University of IsfahanPetrological Journal2228-52102720110522Causes of different composition of chromitites in Naein and Ashin ophiolites, and its absence in Anark and Jandaq ophiolites (Isfahan province)Causes of different composition of chromitites in Naein and Ashin ophiolites, and its absence in Anark and Jandaq ophiolites (Isfahan province)12016077FAGhodratTorabiJournal Article20160614There are two types of ophiolites in the west of Central Iran: Mesozoic ophiolites (Naein and Ashin), and Paleozoic or Precambrian ophiolites (Anarak and Jandaq). Field studies show that the Mesozoic ophiolites have considerable masses of chromitite, but there are no chromitite Anarak and Jandaq ophiolites. The study of Mesozoic ophiolites reveals that they have two different types of chromitites. The Naein chromitites are high-Cr whereas the Ashin chromitites are high-Al. The reasons for the chromitite absence in the Anarak and Jandaq ophiolites are lherzolitic system of mantle, low degree of partial melting in mantle rocks and the lack of sequential melt production by mantle. Different composition of orthopyroxenes, difference in degree of partial melting and chemistry of ascending melts are causes of compositional diversity of chromitites in Mesozoic ophiolites.There are two types of ophiolites in the west of Central Iran: Mesozoic ophiolites (Naein and Ashin), and Paleozoic or Precambrian ophiolites (Anarak and Jandaq). Field studies show that the Mesozoic ophiolites have considerable masses of chromitite, but there are no chromitite Anarak and Jandaq ophiolites. The study of Mesozoic ophiolites reveals that they have two different types of chromitites. The Naein chromitites are high-Cr whereas the Ashin chromitites are high-Al. The reasons for the chromitite absence in the Anarak and Jandaq ophiolites are lherzolitic system of mantle, low degree of partial melting in mantle rocks and the lack of sequential melt production by mantle. Different composition of orthopyroxenes, difference in degree of partial melting and chemistry of ascending melts are causes of compositional diversity of chromitites in Mesozoic ophiolites.https://ijp.ui.ac.ir/article_16077_3ccf4aeb7d66bfdfa3f75bbe8d5a3c73.pdfUniversity of IsfahanPetrological Journal2228-52102720110522Mineralization study of titanium in Kahnouj ophiolitic complex based on petrological, mineralogical and geochemical data, south of Kerman provinceMineralization study of titanium in Kahnouj ophiolitic complex based on petrological, mineralogical and geochemical data, south of Kerman province213816078FAMohammad AliRajabzadehشیراز- چهار راه ادبیات- دانشکده علوم-بخش علوم زمینMansourGhorbaniMonirSaadatiJournal Article20160614The Kahnouj ophiolitic complex, in south of Kerman Province emplaced as a horst structure between two major north-south trending fault zones of Jiroft and Sabzevaran. The ophiolite is incomplete and is composed mainly of layered gabbros, isotropic gabbros, sheeted dykes, plagiogranites as well as pillow lavas associated with radiolarites and pelagic limestones. Ilmenite is the predominant Ti-bearing mineral often occurred as interstitial with amphibole following plagioclase, olivine and clinopyroxene crystallization. The formation of considerable gabbro masses accompanied by crystallization of large amounts of plagioclase and clinopyroxene leads to the differentiation of Ti-Fe-rich melts at ferrogabbro formation as major ilmenite host rock. Decrease in compatible elements such as Mg and Cr and continuous increase in incompatible elements (e. g. Mn, Na and Ti) from the lower towards the upper parts of the ophiolitic complex indicate that the ophiolitic rocks crystallized from Ti-rich tholeiitic magma during fractional crystallization.The Kahnouj ophiolitic complex, in south of Kerman Province emplaced as a horst structure between two major north-south trending fault zones of Jiroft and Sabzevaran. The ophiolite is incomplete and is composed mainly of layered gabbros, isotropic gabbros, sheeted dykes, plagiogranites as well as pillow lavas associated with radiolarites and pelagic limestones. Ilmenite is the predominant Ti-bearing mineral often occurred as interstitial with amphibole following plagioclase, olivine and clinopyroxene crystallization. The formation of considerable gabbro masses accompanied by crystallization of large amounts of plagioclase and clinopyroxene leads to the differentiation of Ti-Fe-rich melts at ferrogabbro formation as major ilmenite host rock. Decrease in compatible elements such as Mg and Cr and continuous increase in incompatible elements (e. g. Mn, Na and Ti) from the lower towards the upper parts of the ophiolitic complex