Conference Presentations by Hamid Ahmadipour
Ministry of industries and mines geological survey of Iran, 206-207, 2006
Papers by Hamid Ahmadipour
Turkish Journal of Earth Sciences, 2023
journal of sciences islamic republic of iran, 2020
The mantle peridotites of the Hadji-Abad ultramafic complex in Hormozgan province, show some petr... more The mantle peridotites of the Hadji-Abad ultramafic complex in Hormozgan province, show some petrological evolutions of the upper mantle of southern Iran. The complex includes harzburgite, lherzolite, dunite and chromitite. Evidences such as different generations of minerals, lobate boundaries between grains, elongation of cr-spinels and pyroxenes, incongruent melting related textures and exsolution lamellae of clinopyroxene in orthopyroxene show that the rocks in this complex first underwent high temperature-pressure in the upper mantle, and then emplaced in the crust. The chemical composition of chromites in the Hadji Abad dunites and chromitites is similar to that of boninite melts, while, the mineral chemistry of the harzburgitic and lherzolitic show that the host peridotites belong to the upper mantle and have been depleted from incompatible elements due to 15 to 20 percent partial melting. Geo-thermometric calculations reveal that the studied peridotites equilibriated in upper...
Ore Geology Reviews, 2015
Abstract The Abdasht complex is a major ultramafic complex in south-east Iran (Esfandagheh area).... more Abstract The Abdasht complex is a major ultramafic complex in south-east Iran (Esfandagheh area). It is composed mainly of dunite, harzburgite, podiform chromitites, and subordinate lherzolite and wehrlite. The podiform chromitites display massive, disseminated, banded and nodular textures. Chromian spinels in massive chromitites exhibit a uniform and restricted composition and are characterized by Cr# [= Cr / (Cr + Al)] ranging from 0.76 to 0.77, Mg# [= Mg/(Mg + Fe 2 + )] from 0.63 to 0.65 and TiO 2 2 contents (averaging 0.07 wt.%). The Fe 3 + # is very low, ( The distribution of platinum group elements (PGE) in Abdasht chromitites displays a high (Os + Ir + Ru)/(Rh + Pt + Pd) ratio with strongly fractionated chondrite-normalized PGE patterns typical of ophiolitic chromitites. Moreover, the Pd/Ir value, which is an indicator of PGE fractionation, is very low ( The harzburgite, dunite and lherzolite samples are highly depleted in PGE contents relative to chondrites. The Pd N /Ir N ratios in dunites are unfractionated, averaging 0.72, whereas the harzburgites and lherzolites show slightly positive slopes PGE spidergrams, together with a small positive Ru anomaly, and their Pd N /Ir N ratio averages 2.4 and 2.3 respectively. Moreover, the PGE chondrite and primitive mantle normalized patterns of harzburgite, dunite and lherzolite are relatively flat which are comparable to the highly depleted mantle peridotites. The mineral chemistry data and PGE geochemistry indicate that the Abdasht chromitites and peridotites were generated from a melt with boninitic affinity under low oxygen fugacity in a supra-subduction zone setting. The composition of calculated parental melts of the Abdasht chromitites is consistent with the differentiation of arc-related magmas.
Ore Geology Reviews, 2015
Abstract: Changes assessment of Sr-Nd ratios and some rare elements at Mt.Bidkhan showed that... more Abstract: Changes assessment of Sr-Nd ratios and some rare elements at Mt.Bidkhan showed that the eruptive products are belong to a subduction environment. It seems that the magma at bidkhan volcano has a metasomatised slab heritage or has a partial melted lithosphere with crustal melt heritage that move upward and influenced with crystallization, contamination phenomena. The influence of crustal contamination is very clear on isotopic ratios and it may due to the stopping of magma or injection of materials from lithosphere to mantle slab or melting of mestasomatic mantle. Keywords: Bidkhan,Contamination,Sr-Nd,Rare element,Magma,Metasomatise
Mount Bidkhan stratovolcano is located in the Central Iranian Volcanic Belt and contains Pliocene... more Mount Bidkhan stratovolcano is located in the Central Iranian Volcanic Belt and contains Pliocene high-K calcalkaline andesitic and dacitic volcanics. These volcanics contain non-equilibrated phenocrysts such as Clinopyroxene, Orthopyroxene, plagioclase, hornblend, biotite and quartz. Clinopyroxene are mainly diopside and augite in composition. They show distinctive chemical zoning, that is, in core, they are rich in Ca relative to their rim. In these minerals, Mg# values change between 0.6 to 0.8 and Al2O3 content between 1 to 10. Bidkhan Orthopyroxene are hypersthene composition .Their Mg# values vary between 0.70 and 0.78. Whole rock analysis of Bidkhan andesitic rocks indicate that in these rocks, the average amounts of SiO2, MgO, and Al2O3 are 59% , 1%, 16.5% respectively, while those in dacitic rocks are 65%, 2%,7%. Sakuyama (1984)[1], Costa et al (2002) and others believe that magmas with these compositions can not directly crystallize those Cpx and Opx which are found in Bid...
Abstract Mt. Bidkhan is a stratovolcano and has located in the South Western part of Kerman provi... more Abstract Mt. Bidkhan is a stratovolcano and has located in the South Western part of Kerman province. We can find some Mingling and mixing features in Bidkhan Andesitic and Dacitic rocks. At least 5 types of disequilibrium texture found in Bidkhan Plagioclases .An mol% at the core of plagioclases are very different from the margins. These evidences led us to conclude that Magma mingling has occurred during eruption. According to whole evidence we propose that it is likely that a basic melt injected to the lower crust and has mixed with some acidic magma to made eruptive products of Mt.Bidkhan
Mount Bidkhan stratovolcano is located in the central Iranian volcanic belt. It is composed of se... more Mount Bidkhan stratovolcano is located in the central Iranian volcanic belt. It is composed of several types of pyroclastic deposits, lava flows and intrusive bodies. Textural and chemical characteristics of plagioclase phenocrysts from the eruptive products volcanic edifice, record complex magma mixing events over the lifetime of the volcano. Evidences such as xenocrystic high Al+Ti clinopyroxene and calcic cored plagioclase phenocrysts (An 75) in andesites, sieve-textured, dusty, and oscillatory zoned plagioclase together with clear normally zoned ones in the same sample and the wide compositional range of the plagioclase rims, show that magma mixing events have been playing an important role in the origin of Bidkhan eruptive products . Based on whole evidences, we propose a model for the evolution of Bidkhan parent magmas. According to the model, it is likely that mantle derived basic melts are injected into the lower crust, cause partial melting and produced acidic primitive mel...
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Conference Presentations by Hamid Ahmadipour
Papers by Hamid Ahmadipour