F Kangarani Farahani; A.A Calagari; A Abedini
Abstract
Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, ...
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Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, colloformic, pseudo-porphyritic, and nodular textures within the ores of this deposit. Mineralogical data show that the ores contain diaspore, goethite, anatase, kaolinite, hematite, boehmite, and zircon. Considering the mineralogical composition and textural characteristics, this deposit was formed in an almost reduced near-surface environment. Geochemical indices like Eu/Eu* along with ratios such as Ti/Zr, Nb/Y, and Al/Ti suggest that Kambelu deposit is a product of alteration and weathering of rocks of trachy-andesitic to basaltic composition. Comparison of the variation trend of elements like Si, Al, and Fe within a selective profile reveals that the variation in chemistry (i.e., pH) of solutions responsible for lateritization and drainage intensity are the two principal factors for formation of the ores. Geochemical considerations show that distribution of trace elements in this deposit is a function of factors such as adsorption, scavenging by metallic oxides and hydroxides, fixation in neomorphic phases, and presence in resistant mineral phases. Inharmonic distribution of REEs in the studied profile indicates an allogenic origin for this deposit. The obtained data indicate that clays, anatase, zircon, xenotime, gorceixite, and churchite are the potential hosts for REEs in this deposit.
F Kangarani Farahani; A.A Calagari; A Abedini
Abstract
The Shahbolaghi laterite deposit is located in ~40 km southeast of Damavand, Tehran province. This deposit was developed as stratiform horizons within the shales and sandstones of Shemshak formation (Jurassic). Mineralogical investigations show that the major minerals in this deposit include hematite, ...
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The Shahbolaghi laterite deposit is located in ~40 km southeast of Damavand, Tehran province. This deposit was developed as stratiform horizons within the shales and sandstones of Shemshak formation (Jurassic). Mineralogical investigations show that the major minerals in this deposit include hematite, boehmite, and anatase accompanied by lesser amounts of goethite, magnetite, chamosite, kaolinite, quartz, calcite, diaspore, zircon, pyrite, and rutile. The microscopic evidences such as development of spastoidic textures within the ores suggest a high energy water-saturated sedimentary environment during the lateritization processes. By considering the mineral assemblage and textural characteristics, deposition and diagenesis of this horizon occurred in an oxidizing and almost near surface environment. Based on the obtained data from the field observations, geochemistry of major, trace, and rare earth elements the lateritic horizon at Shahbolaghiwas developed probably byalteration of parent rocks with basaltic composition. The bauxitization process was occurredintrends of kaolinization, destruction of kaolinite, and deferrugenization. The geochemical investigations indicated that the distribution of trace elements in this horizon was controlled by clays and minor mineral phases.
