Hamid Ahmadipour

Shahid Bahonar University of Kerman, Carmana, Kermān, Iran

Are you Hamid Ahmadipour?

Claim your profile

Publications (18)3.38 Total impact

  • A.R. Najafzadeh, H. Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: The podiform chromite deposit of the Soghan mafic–ultramafic complex is one of the largest chromite deposits in south-east Iran (Esfandagheh area). The Soghan complex is composed mainly of dunite, harzburgite, lherzolite, pyroxenite, chromitite, wehrlite and gabbro. Olivine, orthopyroxene, and to a lesser extent clinopyroxene with highly refractory nature, are the primary silicates found in the harzburgites and dunites. The forsterite content of olivine is slightly higher in dunites (Fo94) than those in harzburgites (Fo92) and lherzolites (Fo89). Chromian spinel mainly occurs as massive chromitite pods and as thin massive chromitite bands together with minor disseminations in dunites and harzburgites. Chromian spinels in massive chromitites show very high Cr-numbers (80–83.6), Mg-numbers (62–69) and very low TiO2 content (averaging 0.17 wt.%) for which may reflect the crystallization of chromite from a boninitic magma. The Fe3 +-number is very low, down to < 0.04 wt.%, in the chromian spinel of chromitites and associated peridotites of the Soghan complex. PGE contents are variable and range from 80 to 153 pbb. Chromitites have strongly fractionated chondrite-normalized PGE patterns, which are characterized by enrichments in Os, Ir and Rh relative to Pt and Pd. Moreover, the Pd/Ir value which is an indicator of PGE fractionation ranges from < 0.08 to 0.24 in chromitite of the Soghan complex. These patterns and the low PGE abundances are typical of ophiolitic chromitites and indicating a high degree of partial melting (about 20–24%) of the mantle source. Moreover, the PdN/IrN ratios in dunites are unfractionated, averaging 1.2, whereas the harzburgites and lherzolites show slightly positive slopes PGE spidergrams, together with a small positive Ru and Pd anomaly, and their PdN/IrN ratio averages 1.98 and 2.15 respectively. The mineral chemistry data and PGE geochemistry, along with the calculated parental melts in equilibrium with chromian spinel of the Soghan chromitites indicate that the Soghan complex was generated from an arc-related magma with boninitic affinity above a supra-subduction zone setting.
    Ore Geology Reviews 01/2014; 60:60–75. · 3.38 Impact Factor
  • Source
    Shahram Khalili Mobarhan, Hamid Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: 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
    7th National Geological Conference of Payam Noor University, Lorestan province, Iran; 11/2013
  • Source
    Dataset: aa
  • Source
    Sh. Khalili Mobarhan, H. Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: Mt. Bidkhan's volcanic rocks(South-east Iran) cover a compositional spectrum from andesite to dacite. A plot of K2O+Na2O Vs SiO2 suggests a medium to high calkalkaline for volcanic products. The geochemical trends of the Bidkhan volcanics are depicted through the use of the harker diagrams. Many of compositional arrays of Bidkhan samples are linear (e.g. Fe, Ca, Y) which support amagmatic differentiation in parental magmas. Some element arrays, however, are scattered (e.g. Ba, Sr, P) or curvilinear (e.g. Al, Na). These suggest that processes such as crystallization, and assimilation also probably operate in the magma chamber. In addition, some features such as high amounts of Th/Nb and Zr/Nb ratios in Bidkhan samples, suggest crustal contamination has been played an important role in the evolution of Bidkhan parental magmas. Field observations and whole rock chemistry for Bidkhan rocks suggest that the last melts that have differentiated and erupted from shallow magma chambers had been intermediate (probably andesitic) melts and have been repeatedly invaded by newly intermediate batches of magmas during differentiation. Then we have to search the traces of magma mixing in mineral chemistry, especially plagioclase crystals in the Bidkhan rocks. Bidkan's plagiclases can be divided in 4 category: 1) Normal zoned plagioclases, In this type, An mol% varies from 53 in core to 10 in the rim; 2) Reversely zoned plagioclase crystals that make up a significant percentage of the Bidkhan plagioclases and occur in all of the rock types, with a compositional range from 30 An mol% in core to 55 in rim; 3) Normal oscillatory zoned plagioclases that also occur in all of the rock types; their An mol% fluctuates from core to rim, The ∆An in oscillations are relatively small (~5 An mol% ), that suggest newly melts were nearly similar in composition; 4) Reverse oscillatory zoned plagioclases, in this group of plagioclase crystals, An mol % content fluctuates and increases from their core to rim overally. Investigation of chemistry data in Bidkhan reveals that there are some plagioclase crystals with calcic cores (An 75 mol %) in andesites. These features must be established due to magma mixing. This situation that has stated by Toothil (2007) means a combination of fractionation and magma mixing, where crystals growth in a relatively shallow magma chamber has periodically been interrupted by injection of other melts, with nearly similar composition of some many plagioclase phenocrysts. All these data suggest that,in Bidkhan, before and during eruption, some phenomena like fractional crystalization(F.C), assimilation and crystal fractionation(A.F.C), crustal contamination and magma mixing processes have a greate role to construction of Bidkhan's volcanic products. Key words: A.F.C, Bidkhan, crustal contamination, F.C, magma mixing.
