Acta Geodynamica et Geomaterialia

Title: GEOCHEMICAL CHARACTERISTICS OF LATERITE: THE JURASSIC ZAN DEPOSIT, IRAN
Authors: Calagari Ali Asghar, Farahani Fatemeh Kangarani and Ali Abedini
DOI: 10.13168/AGG.2015.0001
Journal: Acta Geodynamica et Geomaterialia, Vol. 12, No. 1 (177), Prague 2015
Full Text: PDF file (1.5 MB)
Keywords: Geochemistry; Laterite; Absolute weathering index; Parent rock; Zan; Iran.
Abstract: The Zan lateritic deposit is located in ~25 km southeast of Damavand, Tehran province, Iran. This deposit was developed as stratiform at the base of Shemshak (sandstone and shale) Formation of Jurassic age. Mineralogical data shows that rock-forming minerals in this deposit include kaolinite, diaspore, hematite, goethite, anatase, boehmite, siderite, rutile, quartz, titano-magnetite, zircon and pyrite. The values of absolute weathering index calculated on the assumption of Th as an immobile element indicate that lateritization processes at the Zan were accompanied by enrichment of elements like Al, Fe, Zr, Nb, Ni, Cr, Co, Y, V, and REEs and by leaching-fixation of elements such as U, Mn, Sr, Ba, and Ca. Combination of the data obtained from mineralogical and geochemical investigations reveals that pH variation of weathering solutions, oxidation potential, adsorption, presence of organic matters, preferential sorption by metallic oxides, presence in resistant minerals and fixation in neomorph phases played prominent role in distribution of elements in the Zan lateritic deposit. With considering of correlation coefficients among elements, the minerals such as zircon and rutile can be regarded as potential hosts for REE in the ores. Palaeogeography evidence as well as geochemical indices like TiO2/Al2O3 and Eu/Eu* anomaly suggests that this deposit is a weathering product of basalt.