PERMIAN AND TRIASSIC GEOLOGICAL HISTORY AND TECTONICS OF THE MIDDLE EAST

The paleogeography postulated from the distribution of Permian and Triassic sedimentary rocks in the Middle East is shown and related to the paleostructure of the region. The Middle East region as defined here includes the Arabian Peninsula, Iran, Iraq, SE Turkey, Syria, Lebanon, Jordan, West Jordan, and the Sinai Peninsula. Within the limits of the area included in this study, a relatively stable pre‐Late Triassic tectonic regime can be recognized and distinguished from a succession of diastrophic events of the Late Triassic epoch, which caused marked changes in the types and distribution of facies. Excluding NE Iran, the Middle East was stable from Late Cambrian to Middle Triassic times, as it formed a part of the Arabian Massif and much of the Middle East Platform, which is a broad shelf bordering the positive Afro‐Arabian Massif to the NE and east. The sediments of this plarform have undergone no strong deformation and have been subjected only to epeirogenic movements which interrupted sedimentation locally or regionally. However, from Upper Permian through Middle Triassic times, the predominant facies on this shelf was carbonates which unconformably overlie the non‐marine or extremely shallow marine elastics of the Lower Permian or older strata in most of the region. Upper Triassic strata in the area are markedly different in facies from older beds because of the movement of blocks in Turkey and northern and eastern Iraq and Iran related to the enlargement and broadening of the Tethys. Asa result, much of northern and eastern Iran were separated from the area to the south and west, which continued to be a shelf flanking the Afro‐Arabian Massif. Consequently, three major structural elements existed in the region: the Arabian Shelf, the Tethyan rift zone and the Paleo‐Tethyan trough.