Lithofacies and Depositional Processes of Submarine Fan System: Early Miocene Syn-Rift Sequence of the Red Sea, NW Saudi Arabia

Abstract

The Burqan Formation of early Miocene age makes up the syn-rift siliciclastic infill by deep-water sediment gravity flow deposits of Midyan Basin, related to the rifting of the Red Sea, northwest of Saudi Arabia. The published work indicates that the Burqan Formation acts as source, reservoir and seal for hydrocarbon accumulations in the subsurface of Midyan region. In the outcrops, this sedimentary sequence is predominantly composed of a thick succession of conglomeratic sandstones of the Nutaysh Member overlain by the mudstone-dominated Subayti Member. Thirteen lithofacies and four facies associations are described and interpreted based upon five comprehensive stratigraphic sections located in the north, west and central part of the basin. The major sub-environments established within the Burqan Formation include channels, channel-levee, lobes and lobe fringes representing proximal and distal parts of the fan respectively. Different sub-environment are randomly stacked within each stratigraphic section which might indicate towards progressive tectonism and coexistence of numerous boulder and sand rich submarine fans. The outcrop lies near the western edge of the basin represent proximal settings based on the presence of abundant boulders, cobbles and pebbly sandstones interbedded with mudstones primarily deposited by cohesive debris flows. Whereas the northern and central segments of the Midyan basin consist of more fine-grained interbedded sand-shale sediments suggesting more distal settings. The main depositional processes that are interpreted for the sediment gravity-flow deposits include cohesive debris flow, concentrated density flows and turbidity currents. The identified lithofacies and their lateral and vertical distribution in this study may act as analog for similar deep marine turbidite reservoir in the subsurface.

AAPG Datapages/Search and Discovery Article #90360 © 2019 AAPG Middle East Region Geoscience Technology Workshop, 3rd Edition of the Siliciclastic Reservoirs of the Middle East, Muscat, Oman, October 28-30, 2019