M Bahrampour; M Lotfi; A Akbarpour; E Bahrampour
Abstract
The Chahmora copper deposit is located at South west of Shahrud, within the Torud-Chahshirin magmatic arc. Mineralization in the Chahmora area occurred within volcanic units of Eocene. Based on field and laboratory investigations, the outcropped rocks in the Chahmora deposit are andesite, ...
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The Chahmora copper deposit is located at South west of Shahrud, within the Torud-Chahshirin magmatic arc. Mineralization in the Chahmora area occurred within volcanic units of Eocene. Based on field and laboratory investigations, the outcropped rocks in the Chahmora deposit are andesite, andesite – basalt, trachy andesite, trachy andesite basalt and several small exposures of pyroclastic rocks such as agglomerate. Basic to intermediate sub-volcanic bodies intruded Eocene volcanic-pyroclastic sequences. The rocks are high-K, calc-alkaline to shoshonitic in nature, and are formed at a magmatic arc setting in a subduction zone. The host rocks have been affected by silicification, carbonatization, sericitization and chloritization. The textures and structures of mineralization are vein-veinlet, replacement and open space filling. According to the mineralography studies, main minerals of copper are chalcocite, chalcopyrite, covellite, digenite, cuprite, malachite and rare native copper together with hematite. Chalcocite and malachite are the most abundant minerals. Geochemical studies indicate that copper has only relative correlation with silver (R=0.894) and arsenic (R=0.520).Since silver has not founded as an independent crystalline phase, therefore copper was replaced by silver in chalcocite. . Fluid inclusion studies on trapped fluids in quartz and calcite show average homogenization temperature of 200-220ºC and fluids salinity degree of 0/97-1/37 and 3/67-4/07 %wt NaCl. Copper mineralization in the Chahmora deposit has similarities in mineralogy, host rock, texture, structure and geometry with manto-type and volcanic red bed copper deposits.
M Barati; A Akbarpour; E Fazel Tale; B Talai; M Moslehi
Abstract
The Qahr-abad fluorite deposit is located ~58 km southeast of Saqqez city, Kurdistan province. This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks. Violet, green and colorless fluorites are recognized. Quartz, dolomite, calcite and barite are ...
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The Qahr-abad fluorite deposit is located ~58 km southeast of Saqqez city, Kurdistan province. This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks. Violet, green and colorless fluorites are recognized. Quartz, dolomite, calcite and barite are gangues. REE geochemistry of the area suggests that the REE content of the fluorites lies between 20.18 and 48.38 ppm. The relatively higher concentration of LREEs in violet and colorless fluorites suggests that they formed in the first stages of mineralization. The calculation of Eu anomalies suggest that the fluorites formed in alkaline to neutral and to some extent oxidizing conditions because the Eu anomaly cover a narrow range around 1. The calculation of Ce anomaly which is negative, also confirms the oxidizing conditions for mineralizing fluids. Finally, by the studies of REE geochemistry it can be concluded that Qahr-Abad fluorite deposit is a product of hydrothermal activity of epithermal type and the mineralizing fluids are of magmatic or basinal origin by which the presence of magmatic activity in this district, it can be explained.
