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Open Access Article
1 - Microbiostratigraphy of the lower Cretaceous strata from South East of Maragheh, NW Iran
Mahmoud Reza Majidifard Parvaneh Zavar Morteza Taherpour Khalil Abad Masoud Zamani Pedram Taiebeh Mohtat -
Open Access Article
2 - The Sungun porphyry magma resource and the 120,000-year difference in age between the main stock and the first dike: New evidence from 87Sr/86Sr, 143Nd/144Nd and Pb, SHRIMP U–Pb zircon dating in NW Iran
Shohreh HassanpourThe Sungun copper porphyry deposit is hosted by a Tertiary magmatic complex in the Azarbayjan province , northwestern Iran. The Sungan mine in its southern and eastern parts is limited by early Miocene volcanic and by Late Creta MoreThe Sungun copper porphyry deposit is hosted by a Tertiary magmatic complex in the Azarbayjan province , northwestern Iran. The Sungan mine in its southern and eastern parts is limited by early Miocene volcanic and by Late Cretaceous limestone rocks in northern and eastern parts respectively . The Sungun deposit is associated with a suite of porphyritic granitoids and late dikes intruding within Oligo-Miocene andesitic and upper Cretaceous limestone. The Sungun porphyry system developed in multi-stage, central intrusive rocks of the early Miocene age in the Tertiary Arasbaran Magmatic Zone (AMZ). A late post-mineralized dike (DK1a) is the first dike system after the replacement of the Sungun porphyry. It has been dated with a 20.57±0.27 Ma (±2 σ). New zircon SHIRIMP U-Pb data indicates that the Sungun porphyry crystallized within the time span from 20.69±0.37 Ma (±2 σ), and the Sungun porphyry and DK1a represent a near-dated intrusive with an age difference of about 0.12 Ma (120,000 y). Their range of 87Sr/86Sr ratios (0.70467 to 0.72278), 143Nd/144Nd ratios (0.51275 to 0.51214), 87Rb/86Sr (0.67497 to 0.67415 values), lead isotopes ranges from 18.67 to 18.86, 15.65 to 15.66, and 38.93 to 39.06 for the ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb respectively, suggest the high contributions of depleted mantle-derived magmas in the generation of Sungun stock, but crustal-contaminated origin for monzonitic body in late magmatic activities in the area. This study shows that the source of the Sungun stocks is categorized in the upper crust, typically similar to the source of porphyry deposits. Manuscript profile -
Open Access Article
3 - Mineral chemistry and thermobarometry of Eocene alkaline volcanic rocks in SW Germi, NW Iran
Mohammad Mobashergermi Reza Zarei Sahamieh Mehraj Aghazadeh Ahmad Ahmadikhalaj Gholamreza Ahmadzadeh -
Open Access Article
4 - Strain geometry and structural analysis of the Oshnavieh ophiolite (NW Iran): A new segment of the Neo-Tethys puzzle
Majid Niromand Mahdi Behyari Yousef Rahimsouri -
Open Access Article
5 - Study of A-type granite from the South of Lake Urmia, Sanandaj-Sirjan Zone: implications for the Neotethys opening in Iran
Nasser Ashrafi Mehrdad Pourmohsen Morovvat Faridazad -
Open Access Article
6 - Geology and geochemistry of skarn deposits in the northern part of Ahar batholith, East Azarbaijan, NW Iran
Habib Mollai Abdol Majid Yaghubpur Reza Sharifiyan AttarPrincipal Skarn deposits along the northern margin of the Ahar batholith from west to east include Mazraeh, Vine and Gowdoul skarn deposits. Among these skarn deposits, the Mazraeh Cu-Fe Skarn deposit is the most typical skarn deposit in the NW Iran. This skarn deposit MorePrincipal Skarn deposits along the northern margin of the Ahar batholith from west to east include Mazraeh, Vine and Gowdoul skarn deposits. Among these skarn deposits, the Mazraeh Cu-Fe Skarn deposit is the most typical skarn deposit in the NW Iran. This skarn deposit is located 5 km. north of Mazraeh village and 20 km north of Ahar town. The origin and development of the skarn can be related to the granitic intrusion of Oligo- Miocene age which has intruded a sequence of calcareous rocks. On the basis of petrological considerations the skarn can be subdivided into Exoskarn, Endoskarn and Ore skarn. The main mineral constituents of the skarns are garnet, magnetite, calcite, chalcopyrite, epidote, hematite and pyroxene, accompanied by quartz, pyrite, bornite, coevalite, chalcocite, plagioclase and chlorite. The bulk chemistry and spatial variation characteristics