Akademik Veri Yönetim Sistemi
GEOCHIMICA ET COSMOCHIMICA ACTA, cilt.61, sa.15, ss.3161-3169, 1997 (SCI-Expanded)
We have analyzed the boron isotope composition of 80 borate minerals (major minerals: borax, colemanite, and ulexite; minor minerals: veatchite-A, tunellite, kernite, terrugite, probertite, meyerhofferite, inderite, inyoite, hydroboracite, howlite, and pandermite) from the main deposits (Kirka, Bigadic, and Emet) and two smaller deposits (Kestelek and Sultancayir) in the western Turkish borate deposits. Forty-three samples were also analysed for their Sr isotope composition. The data span a wide range in delta(11)B values from -1.6 parts per thousand to to -25.3 parts per thousand. The delta(11)B values of the main borate minerals are largely controlled by their mineralogy and the pH of the brines from which they precipitated. An inverse correlation between the average delta(11)B and Sr-87/Sr-86 ratios of colemanite in the different deposits suggests there is some variation in the sources of boron and Sr to the deposits. Emet has the highest contribution from aluminosilicates and Kirka the highest contribution from Eocene carbonates, with Bigadic occupying an intermediate position. The delta(11)B values of the minor borate minerals distinguish between those which are primary precipitates from the original brines (or formed from primary berates without boron loss from the system) and those which formed from alteration of preexisting borate minerals with substantial loss of boron from the system. Copyright (C) 1997 Elsevier Science Ltd.