Dolomites and breccia in KamarPosht fluorite mine, Elika Formation, Central Alborz

Fluorite mineralization in Kamar Posht mine, east of Central Alborz, is mostly occurred in dolomitic limestone rocks of the Elika Formation. The aim of this current research was to recognize the types of breccia and dolomite based on microscopic studies (transmitted and cathodoluminescence light) and ore fabric and texture applying to the genesis of this deposit. Using the above methods combined with time-space relationship between dolomites and fluorite led to recognition of 2 main groups of dolomites including (1) pre-mineralization dolomicrites without luminesce in the matrix of host dolomitic limestone and (2) dolomicrosparite-dolosparites associated and coeval with mineralization that show red to orange-yellow luminescence color . Pre-mineralization dolomicrites introduced as shallow buried diagenetic-type, whereas syn-mineralization dolomicrosparite-dolosparites interpreted to form due to re-crystallization of primary dolomicrites of host rock and/or precipitation of hydrothermal solution (basinal brine) causing dolomitic alteration. Dissolution-collapse and faults breccias dominated over diagenetic breccia and were main features of mineralization in Kamarposht mine. They were interpreted as evidence of epigenetic origin of fluorite mineralization in high-grade zones of the KamarPosht mine. They were probably formed as a result of post-diagenetic processes (tectonic and basinal brines) on dolomitic limestone host rocks overlaying clastic rocks of Shemshak group.   Keywords: