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.
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
A Permian residual horizon is located in ~30 km northeast of Malekan, which was developed as stratiform layer in Ruteh carbonate rocks. Mineralogically, this horizon includes minerals such as boehmite, diaspore, hematite, kaolinite, rutile, anatase, montmorillonite, muscovite, calcite, and chlorite. ...
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A Permian residual horizon is located in ~30 km northeast of Malekan, which was developed as stratiform layer in Ruteh carbonate rocks. Mineralogically, this horizon includes minerals such as boehmite, diaspore, hematite, kaolinite, rutile, anatase, montmorillonite, muscovite, calcite, and chlorite. Calculations of normative values of minerals in a selective profile show that this horizon consists of five distinct lithological facies which are, from bottom to the top, (1) kaolinitic ferrite, (2) ferritic kaolin, (3) ferritic bauxite, (4) kaolin, and (5) bauxitic kaolin. Based on obtained data, it seems that the distribution of REEs in the studied profile was principally controlled by factors such as (1) Eh variations of the environment due to decomposition of organic matters, (2) the pH increase of weathering solutions by carbonate bedrocks, (3) scavenging and fixation processes, and (4) fluctuation of underground water table. Further geochemical evidence indicates that the concentration of LREEs were occurred by muscovite, Mn-oxides, and secondary phosphates (e.g., monazite, gorceixite, rhabdophane) and that of HREEs by rutile, anatase, and zircon in the studied profile.
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.
