Geochemistry of the Igdekoy-Doganlar Na-Ca borate deposit, Emet Province (western Anatolia, Turkey)

Abstract

Borates at the Igdekoy-Doganlar locality were deposited in a Miocene lacustrine environment during periods of Paleogene to Early Quaternary volcanic activity. The mineral paragenesis consists of probertite – (NaCaB₅O₇(OH)₄.3H₂O), ulexite (NaCa[B₅O₆(OH)₆].5H₂O), hydroboracite (CaMg[B₃O₄(OH)₃]₂.3H₂O), colemanite (Ca[B₃O₄(OH)₃].H₂O), halite, anhydrite, glauberite, smectite and illite. The major element, Ca, is higher in the Igdekoy-Doganlar deposits compared to the averages for andesite and the Earth’s crust. Within the trace elements, notable enrichment is identified in Li, Se, As, Sb, Sr and Cs. Lithium and Se occur in sufficient concentrations to be considered as economically valuable by-products. B and Sr anomalies can be used as an important marker in the exploration for boron deposits. The Y/Ho ratio of the Igdekoy-Doganlar borates is close to chondritic values. The negative Ce anomaly in borates from the Igdekoy-Doganlar deposit suggests that deposition occurred under oxidative conditions. The Eu and Ce anomalies reflect a hydrothermal contribution of REE. Geochemical and geological data suggest that the Igdekoy-Doganlar borate deposits were formed in high-pH playa lakes that were discharged from volcanic and terrestrial environments under evaporative conditions due to the effect of arid-semi arid climate.