indicate that the ophiolitic rocks crystallized from Ti-rich tholeiitic magma during fractional crystallization.https://ijp.ui.ac.ir/article_16078_52e8a9b157d04ea078c7f19d09a1c867.pdfUniversity of IsfahanPetrological Journal2228-52102720110522Geochemistry and petrogenesis of Givshad volcanic and subvolcanic rocks (southwest of Birjand, east of Iran)Geochemistry and petrogenesis of Givshad volcanic and subvolcanic rocks (southwest of Birjand, east of Iran)395016079FAMohammad HosseinZarrinkoubبیرجند- دانشگاه بیرجند- دانشکده علوم گروهزمین شناسیSeyed SaeidMohammadiFazilatYousefiJournal Article20160614The study area is located 41 Km Southwest of Birjand, in the northern part of Sistan suture zone. An Eocene dioritic subvolcanic body together with andesites and basaltic andesites have intruded into the paleogene shales and sandstones. The main textures in these rocks are porphyric with microgranular groundmass, porphyric and glomeroporphyritic. Plagioclase (oligoclase-andesine) and amphibole (green hornblende) are the main phenocrysts. Biotite, clinopyroxene and rare olivine are the remaining minerals of these rocks. The negative anomaly in high field strength elements (HFSE) such as Nb and Ti in these rocks point to the geochemical characteristic of magmatic arcs. High ratio of LREE/HREE, Sr/Y (Ave. 44.33), La/Yb (Ave. 12.48), the amount of SiO2 and the absence of Eu negative anomaly show that these rocks are similar to adakites. On the base of obtained data, the magmatism can be the result of a post collision process in a subduction regime originated from an eclogite source.The study area is located 41 Km Southwest of Birjand, in the northern part of Sistan suture zone. An Eocene dioritic subvolcanic body together with andesites and basaltic andesites have intruded into the paleogene shales and sandstones. The main textures in these rocks are porphyric with microgranular groundmass, porphyric and glomeroporphyritic. Plagioclase (oligoclase-andesine) and amphibole (green hornblende) are the main phenocrysts. Biotite, clinopyroxene and rare olivine are the remaining minerals of these rocks. The negative anomaly in high field strength elements (HFSE) such as Nb and Ti in these rocks point to the geochemical characteristic of magmatic arcs. High ratio of LREE/HREE, Sr/Y (Ave. 44.33), La/Yb (Ave. 12.48), the amount of SiO2 and the absence of Eu negative anomaly show that these rocks are similar to adakites. On the base of obtained data, the magmatism can be the result of a post collision process in a subduction regime originated from an eclogite source.https://ijp.ui.ac.ir/article_16079_0bb758fa8a5fb475ca62f8eba1a25c2f.pdfUniversity of IsfahanPetrological Journal2228-52102720110522Petrology and mineral chemistry of Ochestan granitoids (south of Mahallat, Markazi province)Petrology and mineral chemistry of Ochestan granitoids (south of Mahallat, Markazi province)517416080FASeyed MohsenTabatabaiemaneshAkram SadatMirlohiMehriMovahediJournal Article20160614The Ochestan granitoids are located 60 Km South of Mahallat in Markazi province and in Sanandaj-Sirjan zone. Based on petrographic studies, these rocks are alkali feldspar-granite, granite (syenogranite and monzogranite) and granodiorite. Alkali feldspar (orthoclase and microcline), plagioclase (albite and oligoclase), quartz and muscovite are present as the major minerals and tourmaline, biotite, zircon, garnet, apatite, opaque minerals, rutile and chlorite as the secondary ones. Foliation is found in many parts of the pluton indicating mylonitization process. Geochemical studies show sub-alkaline (calc-alkaline), peraluminous and S-Type for the granitoid studied. According to spider diagrams, upper crust is considered as the magma source, and syncollision as the geotectonic setting. Partial melting of metapelites can be assumed as a source of magma generation in regard to the type of granitoids, geochemical data and metamorphic rocks exposing in this area.The Ochestan granitoids are located 60 Km South of Mahallat in Markazi province and in Sanandaj-Sirjan zone. Based on petrographic studies, these rocks are alkali feldspar-granite, granite (syenogranite and monzogranite) and granodiorite. Alkali feldspar (orthoclase and microcline), plagioclase (albite and oligoclase), quartz and muscovite are present as the major minerals and tourmaline, biotite, zircon, garnet, apatite, opaque minerals, rutile and chlorite as the secondary ones. Foliation is found in many parts of the pluton indicating mylonitization process. Geochemical studies show sub-alkaline (calc-alkaline), peraluminous and S-Type for the granitoid studied. According to spider diagrams, upper crust is