Abstract: Sedimentology And Sequence Stratigraphic Analyses Of Wajid Sandstone, Asir Region, Saudi Arabia

BABALOLA, LAMEED OLABODE, King Fahd University of Petroleum and Minerals, Department of Earth Sciences, Dhahran 31261, Saudi Arabia

The Paleozoic Wajid Sandstone outcrops in the southwestern part of the Kingdom of Saudi Arabia. Up to date, very limited studies exist on its sedimentology and stratigraphy. The current study focuses on the provenance, depositional environments and sequence stratigraphy of the Wajid exposed in the Abha - Khamis Mushayet area of the Asir Region, Saudi Arabia.

The Wajid is composed of crossbedded arkosic and quartz sandstone interbedded with conglomerates, ironstone, kaolinite rich silty claystone and micrite in places. Two lithofacies were recognized based on detailed field investigation, petrographic and microanalytical analyses using electron microscopy (SEM), X-ray defractometry (XRDEDX) and ICP. The lower unit is predominantly composed of coarse quartz grained iron rich red-brownish sandstone while coarse to medium grained light colored sandstone constitutes the upper unit.

A proximal source was indicated by the presence of angular fragments of claystone and clasts of felsic igneous and low-medium grade metamorphic rocks. Paleocurrent data showed distinctive bimodal current directions in the successions. The paleocurrent data, sand body geometry and dominant mineralogy strongly suggest a braided river sequence characterized by proximal provenance. The occurrences of thin silty claystone and micrite within the sand bodies showed good potential for sequence stratigraphic analysis. The results of this aspect will be available soon.

AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid