Z Bikdeli; M Ebrahimi; Gh Nabatian; M.A.A Nabatian
Abstract
Chehrabad Cu deposit is located in the Zanjan province and in the northwest corner of Central Iran. Rock units exposed in this area belong to the Cenozoic era (especially Miocene period) and include the Lower Red Formation, Qom Formation, Upper Red Formation and Quaternary deposits. In the study area, ...
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Chehrabad Cu deposit is located in the Zanjan province and in the northwest corner of Central Iran. Rock units exposed in this area belong to the Cenozoic era (especially Miocene period) and include the Lower Red Formation, Qom Formation, Upper Red Formation and Quaternary deposits. In the study area, the Upper Red Formation which hosts the mineralization consists of alternating beds of marl, siltstone, oxidized red sandstone and light gray sandstone. Mineralization has occurred within the gray sandstones of bleached zone containing organic materials. In Chehrabad, copper deposit mineralization has been recognized in five horizons. Each horizon is composed of three zones including reduced zone with mineralization, bleached zone and oxidized red zone. The dominant texture in the Chehrabad Cu deposit is replacement texture which is accompanied with other textures such as disseminated, solution seams, lens like and interparticle cement texture. Lithology (sandstone host rock), sulfide mineralogy (e.g. pyrite, chalcocite, bornite and chalcopyrite), structure and texture, stratigraphy as well as factors controlling the mineralization (presence of plant remains performing as environment reductant and also the permeability in the host rock) suggest that this deposit is similar to the red-bed type sedimentary Cu deposits which is formed during the early to late diagenesis.
Chehrabad Cu deposit is located in the Zanjan province and in the northwest corner of Central Iran. Rock units exposed in this area belong to the Cenozoic era (especially Miocene period) and include the Lower Red Formation, Qom Formation, Upper Red Formation and Quaternary deposits. In the study area, the Upper Red Formation which hosts the mineralization consists of alternating beds of marl, siltstone, oxidized red sandstone and light gray sandstone. Mineralization has occurred within the gray sandstones of bleached zone containing organic materials. In Chehrabad, copper deposit mineralization has been recognized in five horizons. Each horizon is composed of three zones including reduced zone with mineralization, bleached zone and oxidized red zone. The dominant texture in the Chehrabad Cu deposit is replacement texture which is accompanied with other textures such as disseminated, solution seams, lens like and interparticle cement texture. Lithology (sandstone host rock), sulfide mineralogy (e.g. pyrite, chalcocite, bornite and chalcopyrite), structure and texture, stratigraphy as well as factors controlling the mineralization (presence of plant remains performing as environment reductant and also the permeability in the host rock) suggest that this deposit is similar to the red-bed type sedimentary Cu deposits which is formed during the early to late diagenesis.
M Honarmand; N Rashidnejad Omran; M.H Emami; Gh Nabatian
Abstract
The Marfion Granitoid Complex is a part of Cenozoic plutonism, which located in the central part of the Urumieh–Dokhtar Magmatic Belt. This complex consists of four main intrusives, including the Mozvash micro-dioritic to micro-monzodioritic intrusive, which scattered as separate outcrops ...
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The Marfion Granitoid Complex is a part of Cenozoic plutonism, which located in the central part of the Urumieh–Dokhtar Magmatic Belt. This complex consists of four main intrusives, including the Mozvash micro-dioritic to micro-monzodioritic intrusive, which scattered as separate outcrops through the western part of the area, the Marfioun spherical tonalitic intrusive which is the most widespread pluton throughout the area, the Poudalg N-S elongated tonalitic intrusive, and the Ghalhar quartz-dioritic intrusive. The mafic microgranular enclaves with geochemical properties similar to their host granitoid are abundant in the Marfion and also in some parts of Poudalg and Ghalhar intrusives. According to geochemical data, the Marfion granitoid complex is metalominous, I-type and show the low to medium potassium calc-alkaline affinity. Using U-Pb zircon dating method, the obtained magma crystallization ages are about 50 Ma for the Mozvash intrusive and 18 Ma for the Marfion, Poudalg and Ghalhar intrusives. The geochemical evidences suggest that the Eocene Mozvash microdioritic magma is the result of the lower crust’s partial melting and and its mixture with the mantle’s melts in an active continental margin. The Miocene intrusives were derived from partial melting of a common lower crustal mafic source caused by the mantle melts in a post- collisional setting. The Mozvash micro-diorite intrusive shows less fractionated REE pattern than the Miocene intrusives. The geochemical evidences suggest a same petrogenetic model for tonalite and quartz-diorite magmas. The Marfion, Ghalhar and poudalg intrusives and their enclaves show relatively high Al2O3 and Na2O/K2O ratio and LREEs, which suggest partial melting of metabasaltic rocks. The geochemical investigations indicate that the quartz-diorites and tonalites are derived from the process of amphibole dehydration melting reacted in the lower crust.
