Mineralogy and geochemistry of the Dehshir listvenites, central Iran

Abstract

The Dehshir listvenites are located in the Dehshir–Baft suture zone, central Iran. This suture zone includes a sequence of Cretaceous ophiolite rocks, pieces of altered upper mantle rocks, serpentinites and Cenozoic volcanic rocks. The listvenites (both para-and ortho-listvenites) formed close to shear zones, faults and fractures and occur as continuous and discontinuous veins and masses. Based on mineralogical and geochemical studies three types of listvenites can be distinguished (1) carbonate listvenite, (2) silica listvenite and (3) silica–carbonate listvenite. The listvenites contain a wide range of silicate and carbonate minerals related to different hydrothermal fluid compositions and different rock types. The chemical composition of the listvenites was controlled by shear zones and reactions between country rocks and hydrothermal solutions under variable pT-conditions. Listvenites of the study area have high potential for sulfide mineralization compared to ordinary serpentinite. Silica listvenites are more variable in mineralogy compared to carbonate listvenites and enrichment of metals, such as Au content, increases with silica content. Fluid inclusion studies of the Dehshir listvenites indicate the former presence of a low salinity and high temperature (115 – 300 °C) hydrothermal fluid during listvenitization. © 2019 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany.