Geochemistry of Javanmard bauxiticlateriticores, NE Bukan, West-Azerbaijan Province

Javanmard residual horizon is located about 25 km NE of Bukan، West-Azerbaijan Province. This horizon developed، as a stratiform deposit، between Ruteh (Middle-Late Permian) and Elika (Triassic) carbonate formations. It consists of three lithological units: (1) ferruginous laterite، (2) siliceous bauxite and (3) bauxitic clay. Function of weathering processes in the course of formation of this residual horizon caused leaching of Si، Na، Mg، Mn، P، Ca، Sr، Hf، and HREEs، enriching of Al، Ti، V، Cr، Ni، Y، Nb، Zr، U، and Th، and leaching-fixing of Fe، K، Rb، Ba، Co، and LREEs. Geochemical data indicate that the carbonate bedrock played a dual role in distribution of elements. By neutralizing the acidic weathering solutions، the carbonates caused precipitation of Fe as hematite and goethite. These minerals، in turn، resulted in relatively high concentration of V، Cr، Co، LREEs، and Th in ferruginous laterite by adsorption and scavenging processes. These rocks caused these elements to be moved out of residual horizon by forming carbonate stable ionic complexes with HREEs. In addition، variations in pH of weathering solutions، mineral control، and presence of humic and carbonic acids played conspicuous role in the mode of distribution pattern of elements in this horizon.