A. Bahrampour; Gh. Ghadami; H. Atapour; M. Poosti; H. Ahmadipour
Abstract
At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites ...
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At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites and sanaite. Olivine, clinopyroxene, plagioclase and potassium feldspar are the main minerals in all two groups. Mineral chemistry shows that olivines, clinopyroxenes and amphiboles are of chrysolite (Fo = 72.35-79.85)), augite (Wo = 44.3-50.2, En= 37.06-44.4, Fs = 9.24-14.6), and kaersutite (Ca+Na = 2), (Na+K = 0.59-0.95), (Mg/(Mg+Fe2) = 0.63-0.76) composition, respecrively. Geobarometric and geothermometric estimations along with the tectonomagmatic diagrams for clinopyroxenes show that the parental magmas werealkaline in which the clinopyroxenes crystallized at pressure of 11-15 Kbar and temperature of 1150-1300 ◦C.Whole rock chemical analyses of these rocks show that the parental alkaline magma was originated from a metasomatized lithospheric garnet- spinel- lherzolite mantle source and emplaced in a post-collisional environment.
M Poosti; R Mohammadi Poortaziyani; H Hajhasani; S.M Mortazavi Ravari
Abstract
The LerdGarm peridotite complex is one of the ultramafic complexes in south-east Iran . This complex is composed mainly of harzburgite dunite, lherzolite, and secondary listvenite and magnesite. The detailed electron microprobe study revealed very high Cr # (39.9-64.0), Mg # (51.2-65.63) and very low ...
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The LerdGarm peridotite complex is one of the ultramafic complexes in south-east Iran . This complex is composed mainly of harzburgite dunite, lherzolite, and secondary listvenite and magnesite. The detailed electron microprobe study revealed very high Cr # (39.9-64.0), Mg # (51.2-65.63) and very low TiO2 content (averaging 0.05 wt %) for chromian spinels in peridotites. The Fe3+# is very low (C± 60 at a pressure of 26 Kbar. Tectonic environment discrimination diagrams for dunites show a suprasubduction environment of the arc setting and for the harzburgite and lherzolites show abyssal environment.
Gh Ghadami; M Poosti; F Babai
Abstract
Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts ...
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Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts of plagioclase, amphiboles and biotites. Based on geochemical data and multi elements patterns, these rocks are medium to high K calc-alkaline suite and they show LILE and LREE enriched normalized multi-element patterns, and negative Nb, Ti and Ta anomalies. Chondrite normalized REE patterns display a steep decrease from LREE to HREE without any Eu anomaly. They have higher SiO2 and Sr contents and Sr/Y and La/Yb ratios and low MgO, Y and Yb contents than the normal calc-alkaline volcanic rocks. These volcanic rocks are formed in the a subduction zone in an active margin, and showing full complete of HSA(high SiO2 adakites) characteristics. HREE and Y depleted patterns suggest the existence of garnet and amphibole as a residue in the source. The source of these rocks was probably amphibole-eclogite or garnet-amphibolite possibly generated during subduction or slab break of the Neo-Tethyan oceanic slab beneath the Central Iran microplate in Neogene.
M Poosti; M Fadaeian
Abstract
The study area is located in the Ardabil province and in the north of Meshkin shahr town. A large part of the areais formed of Eocene igneous rocks. These rocks include basaltic andesite, basalt, tephrite and occasionally analcimite. They are silica saturated or relatively saturated. ...
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The study area is located in the Ardabil province and in the north of Meshkin shahr town. A large part of the areais formed of Eocene igneous rocks. These rocks include basaltic andesite, basalt, tephrite and occasionally analcimite. They are silica saturated or relatively saturated. According to tectonomagmatic diagrams, the original setting of the parental magma was a volcanic arc and subduction zone. The negative anomalies of Nb, the high ratio of LILE/HFSE, the high mounts of Al2O3& P2O5, the low titanium contents, and the degree of partial melting of the metasomatized upper mantle, strengthens the subduction related processes for the formation of the primary magma (alkali olivine basalt). Petrographic evidences suggest that the primary magma is mixed with crustal materials. The chemical composition of rocks, according to geochemical diagrams, is shoshonitic. These rocks may have been formed by the subduction of the oceanic crust of Neoteties during the Mesozoic and early Cenozoic periods. Releasing fluids exerted from the subducting slab, metasomatism of the lithospheric mantle and subsequently the appropriate conditions for melting of the metasomatized mantle, all led to the formation of potassic magmatism and finally, generation of magma with a shoshonitic nature found its way to the surface under the influence of an extension phase and complex fault systems.
