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    • List of Articles محمد هاشم امامی

      • Open Access Article

        1 - Eocene-Oligocene volcanic units of momen abad, east of Iran: petrogenesis and magmatic evolution
        Sahar Tarabi Mohamad Hashem Emami Sourosh Modabberi Seyed Jamal Sheikh Zakariaee
        This study investigates petrology and major, minor, and rare earth elements ‎geochemistry of ‎East Iranian Eocene–Oligocene volcanic rocks in Sistan suture ‎zone, to examine their ‎petrogenesis and magma evolution. The volcanic rocks include andesi More
        This study investigates petrology and major, minor, and rare earth elements ‎geochemistry of ‎East Iranian Eocene–Oligocene volcanic rocks in Sistan suture ‎zone, to examine their ‎petrogenesis and magma evolution. The volcanic rocks include andesite, trachy-andesite, dacite ‎and rhyolite. ‎These calc-alkaline rocks of high-K series are enriched in Large ‎Ion Lithophile ‎Elements of Rb and Ba and depleted in High Field Strength Elements ‎(e.g. Ti and Nb). The REE ‎pattern shows Eu negative anomaly. These ‎features are comparable with rocks in subduction ‎zone of continental ‎margin setting. ‎The petrographic features and the geochemical variation ‎of major oxides and trace ‎elements against SiO2 can be related to fractional ‎crystallization in parent magma. The trace ‎element ratios, e.g. Nb/La, Nb/U, Ba/Rb, Nb/Y and Rb/Y, verify crustal ‎contamination with a remarkable upper ‎crustal contamination as the main ‎process in the ‎formation of volcanic series. ‎The ratios of Nb/Ba and Nb/Zr indicate that magmatic activity in Momen Abad had ‎resulted ‎from sub-continental lithospheric mantle. In addition, Nb/Y and Zr/Yb versus ‎Ta/Yb reveals an ‎E-MORB like mantle source. A spinel lherzolite composition ‎with significant role of the ‎AFC processes are deduced from the concentrations of Yb and ‎Y, and the ratios of Th/Yb and ‎La/Yb. ‎The Ba/Nb, Ba/Th and Th/Nb ratios presume a metasomatized mantle source ‎resulted from ‎the melting of upper crust sediments inherited from the subduction of ‎Neotethys ocean beneath ‎the Lut Block. ‎ Manuscript profile
      • Open Access Article

        2 - Magmatic interactions as recorded in plagioclase phenocrysts of quaternary volcanics in SE Bam (SE Iran)
        Abdollah Yazdi Afshin Ashja Ardalan Mohammad Hashem Emami Rahim Dabiri Mohammad Foudazi
        In the southeast of Iran (SE Bam), there is a collection of volcanic rocks with andesite, basalt and trachyandesite composition. The textures of these rocks are often porphyritic with microlithic, porphyric cavity, and sometimes glomeroporphyritic, sore throat trachytic More
        In the southeast of Iran (SE Bam), there is a collection of volcanic rocks with andesite, basalt and trachyandesite composition. The textures of these rocks are often porphyritic with microlithic, porphyric cavity, and sometimes glomeroporphyritic, sore throat trachytic. Main minerals include olivine, clinopyroxene, plagioclase and secondary minerals including opaque minerals, Iddingsite, secondary biotite, chlorite and calcite. The analysis of magma textures gives us valuable information about magmatic processes. Micro textures in plagioclase of volcanic rocks in the region are divided into two groups: a) texture-linked to crystalline growth including: sieve texture, oscillatory zoning and degraded surfaces and b) Morphological textures such as glomerular crystals. Sieve texture and zoning in crystal represent processes such as magmatic mixing and abrupt reduction of pressure and, in general, unbalanced conditions in magmatic reservoirs. Based on electron microscope studies, plagioclase of igneous rocks of the region is within the boundaries of labradorite and bytownite.In the southeast of bam, there is a collection of volcanic rocks with andesite, basalt and trachy andesite composition. The texture of these rocks are often porphyritic with microlithic, porphyric cavity, and sometimes glomerulophorphuri, sore throat trachytic. Main minerals include Olivine, Clinopyroxene, Plagioclase and secondary minerals including opaque minerals, Iodenzyte, secondary Biotite, Chlorite and Calcite. Sieve texture and zoning in crystal represent processes such as magmatic mixing and abrupt reduction of pressure and, in general, unbalanced conditions in magmatic reservoirs. Manuscript profile