Economic Geology
iman shojaian; A. Akbarpour; Khalil Baharfirouzi; Majid vanaei
Abstract
The Darreh Rahim Iron deposit occurred in 2km northwest of Ghohroud village, 25 km south of Kashan city, in Ghamsar county suburb, Isfahan province, on Urumyeh-Dokhtar magmatic belt. . Based on the petrography data, the main intrusive body of the district has medium to coarse granular texture and granodiorite ...
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The Darreh Rahim Iron deposit occurred in 2km northwest of Ghohroud village, 25 km south of Kashan city, in Ghamsar county suburb, Isfahan province, on Urumyeh-Dokhtar magmatic belt. . Based on the petrography data, the main intrusive body of the district has medium to coarse granular texture and granodiorite rock composition. Injection of this intrusive body in the Cretaceous age limestone caused the formation of skarn processes and related Iron mineralization. An assemblage of pyroxene, chlorite, garnet, calcite and quartz are the main components of skarn and also gang minerals of the ore. Also all evidences of mineralogy, structure and texture, geochemistry and tectonic setting and Ni/(Cr+Mn)toTi+V andCa+Al+Mn toTi+V diagrams showed a similarity of the DarrehRhim ore deposit to Iron-Copper mineralization.
M. R. Rezapour; V. Simmonds; M. Moazzen; R. Hajialioghli
Abstract
The Qohrud granitoid body of Miocene age is located 40 km SW Kashan, ranging in composition from granite through granodiorite to tonalite. Hydrothermal activities following the magma intrusion have brought about formation of various coarse automorphic and colored quartz crystals within the fractures ...
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The Qohrud granitoid body of Miocene age is located 40 km SW Kashan, ranging in composition from granite through granodiorite to tonalite. Hydrothermal activities following the magma intrusion have brought about formation of various coarse automorphic and colored quartz crystals within the fractures and cavities of different lithologies. The quartz crystal varieties include transparent, semi-transparent, pale green, yellow and black crystals, as well as those with smoky and reddish brown roots and also crystals containing tiny acicular rutile inclusions. Mineral chemistry, as well as fluid and solid inclusion studies on the colored and automorphic quartz crystals indicate that various physical and chemical factors, such as temperature, pressure, magma and host rock compositions, hydrothermal fluids and the associated alterations, as well as pH and Eh were involved in the formation of these automorphic colored crystals. The solid inclusions within these automorphic quartz crystals might have formed in two ways: 1) introduction of the necessary elements for the formation of quartz and the solid inclusions by the fluids and then, entrapment of these inclusions within the growth layers of quartz crystals; 2) direct introduction of very fine mineral particles within the growth layers of quartz, leading to occurrence of various colored crystals. Smoky crystals can be formed by the replacement of Si by Al and also by the presence of U and Th within them. The reddish color of quartz crystals was recognized as the result of the presence of fine rutile needles. Automorphic black-colored quartz crystals are formed at oxidant and almost high pH conditions by initial precipitation of magnetite and then, manganese oxides at the outermost growth layers. The green quartz crystals have been resulted from chloritic and epidotic alterations within the host and neighboring rocks.
S. M. Tabatabaeimanesh; H. Safaei; A. S. Mirlohi
Abstract
In south of Kashan, early Paleozoic volcanic rocks are a part of Ghohrudmountains. In Iran structural- sedimentary division, these volcanic rocks located inUrumieh- Dokhtar zone. These volcanic rocks are basic to semibasic and mostly involved basalt. Geochemical investigations of these rocks show the ...
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In south of Kashan, early Paleozoic volcanic rocks are a part of Ghohrudmountains. In Iran structural- sedimentary division, these volcanic rocks located inUrumieh- Dokhtar zone. These volcanic rocks are basic to semibasic and mostly involved basalt. Geochemical investigations of these rocks show the alkaline nature and the intra-continental rift geotectonic setting in their formation time. The Isfahan fault is a north-trending fault across the Sanandaj-Sirjan zone. This fault is one of the old and basement fault that was active in the early Paleozoic. The unique present of Silurian volcanic rocks in this area can refer to the activation of the north part of this fault that was created by extension phases after Caledonian orogeny.