    Geoitalia 2011. 01/2011;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Dehsheikh peridotite massif is located in the Esfandagheh region in southeastern Iran at the NE edge of the main Zagros thrust and is part of the Orzuieh coloured mélange belt. The Dehsheikh massif consists of relatively unaltered harzburgite, lherzolite, dunite and several chromite deposits that are cut by pyroxenitic dykes. These peridotites display numerous evidences of mantle metasomatism at various scales. Dunite dykes, bands and patches as well as pyroxenites and chromite deposits were formed during several metasomatic stages. Textural features such as the incongruent melting of orthopyroxenes and interstitial spinels, olivines and pyroxenes suggest that mantle metasomatism has affected the Dehsheikh massif. The effects of the metasomatism can be traced in mineral chemistry and chemical zoning of the spinels and orthopyroxenes, as well as the REE patterns of the Dehsheikh harzburgites. These features indicate that the Dehsheikh peridotites were depleted in incompatible elements, light REE, as a consequence of partial melting prior to being metasomatized by migrating melts at mantle conditions. Our observations also suggest that ascending melts in the deeper levels of the upper mantle began to react with depleted peridotites and produced incongruently melted orthopyroxenes, dunites and impregnated harzburgites. The composition of the melts gradually changed toward boninite due to melt–peridotite reaction. These processes produced the chromite deposits and their dunitic envelopes in the upper levels of the mantle. Following the early pervasive metasomatism, pyroxenitic melts invaded the peridotite at shallower depths. These events suggest that the Dehsheikh peridotites were formed in a supra-subduction zone setting.
    Ore Geology Reviews - ORE GEOL REV. 01/2011; 39(4):245-264.
  • A.R. Najafzadeh, M. Arvin, Y. Pan, H. Ahmadipour
    geoitalia; 01/2011
  • Source
    Shahram Khalili Mobarhan, Hamid Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: 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
    4th national Payame Noor geological conference; 11/2010
  • Source
    Shahram Khalili Mobarhan, Hamid Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: Mount Bidkhan stratovolcano has located in SE of Central Iranian Volcanic Belt. This volcano shows at least 5 eruption phases with two major andesitic and dacitic rock types. Pyroxenes are more abundant and clinopyroxenes are more than orthopyroxenes. Clinopyroxenes with compositional variations and prefect mineral zoning can be used for distinguishing the evolution of parental magmas during eruption. Clinopyroxenes are mainly diopside and augite types and orthopyroxenes have hypersthene composition. Because these pyroxenes can not crystallize from dacitic and andesitic magmas, so it is probably that Bidkhan parental magmas have been produced by mixing of various melts with different chemical compositions. Magma mixing can occur in crustal magma chambers and then, the hybrid magmas erupt at the surface. Keywords: Central Iranian Volcanic Belt, Clinopyroxene, Mixing, Orthopyroxene, Stratovolcano
    SCM 17th; 08/2010
  • Source
    Sh. Khalili Mobarhan, H. Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: 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 Bidkhan lavas. Chemical composition of pyroxenes along with different types of zoned plagioclase phenocrysts in Bidkhan and abnormal association of phenocrysts suggest that parental magmas in Bidkhan may have been produced by mixing of various melts with different chemical compositions. In addition, the integrated analysis of textural and chemical data allows establishing that magma mixing can occure in crustal magma chambers and the hybrid magmas erupt at the surface.
    IMA 2010; 01/2010
  • A.R. Najafzadeh, M. Arvin, Y. Pan, H. Ahmadipour
    6th International Dyke Conference, India.; 01/2010
  • A.R. Najafzadeh, M. Arvin, Y. Pan, H. Ahmadipour
    The 20th general meeting of the international mineralogical association, Budapest, Hungary.; 01/2010
  • Source
    Shahram khalili Mobarhan, Hamid Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: 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 melts. These two melts are then, mixed and resulted hybrid magmas, ascend toward the shallower reservoirs. Repeated magma injection gives rise to a second mixing event. Thus eruptive products at Mount Bidkhan have been originated from the mixing of intermediate hybrid magmas within shallow magma chambers. Sometimes, two melts have been erupted simultaneously as mingled melts. This model can be tested for other volcanic province of central Iranian volcanic belt.
