock alterations include argillization and silicification. The nature of the mineralization and ore–host rock relationships indicate an epigenetic mode of formation for the fluorite mineralization. Analysis of fluorite samples revealed an extremely low content (average: 8.28 ppm) of REE. The Tb/Ca–Tb/La ratios, as well as Y/Ho ratios and strong positive Y anomalies of shale–normalized REE patterns, invariably suggest a hydrothermal origin for Bozijan fluorites. The chondrite–normalized REE patterns display an identical trend for fluorites and host rocks, which can be interpreted as a genetic association for them and that F was probably derived from the host rocks. Ce/Yb ratios and chondrite–normalized patterns revealed that the fluorites are enriched in LREE relative to HREE. This indicates that all the fluorites were crystallized in the early stage of mineralization. Ce/Ce* ratios show persistent negative Ce anomalies, indicating high ƒO2 in the hydrothermal fluid. Eu represents both positive and negative anomalies, probably caused by fluorite crystallization below and above 200 °C. In Sr–Eu/Eu*, Ce/Ce*–Eu/Eu*, (La/Yb)n–Eu/Eu* and (Tb/Yb)n–(La/Yb)n diagrams, data points do not overlap with the fields represented by fluorite–bearing Au–Ag deposits from elsewhere, indicating a very low potential for precious metals mineralization in the studied deposit.

References

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Advanced Applied Geology
Volume 1, Issue 2 - Serial Number 2
January 2012
Pages 113-125

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