indicate that the endoskarn was the result of interaction between Mazreah granodiorite with crystalline limestone and metasomatic alteration through hydrothermal fluid enriched in Mg, Fe, Cu, P, Ag, Zn, Pb, Cd, Mo, Mn, etc. These elements point toward a magmatic source, and have been contributed to the system from the magma as well as the host rock. The crystalline limestone was the source for Ca and Mg in case of endoskarn. The transformation of granodiorite into endoskarn was accomplished by addition of 1.4 to 15% CaO along with 7.17% of total iron into the granodiorite was accompanied by depletion of about 15.5% SiO2 (average 53.5%). Manuscript profile -
Open Access Article
7 - A study of different zoning types in clinopyroxenes of sodic and potassic alkaline volcanic rocks from North Lahrud, NW Iran
Gholamreza Ahmadzadeh Reza ZamaniClinopyroxene phenocrysts and microphenocrysts in potassic and sodic Eosen alkaline volcanic rocks from the northern Lahrud (NW Iran) record various stages in the crystallization and evolution history of the alkaline melt as well as its origin. The rock series hosting t MoreClinopyroxene phenocrysts and microphenocrysts in potassic and sodic Eosen alkaline volcanic rocks from the northern Lahrud (NW Iran) record various stages in the crystallization and evolution history of the alkaline melt as well as its origin. The rock series hosting the clinopyroxene phenocrysts is phonolitic tephrite and tephritic phonolite composition. Theses rocks generally show porphyritic texture and have a variable phenocryst-rich nature (25–50%), with phenocryst assemblages characterized by Cpx ± An ± Pl. The studied clinopyroxenes have relatively high Mg-numbers (0.66-0.90), variable Al2O3 (3.77-7.31 wt%), low TiO2 (<2.02 wt%) and Na2O (<1.23 wt%) contents and low AlVI/AlIV ratios (mostly <0.25), suggesting relatively low-pressure crystallizing conditions of the magma in the magma chamber. The calculated pressures for the clinopyroxenes in these rocks vary in the range of 4–5.5 kbars. Oscillatory reverse zoning of clinopyroxenes related to the different crystallization paths under a variable oxygen fugacity and different oxidation conditions and sudden pressure differentiation and magma mixing processes. Normal zoning related to the differentiation and fractional crystallization of the magma. The resorption texture of core parts of some clinopyroxenes are attributed to the changes of crystallization pressure though such textures have been ascribed to magma mixing. Manuscript profile -
Open Access Article
8 - Mineralogy and Geochemistry Studies of the Sorkheh Sediment-hosted Stratiform Copper (SSC) Deposit, NW Iran
Shohreh Hassanpour Saeedeh SenemariOre-stage sulfides are zoned vertically and obliquely through the mineralized zones, from cupriferous sulfides at low stratigraphic levels to copper-rich mineralization above, with unreplaced pyrite remaining within the upper Miocene. The zoned sulfides and their replac MoreOre-stage sulfides are zoned vertically and obliquely through the mineralized zones, from cupriferous sulfides at low stratigraphic levels to copper-rich mineralization above, with unreplaced pyrite remaining within the upper Miocene. The zoned sulfides and their replacement textures, configuration of the mineralized zones, and the position of ore stage mineralization adjacent to a stratigraphically defined redox transition from red beds upward into graybeds indicate an overprint of copper (and accompanying ore-stage metals) on originally pyritic gray beds. The influx of ore-stage metals, presumably in an oxidized low-temperature brine, terminated with a silicification event that effectively sealed the host sandstones. Consequently, these observations and the overall genetic interpretation are consistent with the general deposit-scale genetic model for early diagenetic SSC mineralization. The regional geologic context is also consistent with its classification as a SSC deposit and is hosted by sediments that were formed in association with evaporates at a low latitude in a Sabkha environment. Source of Sorkheh deposition has been indicated as a sedimentary arid type. Sandstones of the Sorkheh area tectonic settings are obtained in a passive continental margin. Manuscript profile
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