Geochemistry and Microthermometry of Fluid Inclusions of Cu and Fe Mineralization in North Khour Volcanic Rocks, Northwestern Birjand

Abstract

The volcanic complex of North Khour is located in southern khorasan province, in 90 km of northwest of Birjand.The study volcanic igneous rocks are including Basaltic andesite, Andesite and trachyandesite, Latite, Dacite to Rhyodacite and pyroclastic rocks are including Tuff and breccia. The majority texture of these rocks is porphyry. Magmatic series of most samples are calc alkaline but some samples have inclination to tholleiitic serie. Furthermore in diagram of magmatic arc definition, the study rocks are situating in field of continental arc and seems which magmatism of area has been result of subduction of a oceanic crust under the continental crust. Because of the area is an upper part of a cu porphyry system, this paper is a very important research to know more about this system. Iron mineralization in area is as magnetite, hematite and as lower amount of goethite and with attention to the field observations, it seems this mineralization has magmatic origin. Burnite as alone Cu ore has been formed as primary and very little. The presence of bornite and pyrite as sulfide phases as very little and absence of other Cu primary sulfide ores in area together with secondary Cu mineralization phases in very high amounts, is showing a hydrothermal solution with high oxidation degree which has passed the latest magmatic differentiation and has caused to form surface Cu ores as calcosite in supergene zone. The thermobarrometry studies of fluid inclusions has specified degree of 10 weight percent of NaCl, 50 megapascal pressure and temperature range of 200-220 centigrade degrees for this mineralization.Therefore it seems that mineralization is related to upper parts of a Cu–porphyry system which is showing a lower temperature.