oa Sudair and Jihl Margin: Development of the Slope and Basinal Deposits in Oman During the Early-Middle Triassic

In Northeast Oman, outcrop equivalents of the Sudair Formation are present and described as Lower Mahil Member, around 250m thick. Its lower part is built mainly of shale, muddy dolomites, microbialite and oncoidal grainstones, whereas the upper part is mainly represented by grainstones. The stratigraphy is poorly constrained and then, mainly by chemostratigraphy. Here we present detailed sections from slope deposits in the Jabal Sumeini area (Wadi Maqam units) to distally tilted blocks (Ba’id), basinal carbonates (Wadi Wasit) and oceanic deep-water deposits (Buday’ah). We present here new result on the stratigraphy and the architecture of the Arabian Platform margin and its interpretation as a slope, oceanic plateau and basin succession, which provides new insights into the evolution of the coeval Sudair and Jihl platforms. It seems that the accumulation rate in the slope and basinal deposits depends on the carbonate export from the platform - high in Smithian and absent or very reduced in Spathian and Anisian time. This infers for the southeastern Arabian platform high carbonate productivity during the Smithian and very reduced during the Spathian and much of the Anisian.