No abstract

This program would not have been possible without the excellent support of all agencies involved, both in Pakistan and the United States. The geological information and institutional growth obtained through this program should contribute significantly toward orderly economic and scientific development in one of Asia's largest and newest nations.

Geochemical reconnaissance for rare metals in plutons of albite-muscovite granite and quartz monzonite in the vicinity of Jabal Lababa disclosed positive geochemical anomalies for beryllium, tantalum, thorium, lanthanum, niobium, tin, yttrium, and zirconium. The low anomalous values for the rare metals in rocks and the short mechanical dispersion trains, seldom exceeding 4 km in length, of rare-metalbearing heavy minerals, are interpreted to indicate that primary deposits of these metals are lacking, and any placers would be small and low in tenor. Small positive anomalies for barium were detected at scattered localities in the metasediments adjacent to the plutons in the Jabal Lababa area. Positive anomalies for the precious metals are lacking, and the low values observed for base metals do not indicate the presence of sulfide deposits. The abundant quartz lag gravel in the eastern part of the area is unmineralized. Small books of muscovite are present in some pegmatite, but is of non-commercial volume and quality. A subcircular structure at the coast of the Red Sea near the mouth of Wadi Nahb should be tested to determine if it is a buried salt dome. Three nonmagnetic high-density concentrates containing 1,000 to 15,000 ppm lead were found on the granitic pluton near Ar Rayth. The source of the lead is not galena, and high values for lead appear to be characteristic of the pluton but do not indicate an ore deposit.

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.