considered as the magma source, and syncollision as the geotectonic setting. Partial melting of metapelites can be assumed as a source of magma generation in regard to the type of granitoids, geochemical data and metamorphic rocks exposing in this area.https://ijp.ui.ac.ir/article_16080_d438956e331b417d94431f2ae5197779.pdfUniversity of IsfahanPetrological Journal2228-52102720110522The Oligocene basaltic lavas of east and southeast of Shahroud: Implication for back-arc basin setting of Central Iran Oligo-Miocene basinThe Oligocene basaltic lavas of east and southeast of Shahroud: Implication for back-arc basin setting of Central Iran Oligo-Miocene basin779416081FAMohammadBarahmandMahmoudSadeghianJournal Article20160614Some basaltic lava, with olivine basalt to basaltic composition, have been erupted within the Oligocene gypsiferous red marls (Lower Red Formation), in east and southeast of Shahroud. These rocks display microlitic porphyry, glomeroporphyry and hyaloporphyry textures. Olivine, plagioclase and pyroxene (in olivine basalts) and plagioclase and pyroxene (in basalts) are the main minerals. Enrichment in LREE and LILE and depletion in HREE, with positive anomalies in Pb, Sr and Cs, and the absence of negative anomalies in Eu and HFSE, indicate an alkaline nature and a sub-lithospheric enriched mantle source for these rocks. The rocks studied plot in back-arc basin realm in petrogenetic and tectonomagmatic diagrams and seem to be generated from about 10% partial melting of an enriched garnet-lherzolitic mantle source. This tectonic setting, implies an extensional proto-back-arc basin in Oligo-Miocene, behind the Uroumiyeh-Dokhtar magmatic arc, in some parts of Central Iran, that had been accompanied by the deposition of continental sediments (Lower Red Formation), shallow sea deposits (Qom Formation) followed by continental sediments (Upper Red Formation) and basic alkaline mantle magmatism.Some basaltic lava, with olivine basalt to basaltic composition, have been erupted within the Oligocene gypsiferous red marls (Lower Red Formation), in east and southeast of Shahroud. These rocks display microlitic porphyry, glomeroporphyry and hyaloporphyry textures. Olivine, plagioclase and pyroxene (in olivine basalts) and plagioclase and pyroxene (in basalts) are the main minerals. Enrichment in LREE and LILE and depletion in HREE, with positive anomalies in Pb, Sr and Cs, and the absence of negative anomalies in Eu and HFSE, indicate an alkaline nature and a sub-lithospheric enriched mantle source for these rocks. The rocks studied plot in back-arc basin realm in petrogenetic and tectonomagmatic diagrams and seem to be generated from about 10% partial melting of an enriched garnet-lherzolitic mantle source. This tectonic setting, implies an extensional proto-back-arc basin in Oligo-Miocene, behind the Uroumiyeh-Dokhtar magmatic arc, in some parts of Central Iran, that had been accompanied by the deposition of continental sediments (Lower Red Formation), shallow sea deposits (Qom Formation) followed by continental sediments (Upper Red Formation) and basic alkaline mantle magmatism.https://ijp.ui.ac.ir/article_16081_dabcb82617ad44e26a5910bab5c2583a.pdfUniversity of IsfahanPetrological Journal2228-52102720110522U-Pb-Th (zircon) geochronology, Sr and Nd isotopic composition and petrogenesis of granitoid pebbles of Qara Gheitan conglomerate, Aghdarband area, northeast IranU-Pb-Th (zircon) geochronology, Sr and Nd isotopic composition and petrogenesis of granitoid pebbles of Qara Gheitan conglomerate, Aghdarband area, northeast Iran9511816076FAMohammad HassanKarimpourAzadehMalekzadeh Shafaroudi0000-0002-7373-561xFarzinGhaemiG. LangFarmerCharlesSternJournal Article20160614The Qara Gheitan conglomerate (Late Permian-Early Triassic), is a part of Kopeh Dagh basement, situated in Aghdarband, northeast of Iran. The plutonic pebbles of conglomerate predominantly contain granite, alkali-granite and minor monzonite. Granitoids are highly potassic and strongly per to metaluminous nature. Magnetic susceptibility of granitoids are between 2-27Ã10-5 (SI units), chemical and mineralogical composition indicate that they belong to ilmenite-series (reduced type) granitoids. The results of U-Pb zircon age dating of the granitoids pebbles are 343 Ma (Carboniferous). They have a range of initial 87Sr/86Sr from 0.7062 to 0.7068, 143Nd/144Nd initial between 0.511938- 0.511936, initial εNd isotope values from -5.03 to -4.99 when recalculated to an age of 343 Ma (zircon age). These values could be considered as representative of continental crust-derived magmas. Based on 143Nd/144Nd and εNd isotope values, the meta-sedimentary