F Padyar; M Rahgoshay; S Alirezaei; M Pourmoafi; A Tarantola; O Vanderhaeghe; M Caumon
Abstract
The Latala base and precious metals deposit is hosted by quartz veins, associated with a porphyry pluton intruded into a Cenozoic volcanic sequence. Euhedral quartz with sulfide mineralization such as pyrite, chalcopyrite, galena and sphalerite, with minor sulfosalts occurs in these veins as open space ...
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The Latala base and precious metals deposit is hosted by quartz veins, associated with a porphyry pluton intruded into a Cenozoic volcanic sequence. Euhedral quartz with sulfide mineralization such as pyrite, chalcopyrite, galena and sphalerite, with minor sulfosalts occurs in these veins as open space fillings and minor replacement bodies. Progressive growth of quartz crystals is evidenced by their texture revealed by cathodoluminescence imaging. The analysis of fluid inclusions indicate a decreasing homogenization temperature from 350°C in the core to 135°C along the edge of the quartz crystals with overgrowths. The presence of CO2 vapor suggested by the thermometric analysis is confirmed by Raman spectrometry. The solid phases in fluid inclusions identified as phyllosilicates, presumably muscovite and illite, chlorite, quartz and carbonate-mineral such as (Natrocarbonate, Dawsonite) by petrography and Raman spectrometry. Solid phase of halite were identified in two fluid inclusions. The homogenization temperature and salinity varies between 131 to 380 °C and 0.17 to 7.7 wt.% NaCl eq respectively. The properties of fluid inclusions corresponds to a magmatic hydrothermal fluid circulating from depth to shallower environments. The sulfur isotopic composition for galena, sphalerite, chalcopyrite and pyrite varies between -9.8 and -1‰, which correspond to values of magmatic sulfur. The δ34S values from +1.8 to -9.2‰ are in the range of hydrothermal fluids. Fluid inclusions features show a magmatic hydrothermal source which transported magmatic fluid and vapor from the depth through fractures to shallow environment. It suggests that magmatic water mixing with meteoric water was responsible for transportation of metals in Latala. Epithermal mineral precipitation during boiling, mixing and water-rock interaction formed hydrothermal quartz and sulfide mineralization. The available evidence suggests that the hydrothermal fluids changed from magmatic to epithermal in the region.
Kh. Allahyari; M. Pourmoafi; M. Khaleatbari-Jafari
Abstract
The extrusive sequence of Kermanshah ophiolite complex are exposed in Tamark and Gashor area, in east of Kermanshah and Harsin, in west of Iran. These lavas are located along the Main Zagros Reverse Fault, which marks the ophiolitic suture zone between the Zagros belt and the Sanandaj-Sirjan zone. These ...
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The extrusive sequence of Kermanshah ophiolite complex are exposed in Tamark and Gashor area, in east of Kermanshah and Harsin, in west of Iran. These lavas are located along the Main Zagros Reverse Fault, which marks the ophiolitic suture zone between the Zagros belt and the Sanandaj-Sirjan zone. These rocks with pillow structures are nominated in Tamark area as basalt to basaltic andesite and in Gashor area as basalt to basaltic trachy-andesite. According to classifications for magmatic series Tamark’s pillows are belong to subalkali series and Gashor’s pillows are belong to alkaline series. In classifications of tectono magmatic patterns, Tamark and Gashor’s basalts respectively are plotted in E-MORB and WPB. These rocks in both of pillows enriched from LILE, LREE and some HFSE and the enriched mantel is the source of the primitive magma. They represent the Neo-Tethyan oceanic lithosphere originally existing between the Arabian and Eurasian continental margins.
S. M. Hashemi; M. Emami; M. Vossoughi Abedini; M. Pourmoafi; M. Ghorbani
Abstract
In southeastern Tabas there is a 400 square kilometer area of Quaternary basalts, which is geologically located in Lut zone. According to petrographic studies and EMPA analysis, the textures of these rocks are generally porphyric and some times aphyric. The phenocrysts of these basalts are generally ...
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In southeastern Tabas there is a 400 square kilometer area of Quaternary basalts, which is geologically located in Lut zone. According to petrographic studies and EMPA analysis, the textures of these rocks are generally porphyric and some times aphyric. The phenocrysts of these basalts are generally chrisolite, augite, and plagioclase (andesine to labradorite), which are embedded in a texture of plagioclase microlites and small blades of pyroxene. According to the diagrams of accumulative amount of alkaline against the amount of SiO2, the nature of the magma is alkaline to sub-alkaline. The reason for the sub-alkaline character of some of these rocks is that the alkaline magma has been contaminated with crust materials. One of the most important reasons for this is the reduction of niobium in rocks enriched with SiO2. The alkaline samples have normative nepheline and the sub-alkaline samples normative quartz. The studies of Nd and Sr isotopes have confirmed the crust contamination and also the source for early magma of basalts is the upper parts of mantle. Based on the field studies and tectono- magmatic diagrams, these basalts are of intercontinental type because of the activities of great fault of Nayband in Quaternary and separation in their cross point reaching the earth's surface.
S. S. Mohammadi; M. Vossoughi Abedini; M. Pourmoafi; M. H. Emami; M. M. Khatib
Abstract
Bibi Maryam Granitoid body with 5 km2 exposure area is located in the east Iranian ophiolite mélange belt in Sistan suture zone. This intrusive body consists of tonalite- quartzdiorite and granodiorite. The main mafic minerals are hornblende and biotite in quartzdiorite-tonalite. Existence of ...
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Bibi Maryam Granitoid body with 5 km2 exposure area is located in the east Iranian ophiolite mélange belt in Sistan suture zone. This intrusive body consists of tonalite- quartzdiorite and granodiorite. The main mafic minerals are hornblende and biotite in quartzdiorite-tonalite. Existence of microdioritic enclave in tonalite and its absence in granodiorites is one of the main characteristics of the body. Perthitic and granophyric textures in granodiorites represent low water vapor pressure and relatively fast crystallization, respectively. Geochemical study of rock samples shows that the body is calc-alkaline and metaluminous to peraluminous. Trace element patterns in spider diagrams represent a trough for Nb and enrichment for K, Rb, Ba and Th that indicate contamination by crustal materials. Although Bibi Maryam intrusive body cuts the ultramafic rocks, it lacks petrographic and geochemical characteristics of oceanic plagiogranites. The geochemistry of the body is comparable with I-type granitoids and based on tectonic setting it can be classified as orogenic and VAG type.
