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.A Samaie; F Malekghasemi; V Simmonds
Abstract
The area is located in 25 Km southwest of kazerun city in the Zagros folded zone. The Phosphate beds have been deposited in the core of the Sarbalesh-Baznak anticline with NW-SE trend. Stratigraphically, the Gurpi, Pabdeh, Asmari, Gachsaran, and Bakhtiyari Formations are outcropped in this area. Petrographic ...
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The area is located in 25 Km southwest of kazerun city in the Zagros folded zone. The Phosphate beds have been deposited in the core of the Sarbalesh-Baznak anticline with NW-SE trend. Stratigraphically, the Gurpi, Pabdeh, Asmari, Gachsaran, and Bakhtiyari Formations are outcropped in this area. Petrographic studies show that phosphate-bearing layers are composed of calcite, phosphate, glauconite and iron oxide with packstone to wackestone texture. Microfossil studies proved the age of Oligocene for the phosphate layers. The XRF and XRD analyses demonstrated that the phosphate-bearing mineral is fluor-apatite (Ca (PO4)3F). Sedimentary phosphate in this area was formed under the high energetic environment condition, phosphate saturated waters, and in the boundary of oxidation – reduction zone.
F. Malekghasemi; V. Simmonds
Abstract
The purpose of this study is to determine the genesis of the manganese occurrences around the Hashtroud city, with special regard to Idahlu- Jokandy region. In this region Mn mineralization is sparse and rather extensive. Mineralization has originated from hot springs and precipitated on the earth surface. ...
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The purpose of this study is to determine the genesis of the manganese occurrences around the Hashtroud city, with special regard to Idahlu- Jokandy region. In this region Mn mineralization is sparse and rather extensive. Mineralization has originated from hot springs and precipitated on the earth surface. The mineralization is mainly massive and vein form. Due to the presence of hot springs and their traces in the study area, it can be concluded that Fe and Mn components were in the hot springs as solution and precipitated on the earth surface or penetrated into existing fractures and faults of the region by the hot springs and consequently caused the mineralization. The main Mn minerals are pyrolusite and psylomelane accompanied by gypsum, travertine, barite and jasper
