SEDIMENTOLOGY AND MINERAL-COMPOSITION OF THE KURNUB SANDSTONE IN WADI QSIEB, SW JORDAN

The Kurnub Sandstone of Early Cretaceous age crops out in Wadi Qsieb (in the southwest of Jordan) with a thickness of 130 m. Moderately developed fining-upward cycles with irregular erosive bases, together with the presence of plant fragments and the absence of body or trace fossils, point to a fluviatile depositional environment, probably a river of intermediate sinuosity. Results of grain-size analysis confirm this interpretation. The sandstones are compositionally and texturally supermature quartz arenites formed mainly by recycling from Early Palaeozoic sandstones and less commonly by direct supply from the Arabian-Nubian Shield. The absence of feldspars and unstable heavy minerals is attributed to intense chemical weathering, attacking sands that were deposited with a low rate on a craton bordering the Tethys Sea. The thickness recorded here and the absolute absence of hornblende are in contradiction with what has been published by Nasir and Sadeddin (1989).