Summary of Tertiary investigations in western Saudi Arabia, current work by the U.S. Geological Survey and recommended future studies

Abstract

In 1936, geologic work related to the Tertiary System in western Saudi Arabia began with a study of the Umm Gerad barite deposit by K. S. Twitchell. In 1944, a study focusing specifically on Tertiary rocks was conducted by Steineke and others near Jiddah. Small-scale mapping of Tertiary sequences began in 1950 in southwestern Saudi Arabia and later in northern 3audi Arabia as part of the Kingdom's early mapping program. These studies were part of a larger program being directed by the Government of Saudi Arabia in connection with mineral resource investigations. In the mid- to late-1960's, the Bureau de Recherches Geologiques et Minieres discovered mineralized Tertiary rocks al Jabal Dhaylan and began a study, which continues to the present, of both the Tertiary rocks and the mineralization. Following a number of early local studies, in 1973 the U.S. Geological Survey began detailed study of the Tertiary layered rocks along the Red Sea coastal plain south of Jiddah. More recently, Riofinex and Seltrust have been exploring for selected commodities in Tertiary sequences of northwestern Saudi Arabia and the Red Sea coastal plain. Results of these studies, including work by the Saudi Arabian Directorate General of Mineral Resources and the Saudi government agency preceding it, are summarized in this report. Characteristics of the Tertiary rocks south of lat 23? N. and the Tertiary mineral deposits of western Saudi Arabia are also summarized. Recommendations are made for future geologic studies and mineral assessment of the Tertiary rocks of western Saudi Arabia.