Economic Geology
Robabeh Masoomi; Yousef Rahimsouri; Hemayat Jamali; Ali Abedini
Abstract
The aim of this research is the geochemical study of the major and trace elements of the alteration systems in the Kamar-Gov district (south of Hashtjin, Ardabil province). The rock units of the studied area include volcanic rocks with the composition of basaltic-trachy andesite to rhyolite and ...
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The aim of this research is the geochemical study of the major and trace elements of the alteration systems in the Kamar-Gov district (south of Hashtjin, Ardabil province). The rock units of the studied area include volcanic rocks with the composition of basaltic-trachy andesite to rhyolite and crystal vitric-tuff with Eocene and Oligocene age. These rocks have calk alkaline and shoshonitic affinity and belong to post-collisional arc tectonic setting. In the Kamar-Gov district, the alteration zones include silicic, sericitic (quartz + muscovite + pyrite ± illite ± rutile), sericite-argillic (quartz + sericite + kaolinite + dolomite), intermediate argillic (quartz + kaolinite + illite), advanced argillic (quartz + kaolinite + alunite + diaspore ± anatase ± muscovite), and chloritic (quartz + chlorite + illite). The distribution pattern of the normalized-BSE major and trace elements and the mass change calculations (volume factor method) show that the silicic and advanced argillic alteration zones have more elemental depletion and different distribution patterns from the parent rock. However, chloritic, intermediate argillic, and sericite-argillic alterations have relatively little mass change and almost similar distribution patterns to the primary parent rock. The major elements like Ca, Mg, Al, Na, and Fe have frequently depleted. Ti shows slight depletion. K has frequently enriched. Trace elements such as Zr, Nb, Sc, and Th have mass reduction. Co, Cr, Ni, and Rb have experienced depletion and enrichment processes. Sr and V show relatively high depletion. Sb, S, and As (chiefly) have enriched. LREEs have depleted more than HREEs. Elements like Pb, Zn, and Cu only in the siliceous and sericite-argillic zone show enrichment. This research shows that factors like pH of hydrothermal fluid and primary rock-forming and secondary minerals resulting from alteration have caused differences in the behavior and concentration of elements in different alteration zones in the Kamar-Gov district.
Economic Geology
Robabe masoomi; Yoseph Rahimsouri; Hemayat Jamali; Ali Abedini
Abstract
The action of alteration processes on the Eocene tuffs has led to the formation of a spread argillic alteration zone in the Kamar district (south of Ardebil, Tarom-Hashtjin Zone). The aim of this study is to determine the factors controlling argillic alteration, using mineralogical studies and chemical ...
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The action of alteration processes on the Eocene tuffs has led to the formation of a spread argillic alteration zone in the Kamar district (south of Ardebil, Tarom-Hashtjin Zone). The aim of this study is to determine the factors controlling argillic alteration, using mineralogical studies and chemical alteration indices. Quartz, kaolinite, muscovite (sericite), rutile, anatase, illite, diaspore, alunite, albite, clinochlore, jarosite, gypsum, pyrite, orthoclase and dolomite are the mineral assemblage of this alteration zone. The mineralization of sulfides includes pyrite (predominantly), chalcopyrite, borneite, chalcocite, galena, and sphalerite. The chemical index of alteration (CIA) values are between 51.55 to 74.3 %, and the mineralogical index of alteration (MI) values vary from 8.22 to 48.3%. The mafic index of alteration (MIA(O)) ranges from 55.88% to 87.48%, Depletion of a large number of elements, including some immobile elements (Zr, Y, V, Al and LREEs), the presence of minerals indicating acidic pH, such as jarosite and alunite, and high-temperature minerals such as rutile and anatase, the presence of the vuggy quartz in some altered regions, and concomitant enrichment of As, Sb and Mo, in the Kamar argillic zone, bear similarities to the hot fluid alterations of high-sulfidation epithermal deposits.
Sh Fatahi; A.A Calagari; A Abedini; H Bagheri
Abstract
Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies ...
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Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies testified to the presence of minerals such as montmorillonite, saponite, beidellite, cristobalite, anorthite, calcite, dolomite, albite, vermiculite, actinolite, pyrophyllite, quartz, sanidine nontronite, orthoclase, microcline, tridymite, and hematite in rock-forming quantities in the bentonitic samples. Based on the minerals chemistry considerations, the Chahreeseh bentonite deposit can be classified as the Wyoming type. The results of mass change calculations (with assumption of Hf as low-mobile index element) show that progression of bentonitization process at Chahreeseh was accompanied by depletion of elements like Al, Fe, K, Ti, Mn, P, Ba, Co, Zn, Cs, Rb, Y, Zr, Ni, Sr, and Cu, enrichment of U, and leaching-fixation of elements such as Na, Mg, Ca, and Si. The geochemical interpretations revealed that variations of Eu negative anomaly (0.27-0.90) and weak negative to weak positive anomalies of Ce (0.97-1.22) at Chahreeseh have been controlled by the degree of feldspar alteration and changes in the rate of oxidation potential of the environment, respectively. By considering the results obtained from field relations, mineralogy and geochemistry, it seems factors such as physico-chemical conditions of alteration environment, absorption mechanism, difference in degree of alteration intensity of parent materials, the degree of access to fluoride, chloride, and sulfate ligands, incorporation in crystal structure, ionic exchange, physical concentration, and the presence in resistant mineral phases played significant roles in distribution and concentration of elements in this deposit, respectively.
