Economic Geology
Mehrdad Movahedi; Mohammad Yazdi; Mehrdad Behzadi
Abstract
The Oshvad skarn type deposit was formed during the intrusion of a felsic mass into the Permian and Triassic carbonate rocks and ion exchange occurred between the intrusion mass and these units. In order to determine the properties of the mineralizing fluid in this skarn, several fluid inclusions in ...
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The Oshvad skarn type deposit was formed during the intrusion of a felsic mass into the Permian and Triassic carbonate rocks and ion exchange occurred between the intrusion mass and these units. In order to determine the properties of the mineralizing fluid in this skarn, several fluid inclusions in quartz and calcite minerals of the mineralization zone were analyzed. The results show that these minerals have two types of fluids inclusion. The first group includes L+V type, low to medium salinity, and with homogenization temperature of 194 to 480°C. The second group includes V+L type, low to moderate salinity, and homogenization temperature of 338 to 448°C. The origin of L+V type fluid inclusions are magmatic-meteoric and metamorphic type and V+L fluid inclusions are metamorphic type. Mixing and dilution of fluids occurred during the mixing of meteoric waters with magmatic-metamorphic fluids. These processes are the main factors of mineralization in this deposit. Fluid inclusions data show that fluid pressure has been 50 to 150 bars during the ore-forming minerals. Also, the fluid temperature has been between 200 to 360°C. The data suggest that the ore minerals have been formed in depth of 650 meters lower than the old water table.
S Alipour; P Shirmohammadi; Y Rahimsouri; H Bagheri
Abstract
Baba-Nazar garnet occurrence is located in northwest part of Sanandaj-Sirjan geological zone. Rock units in the area, including hornfels, garnetite and extensively weathered host rocks in contact with granite indicate garnet may have formed by metamorphism of clay-argillite, sandstone and calcareous ...
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Baba-Nazar garnet occurrence is located in northwest part of Sanandaj-Sirjan geological zone. Rock units in the area, including hornfels, garnetite and extensively weathered host rocks in contact with granite indicate garnet may have formed by metamorphism of clay-argillite, sandstone and calcareous rocks. The mineralogical and petrographical studies revealed that the evolution of mineralization has occurred during several progressive, retrograde and supergene alteration, while garnet has formed during progressive alteration. The results of the petrographical study of fluid inclusions show that most of the fluid inclusions in the garnet crystals fall in two groups: (1) Primary inclusions distributed randomly on the crystal faces and (2) secondary inclusions oriented along fractures and cleavage surfaces. Based on the inclusion diversity, four groups of these inclusions were differentiated: (1) single-phase liquid, (2) two-phase liquid-vapor, (3) solid multi-phase and (4) two-phase liquid–liquid. Micro thermometry of fluid inclusions in the garnet and quartz crystals show homogenization temperatures and salinities from 318 to 438 °C and 18.63 to 22.71 weight percent NaCl equivalent for garnet, and from 209 to 219 °C and 239 to 254 C° with 4.18 to 10.61 weight percent NaCl equivalent for quartz crystals.