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1 - Clinopyroxen mineral chemistry for evaluation of temprature - pressure and genesis of matasomatic basaltic rocks of the Hormuz Formation in Gachin and Hormoz Island salt domes, south of Iran
Roghayeh Nemati Ali Kananian MohamadAli Makizadeh Sedigheh Taghipour

Gachin and Hormoz island salt domes are composed of the Hormoz Formation and both are located in Hormozgan province and folded Zagros zone. Based on petrography, minerals of basaltic rocks formed in two stages: first magmatic minerals include in quartz, feldspar, pyrox More

Gachin and Hormoz island salt domes are composed of the Hormoz Formation and both are located in Hormozgan province and folded Zagros zone. Based on petrography, minerals of basaltic rocks formed in two stages: first magmatic minerals include in quartz, feldspar, pyroxene, amphibole, and then metasomatic minerals: tremolite - actinolite, chlorite, epidote, calcite, biotite, albite and iron oxide. Metasomatism changed rock forming minerals but most of clinopyroxenes are fresh compared to other minerals. Mineral chemistry of clinopyroxene is used for recognition of magma nature and tectonic settings of parent magma of the Hormoz Formation. The average composition of clinopyroxens of Gachin salt dome is augite (Wo27.66 En45.44 Fs26.91), clonopyroxens of Hormoz Island salt dome is augite –diopsid (Wo43.36 En32.71Fs23.93). These minerals are Ca-Eskola. Geochemical diagrams based on clynopyroxens composition show that the background of Hormoz salt dome samples are volcanic arc basalts and Gachin salt dome samples are intraplate tholeiitic basalts and they had sub-alkaline nature. Their forming temperatures of clinopyroxens are 875oc for Hormoz clinopyroxenes and 997oc for Gachin clinopyroxenes and forming pressure is less than 2kb. Manuscript profile
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2 - 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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3 - Geochemical study of the soils provenance of The Gysian-Silvana-Urmia ophiolitic region
zainab sadeghi Hossein Pirkharrati monir modjarrad Reza dehbandi

Gysian ophiolite is a remnant of the Neotethys, located in the north-west Iran at the intersection of the ophiolite belts of south-eastern Turkey, north-eastern Iraq and north-western Iran. The geochemical comparison of the soils with the average of global rocks and the More

Gysian ophiolite is a remnant of the Neotethys, located in the north-west Iran at the intersection of the ophiolite belts of south-eastern Turkey, north-eastern Iraq and north-western Iran. The geochemical comparison of the soils with the average of global rocks and the study area led to determination of the composition group of the region soils. The geochemical evidence of the first group of soil samples with low silica percentage by Harker and triangular diagrams is close to the position of ultramafic rocks of the region (serpentenites) and primary mantle and expresses their compositional similarity. The second group of soils ranges in the area between the earth's crust and basalt, and they show more distribution near basalt. The normalized pattern of REE rare earth elements in this group of soils is similar to the mafic rocks pattern in the region, also in the minor elements chart, they classified in the mafic group. Soils with high percentage of silica in the diagram of major and minor element oxides are located near the positiion of meta-plates rocks in the region, in the range between the earth's crust and global shale. So, this suggests the intermediate composition of their origin. Most likely, the tectonic setting of the three soil groups is based on the oxides of the main elements of the active continental margin. Manuscript profile

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List of Articles محیط تکتونیکی