Z. Mohammadzadeh; M. Ghaderi; S. Alirezaei; J. Hassanzadeh
Abstract
The Raziabad porphyry copper deposit is located 30 km north of the city of Jiroft, in southeastern part of the Urumieh-Dokhtar magmatic arc, southeastern Iran. Several intrusive bodies including diorite, gabbro, granodiorite and quartz-diorite associated with groups of dikes with similar composition ...
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The Raziabad porphyry copper deposit is located 30 km north of the city of Jiroft, in southeastern part of the Urumieh-Dokhtar magmatic arc, southeastern Iran. Several intrusive bodies including diorite, gabbro, granodiorite and quartz-diorite associated with groups of dikes with similar composition as well as dissimilar composition with the intrusions, intruded into the Raziabad porphyry system. The porphyry copper mineralization is associated with the granodiorite which intruded into dioritic, gabbroic and volcano-pyroclastic rocks. The magmatic activities continued after mineralization and lead to the emplacement of the quartz-diorite as well as intrusion of two groups of micro-granitic and andesi-basaltic dikes cutting the ore body, causing geometric complexity of the ore body. The alteration zones include potassic and magnetite-rich silicification zones, relatively restricted calcic zone, and propylitic zone. Phyllic alteration with restricted expansion and weak intensity overprinted on potassic alteration. The hypogene mineralization has occurred as disseminated, stockwork and veinlet styles closely associated with the potassic alteration zone. The main ore minerals are chalcopyrite+ magnetite+ pyrite with minor molybdenite, pyrrhotite, galena and sphalerite. The oxidation and enriched supergene zones are variable and restricted to the shallow levels. Hydrothermal activity in Raziabad deposit is classified into four stages on the basis of hydrothermal mineral assemblage and veinlet relation. The stages include: 1) calcium silicate-magnetite-quartz stage; 2) potassium silicate-sulfide-quartz-magnetite; 3) sericite-quartz-pyrite stage; 4) chlorite-epidote-calcite-pyrite±actinolite.
R. Jamali Ashtiani; J. Hassanzadeh; M. Rahgoshay
Abstract
Two different ages of Precambrian and Jurassic are considered for the Zayanderud metamorphic complex in the Najafabad and Chadegan geology maps, respectively. This disagreement has made these two maps to be the most incompatible adjacent maps. The metamorphic complex is nonconformably covered by fossiliferous ...
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Two different ages of Precambrian and Jurassic are considered for the Zayanderud metamorphic complex in the Najafabad and Chadegan geology maps, respectively. This disagreement has made these two maps to be the most incompatible adjacent maps. The metamorphic complex is nonconformably covered by fossiliferous Permian limestones suggesting a Pre-Permian age. This relative age is supported by 206Pb/238U zircon ages of Neoproterozoic for the cross-cutting mylonitic orthogneisses. In this paper we discuss the Jurassic age considered for protolith of the metamorphic and granitoid rocks in the Chadegan map as an misunderstanding in field observations. Also we argue that Ar/Ar Jurassic ages represent the time of metamorphism and do not reflect the protolith age.
