Depositional environment and regional significance of the sakaka sandstone, northwestern Saudi Arabia
Sharief, Farooq A.
Rogers, John J. W.
Master of Arts
The Sakaka Sandstone of reported Middle Cretaceous age mostly crops out within Al Jawf area, northwestern Saudi Arabia. The formation is mostly sandstone with some siltstone and clay. The purpose of the investigation was to sub-divide the formation into mappable lithologic units and to determine the age of the formation more precisely on the basis of microfaunal study. A detailed petrographic and structural study was attempted to interpret the depositional environment and the source rocks of the formation. In addition, the regional significance of Al Jawf area will be provided from the results of this study. The principal conclusions drawn from this study were: (1) intensive stratigraphic work has delineated several key beds which afford detailed correlation and divide the sediments into three major members; lower, middle, and upper; (2) no microfossils have been reported from microfaunal study, and no surface evidence for reported Middle Cretaceous age has been found (i.e., the lower contact of the Sakaka Formation is conformable and gradational with the underlying sediments of the Lower Devonian); (3) facies analysis suggests that the depositional environment of the formation changed from fluvial deposits in the lower member to windblown deposits in the middle member and to shoreline sediments in the upper member; (4) measurements of directional features indicate a paleocurrent regime from the southeast to west and southwest directions for the sediments of the lower member; from a southwest direction for the sediments of the middle member; and from various direction for the uppermost part of the upper member; and (5) the Sakaka Sandstone was a positive feature of the Jawf-Rutbah arch, and this arch has acted as a partial barrier to the sea from Mesozoic to Early Tertiary times.