source rock had a minimum age of 1400 Ma. Within the core of some zircons, there are rounded zircons with an age of, 1986, 1039 and 645 Ma. These zircons were brought with magma from the source rock. At the time of formation of source rock, rocks from Proterozoic were exposed. When compare the age of Dehnow-Kuhsangi and Khajeh Mourad granitoids (reduced S-Type) formed (Late Triassic) due to collision of Turan and Iran plates with the age of granitoid pebble (Carboniferous), it seems that the pebbles are the results of the much older continental collision taking place somewhere in their formation site (in the north of Aghdarband possibly in Turkemenistan).The Qara Gheitan conglomerate (Late Permian-Early Triassic), is a part of Kopeh Dagh basement, situated in Aghdarband, northeast of Iran. The plutonic pebbles of conglomerate predominantly contain granite, alkali-granite and minor monzonite. Granitoids are highly potassic and strongly per to metaluminous nature. Magnetic susceptibility of granitoids are between 2-27Ã10-5 (SI units), chemical and mineralogical composition indicate that they belong to ilmenite-series (reduced type) granitoids. The results of U-Pb zircon age dating of the granitoids pebbles are 343 Ma (Carboniferous). They have a range of initial 87Sr/86Sr from 0.7062 to 0.7068, 143Nd/144Nd initial between 0.511938- 0.511936, initial εNd isotope values from -5.03 to -4.99 when recalculated to an age of 343 Ma (zircon age). These values could be considered as representative of continental crust-derived magmas. Based on 143Nd/144Nd and εNd isotope values, the meta-sedimentary source rock had a minimum age of 1400 Ma. Within the core of some zircons, there are rounded zircons with an age of, 1986, 1039 and 645 Ma. These zircons were brought with magma from the source rock. At the time of formation of source rock, rocks from Proterozoic were exposed. When compare the age of Dehnow-Kuhsangi and Khajeh Mourad granitoids (reduced S-Type) formed (Late Triassic) due to collision of Turan and Iran plates with the age of granitoid pebble (Carboniferous), it seems that the pebbles are the results of the much older continental collision taking place somewhere in their formation site (in the north of Aghdarband possibly in Turkemenistan).https://ijp.ui.ac.ir/article_16076_8e5c52bebd8e9cdea261ffe4ddfaf13b.pdfUniversity of IsfahanPetrological Journal2228-52102720110522Elements variations and the origin of fluids during the hydrothermal alterations in the Astaneh-Arak granitoidElements variations and the origin of fluids during the hydrothermal alterations in the Astaneh-Arak granitoid11913416082FARahimehMikailiMoussa KalimiNoghreyanدانشگاه اصفهان- دانشکده علوم - گروه زمین شناسیMohammad AliMackizadehBatoulTaghipourJournal Article20160614Seven distinct hydrothermal alteration zones developed within the Astaneh granitoid. The phyllic and silicic alterations have a wide extension in the study area. In the phyllic alteration, La in comparison to other REE's, is much more enriched which may be the result of sericite formation. The enrichment of LREE in the propylitic alteration, due to their accommodation in secondary minerals, is more than that of unaltered sample. The REE normalized pattern in the argillic alteration shows a considerable leaching of REE during the alteration process. The Eu/Eu* ratio in the altered samples is less than one and in comparison to unaltered sample displays positive anomaly. Generally, the chondrite normalized pattern in altered and unaltered sample is similar. The stable isotopes, δO18 and δD, data indicate that magmatic-metamorphic waters were responsible for fluids involved in phyllic and silicic alterations.Seven distinct hydrothermal alteration zones developed within the Astaneh granitoid. The phyllic and silicic alterations have a wide extension in the study area. In the phyllic alteration, La in comparison to other REE's, is much more enriched which may be the result of sericite formation. The enrichment of LREE in the propylitic alteration, due to their accommodation in secondary minerals, is more than that of unaltered sample. The REE normalized pattern in the argillic alteration shows a considerable leaching of REE during the alteration process. The Eu/Eu* ratio in the altered samples is less than one and in comparison to unaltered sample displays positive anomaly. Generally, the chondrite normalized pattern in altered and unaltered sample is similar. The stable isotopes, δO18 and δD, data indicate that magmatic-metamorphic waters were responsible for fluids involved in phyllic and silicic alterations.https://ijp.ui.ac.ir/article_16082_89f4bdfe4e4b15dfd76ae4284d8312f0.pdf