Reconnaissance geochemical exploration of plutons of syenite and shonkinite, southern Asir, Kingdom of Saudi Arabia

Abstract

Reconnaissance geochemical exploration for rare metals in plutons of syenite and shonkinite disclosed generally less than 20 ppm Nb in rocks, wadi sediments, and concentrates. The sparsity of Nb is accompanied by low values for La, Sn, W, Y, and Zr and relatively high but insignificant values for Be and Mo. Base and precious metals are either below their respective limits of determination in the various sample media or are present at background levels commensurate with average crustal abundances in felsic rocks. Pegmatite dikes associated with the syenite plutons are rare and lack vermiculite.The present investigation disclosed no possible ore deposits in the plutons covered by the field work.Known kyanite-topaz-natroalunite rocks in the vicinity of the surveyed areas should be examined for possible deposits of Cu, Mo, or Au associated with high-alumina hydrothermal depos its.