Petrology
zahra badrzadeh
Abstract
Abstract The studied Chaltian granitoid is located in the endpoint of the southern Sanandaj–Sirjan Zone. This pluton has Low-Al trondhjemitic composition with tholeiitic to transitional nature. The intrusion has been intruded in the early Mesozoic volcanic and sedimentary rocks. According to U-Pb ...
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Abstract The studied Chaltian granitoid is located in the endpoint of the southern Sanandaj–Sirjan Zone. This pluton has Low-Al trondhjemitic composition with tholeiitic to transitional nature. The intrusion has been intruded in the early Mesozoic volcanic and sedimentary rocks. According to U-Pb SHRIMP age dating of zircon grains, this pluton was intruded at the 187.5 ±3.2Ma ago. Studied pluton has low Al2O3, Sr/Y, (La/Yb)N ratio and less fractionated REE pattern. In the primitive mantle normalized spider diagrams, studied samples show enrichment of LIL elements such as K, Rb, Ba and Th relative to HFS elements and has negative anomaly in Ta, Nb and Ti elements, which are considered characteristic of magmas generated in subduction related settings. In terms of their origin, based on geological and geochemical characteristics, trondhjemitic melt has been generated by low pressure dehydration melting of amphibolitic source in an continental extensional tectonic setting related to subduction environment.
M Aghazadeh; Z Badrzadeh; A Castro
Abstract
The studied Roudbar and Abhar plutons are located in the western Alborz zone and Taroum subzone. These intrusive bodies show metaluminous and shoshonitic nature and they cut the Eocene volcanic and sedimentary rocks. In the studied plutons, monzonite and quartz monzonite terms are dominant. According ...
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The studied Roudbar and Abhar plutons are located in the western Alborz zone and Taroum subzone. These intrusive bodies show metaluminous and shoshonitic nature and they cut the Eocene volcanic and sedimentary rocks. In the studied plutons, monzonite and quartz monzonite terms are dominant. According to geochemistry, these plutons were crystallized from non-primary magma, and have been experienced fractional crystallization. In the primary mantle normalized spider diagrams and chondrite normalized REE diagrams, studied samples show clear enrichment in the LREE and LILE and depletion in the HFSE. The primary magma originated from 1-5% partial melting of phlogopite bearing lithospheric mantle with spinel lherzolite composition that metasomatized by subduction agents. According to U-Pb SHRIMP dating, these plutons were intruded during 37.8 to 38.9 Ma in the late Eocene and in a post-collision tectonic setting.
M Aghazadeh; Z Badrzadeh
Abstract
In the northwestern Iran mica-and amphibole-rich lamprophyres crop out mainly as dyke and they cut Pre-Pliocene strata. They exposed in the Arasbaran, EslamyPeninsula, and Mishu range. According to the mineralogy and mineral chemistry, amphibole-rich lamprophyres have kaersutite type amphiboles and diopside ...
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In the northwestern Iran mica-and amphibole-rich lamprophyres crop out mainly as dyke and they cut Pre-Pliocene strata. They exposed in the Arasbaran, EslamyPeninsula, and Mishu range. According to the mineralogy and mineral chemistry, amphibole-rich lamprophyres have kaersutite type amphiboles and diopside phenocrysts in the matrix of same mafic minerals, feldspars, and altered glass. These lamprophyres in some thin sections have olivine and phlogopite. Mica-rich lamprophyres include phlogopite and diopside phenocrysts in the matrix of same mafic minerals, abundant glass and secondary minerals. According to the mineralogy, mineral chemistry, and geochemistry, amphibole-rich lamprophyres are alkaline and show camptonite-sannaite composition but mica-rich lamrophyres are calc-alkaline and represent minette composition. Alkaline lamprophyres represent characteristics of OIB type magma while calc-alkaline lamprophyres show characteristics of magmas originated in the subduction dominant tectonic setting. Sorkheh amphibole-bearing lamprophyres show both alkaline and calc-alkaline type lamprophyres. Regarding to geochemical features both calc-alkaline and alkaline lamprophyres originated from heterogeneous mantle with different proportions of spinel, garnet and hydrous minerals (e.g. phlogopite and amphibole). Calc-alkaline lamprophyres originated from a mantle enriched in phlogopite and alkaline lamprophyres originated from lithospheric mantle that metasomatised by deep mantle and enriched in amphibole. Both mentioned mantles associated in the petrogenesis of the Sorkheh amphibole- bearing lamprophyres. The lamprophyres were emplaced in the post collisional tectonic setting.
zahra badrzadeh; M. Sabzehei; E. Rastad; M. H. Emami; D. Gimeno
Abstract
The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons ...
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The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons in distal part of the deposit, the occurrence of a stringer zone discordantly under massive ore, the presence of pyrite as the main sulfide mineral, brecciated textures and mineralogical zonation in the massive ore, all suggest that the Sargaz deposit can be classified as a volanogenic massive sulfide deposit. The mineralogy is reasonably simple, with pyrite being the main sulfide mineral, with lesser chalcopyrite and sphalerite. On the basis of different generation of minerals, shape, size, their mutual geometry, relative timing of crosscutting structures and replacement features, brecciated textures and mineralogical zonation indicate that the growth history of the Sargaz deposit was complex due to syn and post depositional processes. Based on mineralogical, textural and paragenetic relationships, four principal stages of mineralization are recognized. Stage I mainly consist of fine grained pyrite (As rich), and locally sphalerite, quartz and barite. Framboidal pyrite, colloform pyrite and sphalerite were formed during this stage. After stage 1 mineralization, collapse of the sulfide mounds took place probably due to dissolution of anhydrite matrix, producing accumulations of pyrite breccias. Following this mound collapse, during stage II, pyrite (Co rich), sphalerite, tetrahedrite-tenantite and galena were formed as euhedral and coarse grains. Stage III deposits consist of chalcopyrite replacements and zone refining process. During this stage, due to zone refining, a chalcopyrite-pyrite zone was developed at the lower part of the massive sulfide lens and a sphalerite-rich zone formed in the upper part. During stage IV, over refining process, led to the dissolution of stage III chalcopyrite and base-metal depleted pyrite body in the lowermost part of the massive sulfide lens and carbonate veins were emplaced into the sulfide lens replacing earlier barite.
