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.
Economic Geology
masoumeh Norouzi; Ali Abedini; Ali Asghar Calagari; Fatemeh Kangarani Farahani
Abstract
The kaolin occurrence in the Abolhasani-Zereshkouh area (south of Shahroud, northeast of Iran) is a product of alteration of Eocene andesitic rocks. With attention to mineralogical studies, kaolinite, quartz, chlorite, montmorillonite, illite, rutile, calcite, orthoclase, albite, vermiculite, palygorskite, ...
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The kaolin occurrence in the Abolhasani-Zereshkouh area (south of Shahroud, northeast of Iran) is a product of alteration of Eocene andesitic rocks. With attention to mineralogical studies, kaolinite, quartz, chlorite, montmorillonite, illite, rutile, calcite, orthoclase, albite, vermiculite, palygorskite, jarosite, and hematite are the mineral assemblege of this alteration occurrence. Calculations of mass balance of elements with assuming Zr as monitor immobile element show that elements such as Si, Fe, Mg, Na, K, Ti, Cr, Ba, Be, Co, Cs, Rb, Sn, U, V, W, Ni and REE were partially depleted and elements such as Hf, Zn and Cd enriched during the kaolinitization processes of andesitic rocks. Other elements including Al, Ca, P, Mn, Ga, Nb, Sr, Ta, Th, Y, Cu, Pb and Tl were undergone both leaching and fixation processes. The mass decrease of Si, Fe, K, Rb, Cs and Ba reveals destruction of plagioclase and hornblende by highly acidic hydrothermal fluids. The presence of two abnormal decreasing and increasing trends for the elements Al, Ga, P, Nb, Ta, and Y can be attributed to the low pH of the altering fluids, the high water-to-rock ratio and the abundance of complexing legands.
Economic Geology
nasrin khajehmohammadlou; Ali Asghar Calagari; Kamal Siahcheshm; Ali Abedini
Abstract
The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, ...
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The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, and marble in the study area. The garnets of the Aghbolagh skarn belong to solid solution series of grossularite-andradite in which andradite is the dominant phase (>80%). These garnets are isotropic and lack zonation. The pattern of REE distribution in these garnets shows the enrichment of LREE relative to HREE and also the occurrence of negative anomalies of Eu/Eu* and Ce/Ce*. The comparison of the distribution pattern of REE in garnets with those in igneous (granite and monzonite) and sedimentary (carbonates and sandstones) rocks demonstrates that the REE in garnets were derived mainly from the igneous rocks rather than the sedimentary units. The increase in Pr/Yb ratios in parallel with increase in the ƩREE is indicative of the magmatic origin of the ore-forming fluids in the Aghbolagh skarn. However, the lack of sensible variations between Ce/CE* and ƩREE values indicate that the meteoric waters might have also played a part in skarn-forming fluids at Aghbolagh.
Economic Geology
Maryam Kiaeshkevarian; Ali Asghar Calagari; Ali Abedini; GholamHossein Shamanian
Abstract
The Gheshlagh bauxitic deposit is located in ~110 km southeast of Gorgan city. Mineralogical studies indicated the presence of minerals such as boehmite, diaspore, kaolinite, hematite, goethite, anatase, rutile, chamosite, calcite, moscovite, clinoclar, provskite, quartz, and dolomite. Based on quantitative ...
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The Gheshlagh bauxitic deposit is located in ~110 km southeast of Gorgan city. Mineralogical studies indicated the presence of minerals such as boehmite, diaspore, kaolinite, hematite, goethite, anatase, rutile, chamosite, calcite, moscovite, clinoclar, provskite, quartz, and dolomite. Based on quantitative mineralogy this deposite made up of (1) bauxitic clay, (2) clayey bauxite, (3) bauxitic clayey iron ore and (4) bauxitic iron ore. Calculations of the enrichment factors, with assumption of upper continental crust (UCC) as parent rocks, showed that elements such as Rb, Cs and Ba were depleted during bauxitization processes whereas elements like Y, Cr, Co, Ni, V and HREEs were encountered enrichment.Elements like Sr, Ga, Zr, Hf, Nb, Ta, U, Th and LREEs underwent both leaching and fixation processes during development of the weathered profile. Combination of the results obtained from mineralogical and geochemical investigations showed that factors such as adsorption, scavenging by metallic oxides and hydroxides, fluctuation of underground water level, type and stability of metal-containing complexes, stability of primary bearing minerals, presence in mineral phases resistant to weathering and changes in chemistry of the solutions responsible for weathering played prominent role in distribution and mobilization of elements in the studied bauxitic ores.
Economic Geology
Majid Hafez Darbani; Ali Abedini; Farhang Aliyari; Ali Asghar Calagari
Abstract
The Kuh-Baba iron ore deposit is located in ~70 km south of Hashtroud, East-Azarbaidjan province, NW Iran. The lithologic units cropped out around this deposit include Oligo-Miocene volcanic-sedimentary rocks, Pliocene intrusive rocks, and Pliocene dacitic domes. The principal host rocks for the Fe mineralization ...
