Lithofacies and Geochemical Analyses of Lower Triassic Upper Khartam Member of the Khuff Formation: An Outcrop Analogue for the Permo-Triassic Khuff Reservoirs, Saudi Arabia

Abstract

Sedimentological and stratigraphic investigations were carried out on outcrop sections of the Lower Triassic Upper Khartam Member, Khuff Formation in the central region of Saudi Arabia. Ten lithofacies interpreted as products of marine transgression, foreshoal, shoal complex, shoal fringes, back shoal, tidal flat and supratidal flat depositional environments are identified in a 31-m thick composite section of this formation. On the basis of their vertical stacking patterns, these lithofacies are grouped into five high frequency sequences(HFS); HFS 1 (at the base) to HFS 5 (at the top). Background storm influence in the deposition of the Upper Khartam lithofacies is indicated by the presence of gutter and pot casts, wavy beds, lenticular beds and several types of soft sediment deformations. Ooids are present in all the identified lithofacies. The ooids grain size increases with increasing depositional energy. This trend enables us to link ooids size with their depositional environments which in turn, allows for the prediction of the geometry and nature of pores in the lithofacies. The distribution patterns and concentrations of trace elements and oxides follow the vertical stacking patterns of the lithofacies in the composite sequence. These geochemical proxies are highly concentrated in the nearshore depositional environments (marine transgression, tidal flat, and supratidal flat) lithofacies but their enrichment diminished in the offshore (foreshoal, shoal bars, and distal backshoal) depositional environments.

AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014