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1 - The Study of alteration, mineralization, and fluid inclusion in the Howz-e-Sefid zinc-lead deposit (Central Iran)
Mansor Adelpour godratollah Rostami Paydar

The Howz-e-sefid zinc-lead deposit is located 17 km northeast of Ardakan town in the central Iran tectonic zone. Host rock of this deposit is lower Cretaceous dolomitized carbonate rocks. In this area there are three major rock units. The Sangestan Formation as the lowe More

The Howz-e-sefid zinc-lead deposit is located 17 km northeast of Ardakan town in the central Iran tectonic zone. Host rock of this deposit is lower Cretaceous dolomitized carbonate rocks. In this area there are three major rock units. The Sangestan Formation as the lowest unit, is composed of shale and siltstone with calcarenitic interbeded layers. This unit is overlain by ankeritic massive dolomite and dolomitic limestone of the Taft Formation. The Abkouh Formation at the top, is composed of cherty or argillaceous limestone with massive reefal limestone. The host rock of deposit in the lower Cretaceous carbonate horizon along with other geological evidence indicate that this deposit has been primarily formed similar to the Mississipi Valley-type deposits. This conditions include carbonate and evaporatic sequences, special hydrothermal dolomitized horizons, lack of the effects of igneous intrusions and the presence of the important controling faults. Based on the observations, it can be concluded that the primary ores have been of the sulphide type including sphalerite, galena and pyrite. Due to their exposure to superficial oxidizing conditions and undergoing changes, the primary sulphide ores, have been converted into nonsulphide ore body. As a result, the primary sulphide ores have been changed into secondary minerals such as hemimorphite, smithsonite, cerusite and anglesite. In many cases, the nonsulphide minerals established in the structural fractures and fissures, shows the colloform texture. Therefore, it can be accepted that this type of minerals were formed under the effect of low temperature hydrothermal fluids.There are two types of fluid inclusions (type I: L and type II: L+V) in the carbonaceous ore bearing veins. On the basis of microthermometric study, the homogenization temperatures is between 150-260 °C. The salinity of fluid inclusions is low to intermediate (0.33-14.26 wt. % NaCl equivalent). Heating depressurization due to reduced pressure to boiling with low CO2 bearing fluid (0.62-0.98 gr/cm3) is the main mechanism of deposition. Based on evidence such as the nonhomoginity in filling degree of fluid inclusions, existence of a few vapor-rich phase shows boiling of ore fluid in faulted and fracture zones. Manuscript profile
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2 - Late Cretaceous Island-arc subduction magmatism in northern edge of central Iran, SW Sabzevar
Elham Mirzakazemi Habibollah Ghasemi Fardin Mousivand Wilyam Griffin

A thick sequence of Late Cretaceous volcano-sedimentary rocks crops out on the northern margin of Central Iran, in the southwest of the Sabzevar. The igneous rocks include extrusions (trachy-andesite, dacite and rhyolite) and shallow depth intrusions (gabbro, gabbrodior More

A thick sequence of Late Cretaceous volcano-sedimentary rocks crops out on the northern margin of Central Iran, in the southwest of the Sabzevar. The igneous rocks include extrusions (trachy-andesite, dacite and rhyolite) and shallow depth intrusions (gabbro, gabbrodiorite, diorite and granite). These igneous rocks have geochemical signatures of magmatic rocks of island-arc subduction zones and plot within field in different tectonic setting discrimination diagrams. The parental magma of these rocks has island arc tholeiitic nature and was produced via partial melting of a depleted spinel lherzolite mantle source during closing of the Sabzevar Neo-Tethyan oceanic basin in the Late Cretaceous. This depleted mantle source was affected by the metasomatic fluids released from dehydration of the Neo-Tethys subducted oceanic slab. Manuscript profile
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3 - Geochemistry and petrology of Qareh-Dash rhyolites from Shahindej- NW Iran: Geochemical features of post- collision volcanism
Masoumeh Ahangari معصومه نظری Mohsen Moazzen
20.1001.1.17357128.1399.14.56.4.7

Qareh-Dash rhyolites from the Shahindej area are peraluminous rocks with high SiO2 and K2O contents. These rocks are mainly composed of quartz, K- feldspar and rare plagioclase phenocrysts in a fine-grained K-feldspar rich matrix. Geochemically, Qareh-Dash rhyolites sho More

