Proterozoic tectonism of the Arabian Shield

New field and analytical work, together with a new aeromagnetic map and a geologic, structural, geochemical, and geochronologic synthesis and reappraisal, offer a new view of the anatomy and geologic history of the Arabian Shield. Although Early Proterozoic rocks have been found in the eastern part of the Shield, the main geologic evolution of the Shield is limited to a period ranging from 900 to 530 Ma that led to the formation, amalgamation, and final cratonization of several tectonostratigraphic terranes. The pre-Panafrican structures (>690 Ma), which are difficult to decipher due to younger deformation, were essentially the result of the formation, amalgamation, and accretion of these terranes. The Panafrican tectonism (690–590 Ma) was marked by the formation of the Nabitah Belt and peripheral ranges punctuated by gneiss domes. Various sedimentary formations contemporaneous with this tectonism represent foreland or intracontinental molasse basins. After the Panafrican tectonism, widespread extension (590–530 Ma) brought about crustal thinning that generated bimodal magmatism and significant dike swarms; associated volcanics form the Shammar group. A marine transgression, associated with passive-margin-type structures with tilted blocks, marked the end of the thinning. The platform facies produced by this transgression correspond to part of the Jibalah Formation. Other basins formed as deep continental pull-apart basins along transform faults. This updated view of the Arabian Proterozoic geodynamic evolution provides a framework for reviewing the associated mineralizing events, and places them in a new chronology and structural history.