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The Kuh-Baba iron ore deposit is located in ~70 km south of Hashtroud, East-Azarbaidjan province, NW Iran. The lithologic units cropped out around this deposit include Oligo-Miocene volcanic-sedimentary rocks, Pliocene intrusive rocks, and Pliocene dacitic domes. The principal host rocks for the Fe mineralization include units of gabbro-norite, pyroxene hornblende gabbro-norite, and monzo-diorite. Remote sensing investigations (using Sentinel satellite images) display the presence of lineaments, NE-SW trending fault structures, and various alteration zones. The dominant hydrothermal alteration in inner parts of the deposit is mainly propylitic (epidote, chlorite, sericite) which gradually changes to argillic outward toward the peripheral parts. Based upon field relations and microscopic examinations, the ores show massive, vein/veinlet, brecciated, and disseminated textures. In the propylitic zone, magnetite is accompanied by epidote and actinolite. The geochemical studies revealed that the FeT content in the diamond drill core samples varies from 3.85 wt% to 63.2 wt%. Ground magnetic survey was conducted in the area and also, the maps of total magnetic field, reduced to pole magnetic, analytic signal, first vertical derivative, and upward continuation were prepared in an attempt to identify the potential deep and shallow subsurface mineralized zones. The obtained results show that two anomalies, one in the north and the other in the central parts of the study area, were recognized which almost correspond with the location of the intrusive bodies.
A. Abedini
Abstract
Intrusion of quartz-monzodioritic igneous bodies of Oligocene age into the Eocene lithic crystal tuffs and trachy-basalts resulted in occurrence of widespread argillic alteration zone in the Jizvan area (Tarom-Hashtjin zone). Mineralogical studies indicate that this alteration zone includes kaolinite, ...
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Intrusion of quartz-monzodioritic igneous bodies of Oligocene age into the Eocene lithic crystal tuffs and trachy-basalts resulted in occurrence of widespread argillic alteration zone in the Jizvan area (Tarom-Hashtjin zone). Mineralogical studies indicate that this alteration zone includes kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, rutile, calcite, feldspar, chlorite, hematite and goethite minerals. Hypogene ore minerals within the silicic-carbonatic veins and veinlets of argillic alteration zone contain chalcopyrite, galena and pyrite accompanied by goethite, malachite and azurite of supergene origin. Mass changes calculations of elements with assumption of Al as a monitor immobile element indicate that elements such as Ti, P, Th, Nb, Ta, Y and Zr have suffered leaching during argillization of lithic crystal tuffs. This abnormal behaviour is in relation to low pH of altering solutions, high water/rock ratio, abundance of complexing ions and suitable drainage system. The distribution pattern of REEs normalized to chondrite shows differentiation and enrichment of LREEs relative to HREEs and occurrence of negative Eu and Ce anomalies during argillization of lithic crystal tuffs. Geochemical investigations reveal that occurrence of negative Ce anomaly (0.49-0.92) is in relation to the destruction of zircon by acidic-oxidizing fluids. Negative Eu anomaly (0.23-0.73) and mass loss of elements such as Si, Fe, K, Rb, Cs, Sr and Ba indicate destruction of plagioclase and hornblende by strongly acidic hydrothermal fluids and high oxygen fugacity of environment. The correlation coefficients between elements display the controlling role of Mn-oxides in distribution and concentration of REEs, Pb, Zn and Cu. Mineralogical and geochemical evidence such as presence of pyrophyllite, alunite and rutile, enrichment of LREEs relative to HREEs, low values of La+Ce+Y, negative Ce anomaly and strong positive correlations between (LREEs/HREEs)N-LOI and (La/Lu)N-P suggest that the development and evolution of argillic alteration zone in the Jizvan area is affiliated to hypogene processes.
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. Abedini; A. A. Calagari
Abstract
Karstic bauxite horizon at Kanisheeteh is located ~19km east of Bukan, south of West-Azarbaidjan province, NW of Iran. This horizon lies conformably along the boundary of Ruteh (carbonate-shale) formation (middle to upper Permian) and Elika (carbonate) formation (lower Triassic), and consists of five ...
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Karstic bauxite horizon at Kanisheeteh is located ~19km east of Bukan, south of West-Azarbaidjan province, NW of Iran. This horizon lies conformably along the boundary of Ruteh (carbonate-shale) formation (middle to upper Permian) and Elika (carbonate) formation (lower Triassic), and consists of five distinct lithic units. Field evidence, petrographical and mineralogical examinations showed that fluctuations of climatic conditions along with structural stresses had a great influence in the formation of this horizon. Distribution pattern of REE (normalized to chondrite) indicates an intensive fractionation and enrichment of LREE over HREE, and an authigenic formation for the horizon. Calculations of absolute weathering index (AWI) and assumption of Nb as an immobile element and the upper continental crust (UCC) as a source for parent materials show that leaching and fixation processes are the two major regulators in concentrating of trace-elements in this horizon. Geochemical investigations indicate that distribution of Al, Fe, Si had great influence in changes of La/Y ratio, distribution of trace-elements in residual system, and Eu anomaly. Incorporation of the obtained results revealed that textural variations, preferential adsorption by metallic oxides (hematite), buffering of weathering solutions by carbonate bedrock, mineralogical control, and pH changes of the environment are the most important controlling factors in the distribution of LREE, HREE, HFSE, LILE and TTE during lateritization processes at Kanisheeteh.