Structural Evolution of the Rub' Al-Khali Basin, Saudi Arabia

Abstract

Reflection seismic data from the Rub' al-Khali of Saudi Arabia are interpreted and synthesized for the first time into a map of basement structure and model for the kinematic evolution of the basin. The deepest imaged structures are undrilled Precambrian basins filled with layered strata at depths up to 10 km. The reflection seismic interpretation was integrated with regional gravity and magnetic data. Structural style varies with location in the basin. Precambrian outliers below the continuous Phanerozoic megasequences are rift basins recording Precambrian and Phanerozoic inversion. Phanerozoic basement tectonics involved a combination of long wavelength structural arches and basins plus more discrete compressional and transpressional structures. Discrete compressional structures formed in the Cretaceous and Tertiary. Cretaceous deformation is most pronounced on NE-SW trending structures in the east of the basin, their magnitude increasing with proximity to the Oman Cretaceous obduction and thrust belt. Tertiary fold reactivation in response to Arabian plate suturing along the Zagros orogen is most pronounced on NNW trends, particularly in the center of the basin. Most structures are hard linked from the basement to upper fault tips and folds, and there is little geometric evidence for the influence — and therefore presence — of evaporites on structural style, although there are minor indications in an area termed “East Rub' al-Khali Salt Basin.” These evaporites mark the western edge of the Ediacaran-Cambrian Hormuz salt basin. Kinematic modelling indicates the folds may be forced structures developed above reverse faults that sole into mid-crustal basement fabrics. Basement is undrilled and unexposed in the Rub' al-Khali, but a tentative map of basement terranes is derived from domains of Phanerozoic reactivation trends combined with gravity and magnetic modelling. Defining basement structure impacts hydrocarbon exploration in several ways. The presence and position of deep faults creates compartmentalization and charge migration pathways relevant to Lower Paleozoic fairways. Paleozoic arches and basins set up architectures of Devonian and Triassic fairways, including unconformity and onlap trap elements. Cretaceous and Tertiary structures are relatively simple, large periclines, some of which contain proven giant hydrocarbon fields.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015