    Journal of Sciences, Islamic Republic of Iran. 01/2010; 21(2)::137-153.
  • Source
    Shahram Khalili Mobarhan, Hamid Ahmadipour
    [Show abstract] [Hide abstract]
    ABSTRACT: Bidkhan stratovolcano has located in SE of Central Iranian Volcanic Belt, South of Bardsir, Kerman province. Eruptive products consist of pyroclastic surge, fall, flow and lava flow, dykes and plugs, brecciated lava and lahars with andesitic and dacitic composition. Parent magmas in Bidkhan produced from differentiation of high-k calcalkaline magma and after several eruptive events, their products have been deposited on Eocene volcanics. Keywords: Central Iranian Volcanic Belt – Stratovolcano - eruptive products - high Kcalcalkaline
    3d natonal Payame Noor university conference; 10/2009
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mount Bidkhan stratovolcano is located in the Central Iranian Volcanic Belt and contains Pliocene high-K calcalkaline andesitic and dacitic volcanics. The mineral assemblage is plagioclase, clinopyroxene, orthopyroxene, amphibole and biotite. Plagioclase is the most abundant phase in all of the rocks, and records textural and chemical variations, possibly revealing some stages of evolution for Mt. Bidkhan magmas. From field evidence, enclaves and banded rocks, different in their colour, indicate that mixing and mingling may have occured before eruption. In addition, features such as sieved and oscillatory zoned plagioclase, and the coexistence of several types of plagioclase phenocrysts within the same sample, are other indications of magma mixing and mingling processes. Based on textural and SEMEDS analyses, several types of plagioclases, different in their composition, have been found in these rocks, evidence of an effective role of mixing and hybridization. Types of plagioclase recognized are the following: 1) oscillatory zoned plagioclase (ΔAn of oscillations ∼5mol%) from core to rim; 2) normally zoned plagioclase (up to 75 An mol% at the core); 3) reversed zoned plagioclase (with 30 An mol% at the core and 50 An mol% at the rim); 4) oscillatory zoned plagioclase, with decreasing An mol% from core to rim; 5) reversed oscillatory zoned plagioclases, with increasing An mol% from core to rim. In addition to phenocrysts, rather homogeneous plagioclase microlites occur in the groundmass. The integrated analysis of textural and chemical data allows to establish that magma evolution was chiefly ruled by fractional crystallization processes at shallow depth, joined to repeated episodes of mixing due to inputs of less evolved magmas
    Goldschmidth 2009; 01/2009
  • A.R. Najafzadeh, M. Arvin, Y. Pan, H. Ahmadipour
    19th Goldschmidt conference, swiss.; 01/2009
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mount Bidkhan is an Oligo-Miocene stratovolcano, with a caldera, located in the southeastern part of the Central Iranian Volcanic Belt (CIVB). A detailed stratigraphically-controlled sampling of deposits was performed in the proximal, medial and distal sectors of the volcanic edifice. Eight kinds of products have been recognized: 1) pyroclastic flows 2) fall-out levels; 3) lahars; 4) surges 5) lava flows; 6) brecciated lavas and lava breccias; 7) dacitic domes/plugs; 8) ring and radial dykes. Major and trace element compositions of whole rocks were obtained on selected volcanics by means of WD-XRF and ICP-MS. Analyses on mineral phases were carried out by SEM-EDS; plagioclase and clinopyroxene were analyzed in detail along core-rim profiles and through X-ray mapping for major elements. Products exhibit high-K calcalkaline affinity and can be classified as andesites and dacites. The mineral assemblage is chiefly composed of plagioclase and, subordinately, clinopyroxene, orthopyroxene, amphibole, biotite and magnetite. Quartz phenocrysts and abundant Kfeldspar in the groundmass make the dacitic products peculiar. Accessory minerals are apatite, zircon and sphene. Core-rim compositional profiles in plagioclase and clinopyroxene evidence that almost all of the crystals are complexly zoned. Specifically, plagioclase and clinopyroxene commonly exhibit small-scale oscillatory zoning, which sometimes turns into significant An mol% and Mg# changes respectively. The integrated analysis of petrochemical data allows the preliminary hypothesis that the geochemical evolution of magmas might be chiefly ruled by AFC processes at shallow depth, to which repeated episodes of mixing due to inputs of less evolved magmas are superimposed. In particular, microanalytical data highlight that the most significant magma recharging episodes are recorded at the phenocryst rims, slightly prior to the eruption. Future research will be focused on possible relations between inputs of less differentiated magmas into the feeding system and the onset of violent strombolian to plinian eruptions.
    Goldschmidt Conference; 01/2008
  • A.R. Najafzadeh, M. Arvin, Y. Pan, H Ahmadipour
    Journal of Science, Islamic Republic of Iran. 01/2008; 19 (1):49-65.
  • Source