A. Abedini; A. A. Calagari
Abstract
Depositional cessations during Permian period in north of Saqqez were associated with development of lenses of bauxite-kaolin ores in Ruteh carbonate formation. In one of these lenses considered, six lithologic units were recognized which are from bottom to the top, (1) dark brown red, (2) violet, (3) ...
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Depositional cessations during Permian period in north of Saqqez were associated with development of lenses of bauxite-kaolin ores in Ruteh carbonate formation. In one of these lenses considered, six lithologic units were recognized which are from bottom to the top, (1) dark brown red, (2) violet, (3) multicolor, (4) pink (5) yellow, and (6) white (kaolin). Calculations of absolute weathering index for these units indicate that elements such as Si, Na, K, P, Mn, Mg, Ca, Sr, Ba, and Lu were leached during the weathering processes from basaltic rocks and elements such as Th, U, Y, Nb, Hf, Zr, Tb, Dy, Ho, Er, Tm, and Yb enriched. Whereas, elements such as Al, Fe, Ti, Rb, V, Cr, Ni, Co, La, Ce, Pr, Nd, Sm, Eu, and Gd have born leaching-fixation processes during the development of the weathered profile. The obtained results show that processes such as adsorption, scavenging and concentration by Fe-oxides and hydroxides, stability of metal-carrying complexes, variations in chemistry of weathering solutions, the presence of organic matters, fixation in neomorph phases, and the presence in the resistant mineral phases were the important factors that have played pronounced roles in distribution of elements in these deposits.
A. Zarasvandi; H. Zamanian; E. Hejazi; A.H. Mansour
Abstract
The Sar-Faryab bauxite deposit is located in 250 km east of Ahvaz city in Kohgeloye and Bovair-Ahmad Province, Iran. Structurally the deposit is located in the Zagros Simply Fold Mountain Belt and was formed between the Ilam and Sarvak Formations. The bauxite horizon in this deposit consists of ...
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The Sar-Faryab bauxite deposit is located in 250 km east of Ahvaz city in Kohgeloye and Bovair-Ahmad Province, Iran. Structurally the deposit is located in the Zagros Simply Fold Mountain Belt and was formed between the Ilam and Sarvak Formations. The bauxite horizon in this deposit consists of marly limestone, argillite, oolitic-Pisolitic, yellow, red and white bauxite. This study uses the geochemistry of immobile elements (Al, Ti, Zr and Y) to trace the precursor rock of the bauxite deposit and to calculate the mass changes that took place during weathering and bauxitization. The result indicates that elements are depleted and elements are enriched during the weathering and bauxitization. Geochemical data show that argillaceous debris in the Sarvak limestone can be the source of the Sar-Faryab bauxite deposit.
D. Esmaeily; S. Z. Afshooni
Abstract
The Astaneh granitoid massif in the Sanandaj-Sirjan zone, covering an area of about 30 km2, located in 40 km to Arak city, is mainly composed of granodioritic rocks. They are widely affected by hydrothermal alteration and six alteration zones including phyllic (sericitic), chloritic, propylitic, argillic, ...
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The Astaneh granitoid massif in the Sanandaj-Sirjan zone, covering an area of about 30 km2, located in 40 km to Arak city, is mainly composed of granodioritic rocks. They are widely affected by hydrothermal alteration and six alteration zones including phyllic (sericitic), chloritic, propylitic, argillic, albitic and tourmalinization zones are identified in this area. Calculations of chemical index of alteration (CIA) indicates that phyllic (sericitic), chloritic, propylitic, argillic, albitic and tourmalinization alteration zones underwent the hydrothermal alteration about 63.47%, 59.73%, 61.54%, 63.69%, 60.61%, 65.43% respectively. The mass changes of elements, based on Al (as a monitor immobile element), indicate that considerable amounts of oxides such as Fe2O3, MgO, CaO and TiO2 and also LFSEs such as K, Rb, Sr, Cs and Ba in all of the alteration zones were depleted. The results show that SiO2 was added to the phyllic (sericitic), argillic and tourmalinization alteration zones by metasomatizing fluids. Al2O3 was immobile and its mass was essentially unchanged during alteration. Other oxides such as MnO, Na2O, K2O and P2O5 and also LOI show dissimilar behaviors in the different zones. In all of the zones there is depletion in Sc and Y (HFSE). Also the Ga (except in chloritic zone) and U (except in phyllic zone) were depleted. In the phyllic zone, La, Ce, Pr, Nd (LREE), Sm, Eu, Gd (MREE) and Yb (HREE) were added; however, Dy, Er and Ho were depleted, whereas Tb and Lu were unchanged. In all zones the REEs were depleted except in the chloritic zone where Eu and Yb were added and Lu was essentially unchanged during alteration.