Writers : Abedini, A.; Calagari, A. A.
Refference : Scientific Quarterly Journal Geosciences, No. 72, Page:145-154
Publishing Year : 1388

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 fıve 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 vveathering 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 fıxation 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 vveathering solutions by carbonate bedrock, mineralogical control, and pH changes of the environraent are the most important controlling factors in the distribution of LREE, HREE, HFSE, LILE and TTE during lateritization processes at Kanisheeteh.

Subject List : Ree elements