Investigation of alterations and ore potential in ultramafic rocks in the çomakli village (Van-Eastern Anatolia)

The study area includes Çomaklı village and its surrounding units in Van province. The region is generally composed of sedimentary and ophiolitic units in different lithologies and ages ranging from Jurassic to the present. The ophiolitic units observed in the region are generally seems to be as a melange. The ophiolitic units observed in the Dirbi Melange cover large areas in the region. Ultramafic rocks in the ophiolitic units are generally affected by alteration and serpentinized. In study areas with serpentinization and lisvenitization are common in fault zones. In petrographic studies, olivine, orthopyroxene, clinopyroxene and chromium spinel minerals were observed in peridotites. These rocks were named as harzburgite because of these mineral associations observed in the peridotites. With the introduction of water into the harzburgites, the rock started to serpentinizate. Due to the presence of chrysotile lizardite minerals observed in serpentinites, formation temperatures were low (<350 °C). With the continuation of hydrothermal fluid entry into the rock after serpentinization, it was determined that silicification developed first with the presence of low temperature fluid phases, first carbonation and subsequent temperature increase in the following sites. Geochemical studies showed that the lisvenitization observed in the region was first serpentinized by low temperature hydrothermal waters along fractures and faults that developed by the tectonism of ultramafic rocks and then they were altered by rich hydrothermal fluids such as Si, Ag, Ni, Co and Mo which have been enriched.