Houshang Pourkaseb; Alireza Zarasvandi; Mansour Adelpour
The Heydarabad ophiolitic mélange is hosted in the Sistan suture zone, which marks the boundary between the Lut and the Afghan continental blocks and comprises of mantle peridotites ...
The Heydarabad ophiolitic mélange is hosted in the Sistan suture zone, which marks the boundary between the Lut and the Afghan continental blocks and comprises of mantle peridotites and crustal sequence. The studied mantle peridotites are dominated by harzburgite and clinopyroxene-rich harzburgite that formed in mid-ocean ridge (MOR) setting. These mantle peridotites, due to the effect of hydrothermal solutions, have been altered. Moreover, iron-copper mineralization developed by the influence of hydrothermal fluids moving through the fractures and the faults. The textures and structures of mineralization formed as open space filling, disseminated, vein-veinlet and replacement. Two important stages could be recognized for the mineralization in this area. The first stage includes processes, which caused the development of sulphide mineralization in the mantle peridotites. The second stage is related to oxide fluids, which led to magnetite mineralization.Based on detailed electron microprobe study, olivine, orthopyroxene, clinopyroxene and spinel are the essential rock forming-minerals of the rocks under study. Most of the olivines from the mantle peridotites are serpentinized but some, with forsterite composition, are fresh. The composition of the ortho- and clinopyroxenes is enstatite and diopside respectively and the spinels are classified as Al-rich Cr-spinel type.