PRECIOUS METALS OF THE BASSIT OPHIOLITE COMPLEX (NORTHWESTERN SYRIA) - CONTENTS AND PROSPECTS

The precious metal contents were first studied in all main rock types of the Bassit Mesozoic island-arc-type ophiolite association (western Syria): ultrabasic complex (ultrabasites and chromitites), gabbro comp lex (layered gabbro-norites and massive coarse-grained gabbro-norites) , gabbro-diabases, parallel dike complex, aplites, pillow-lavas, and a pogabbroic crusts of weathering. The platinum-group elements (PGE) are here represented by Pt and Pd, with Pd markedly predominant. The rock s studied are characterized by very low Ru and Rh contents, which with rare exception are beyond instrumental sensitivity. Ir was not found in any of the samples studied. Results obtained generally agree with d ata on other ophiolite associations, although the Bassit gabbroids and chromitites are characterized respectively by higher and lower averag e PGE and gold contents compared to other complexes. The PGE behavior is similar to that in Paleoproterozoic layered intrusions that origina ted as a result of boninitic melt crystallization. Since some of the r ocks studied contain as much as 0.85-115 ppm PGE, this ophiolite assoc iation can be considered promising for platinum. The prospects are als o confirmed by the elevated PGE content in the pillow-lavas, which are probably comagmatic to the gabbroids. The absence of proper PGE miner als in the rocks, a factor which can be partly explained by the small number of samples studied. The gold contents are typically correlated with PGE but do not exceed 0.05 ppm. The precious metal contents incre ase noticeably in laterites after gabbroids, especially that of platin um. This fact also supports the precious metal potential of the region .