Economic Geology
Zafari Zafar Abad; Ebrahim Tale Fazel; Mehrdad Barati; Abbas Oroji
Abstract
The Yenganli gold deposit is one of the important indices of the Takab orefeild is located in the southern Zarshuran deposit and 42 km north of Takab Province. Based on structural subdivision of Iran, this deposit is situated between the Sanandaj-Sirjan zone and Uremia-Dokhtar magmatic arc and is related ...
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The Yenganli gold deposit is one of the important indices of the Takab orefeild is located in the southern Zarshuran deposit and 42 km north of Takab Province. Based on structural subdivision of Iran, this deposit is situated between the Sanandaj-Sirjan zone and Uremia-Dokhtar magmatic arc and is related to sedimentary-hydrothermal activities of the Takab orefield. The Yeganli deposit in the western part of the NW-SE-trending Iman Khan anticline and is similar to the Zarshuran deposit is composed of three Neoproterozoic lithostratigraphic unites, including, schist and serpentinite (Iman-Khan unit), limestone and dolomite (Chaldagh unit) and black shale and siltstone (Zarshuran unit). Mineralization occurs as vein-type, disseminated and breccia with a NNE-trending and 5 km2 thickness in the Zarshuran shale and siltestone and Chaldagh limestone host rocks.
A Zahedi1; M Boomeri; M.A Mackizadeh
Abstract
The garnets from the KhutSkarn in the west of Yazd have been formed as a result of hydrothermal activity ofOligo-Miocene calc-alkaline plutons. The chemical composition of garnets in the Khutskarn are divided into two solid solution of grossularitic-andraditic and almost pure andradite different types. ...
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The garnets from the KhutSkarn in the west of Yazd have been formed as a result of hydrothermal activity ofOligo-Miocene calc-alkaline plutons. The chemical composition of garnets in the Khutskarn are divided into two solid solution of grossularitic-andraditic and almost pure andradite different types. The Fe-rich garnets are isotropic (Adr>96), whereasgrossularitic-andraditic garnets are anisotropic and show compositional zoning and sectorial twinning(Ad74.3Gr24.8-Ad32.1Gr66.6). The compositional zoning of anisotropic garnets may result from hydrothermal overgrowths on contact metamorphic minerals, variations in P, T, XCO2, concentrations of Fe3+ and Al, or kinetic factors. The Laser Ablation ICP-MS results show isotropic garnets exhibit LREE-enriched and HREE-depleted patterns, with a positive Eu anomaly. These garnets grow rapidly under relatively high W/R ratios from the magmatic-derived fluids during infiltration metasomatism process, whereas anisotropic garnets have much lower enrichment in LREE and show a weak negative Eu anomaly. These garnets formed by prolonged interaction of pore fluids with the host rocks during the diffusive metasomatism process.
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.