Qareh-Dash rhyolites from the Shahindej area are peraluminous rocks with high SiO2 and K2O contents. These rocks are mainly composed of quartz, K- feldspar and rare plagioclase phenocrysts in a fine-grained K-feldspar rich matrix. Geochemically, Qareh-Dash rhyolites show enrichment in LREEs and LILEs and depletion in HREEs. Field studies, textural and petrographical relations, along with whole rock geochemistry, demonstrate that the parental magma of the Qareh-Dash rhyolites was originated from the crust. The composition of the parental magma was modified due to fractional crystallization of plagioclase and titanomagnetite evidenced by negative Eu, Sr and Ti anomalies in multielement diagrams. The chemical characteristics of Qareh- Dash rhyolites such as Rb/Nb, K/Rb, Rb/Sr, Rb/Ba and Ga/Al ratios are similar to A-Type granites/ rhyolites associated with post- collision tectonic settings. According to Precambrian age for the Qareh-Dash rhyolites, formation of these rocks might be related to extensional phases which were probably taken place after closure of proto- Thetys Ocean. Manuscript profile
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4 - Geology, mineralization, mineralogy, structure and texture in the Ghezeljeh Cu, Pb-Zn deposit, NW Zanjan
Seyedeh Aliyeh Seyedeh Aliyeh Ghasem Nabatian Afshin Zohdi Armin Salsani
20.1001.1.17357128.1402.17.65.4.6

Ghezeljeh deposit is located in the Central Iranian zone, in the Zanjan province and northeast of the Mahneshan city. The rock units in this area belongs to the Oligo-Miocene, which contain Lower Red, Qom and Upper Red formations. The Upper Red Formation in Ghezeljeh re More

Ghezeljeh deposit is located in the Central Iranian zone, in the Zanjan province and northeast of the Mahneshan city. The rock units in this area belongs to the Oligo-Miocene, which contain Lower Red, Qom and Upper Red formations. The Upper Red Formation in Ghezeljeh region has about 750 m thickness and mainly consists of brown to green marl intercalations with sandstones. In this area, the alternation of marl and sandstone sequences contain sandstone layers with thickness about 2 to 8 meters, which in two horizons, the copper-lead and zinc mineralization has occurred. Copper mineralization, in addition to being observed inside the sandstone unit. In the Ghezeljeh deposit, the host rocks of the copper ores, are gray sandstones and conglomerates which are intercalated with red and gray marl units. According to field and microscopic studies, the main ore mineral consist of pyrite, chalcocite, chalcopyrite, bornite, galena and sphalerite which associated with the secondary minerals such as serosite, malachite, azurite, covellite, smithzonite and goethite. The ore mineral textures consist of disseminate, framboidal pyrite, solution seams, interparticle cement, replacement and relict. Preliminary fieldwork studies in the Ghezeljeh region also show that organic matter including plant remains and diagenetic pyrite are the effective factors to concentrate and mineralization. It is considerable that the grade of lead, zinc and copper, in Ghezeljeh deposit are 6%, 3% and 1%, respectively. Generally, host rock, tectonic setting, sedimentary environment, mineralogy, texture, mineralization control factors all confirm that the studied mineralization has more similarities with Redbed type copper deposits. Manuscript profile
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5 - A new look at the rotation of Central Iran: A case study of the Anar fault, east block of the Yazd
Hamidreza AfkhamiArdakani farzin ghaemi Fariba Kargaran Bafghi Ahad Nouri

The Anar fault in the east of Yazd city, with a north-northwest-south-southeast strike, is a basement fault that separates the Yazd block from the Posht Badam block, and its current activity is a dextral strike-slip with a reverse component. The paleostress analysis was More

The Anar fault in the east of Yazd city, with a north-northwest-south-southeast strike, is a basement fault that separates the Yazd block from the Posht Badam block, and its current activity is a dextral strike-slip with a reverse component. The paleostress analysis was done on this fault in order to obtain the tectonic history of central Iran in the period from Devonian to Cretaceous. After analyzing 110 fault data in 13 stations of 2 tectonic phases, it was determined that the maximum stress obtained is between the azimuths of 90 to 110 and 190 to 220 and the angle of stress direction changes in the period from Devonian to Cretaceous is 130 degrees. Based on the studies on the barite veins and the dextral displacements that were seen on them, the separation of the stress phases was done, which indicates that the NNE stress direction is older. Further, according to the previous studies of sedimentology and tectonics in central Iran, it was concluded that the cause of this change in tension was the movement towards the northeast along with the 130 degree counter-clockwise rotation of central Iran. Manuscript profile

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