Crustal control on basement uplift beneath the Ghawar Anticline, Saudi Arabia—gravity modeling with receiver function constraints (original) (raw)

Arabian Journal of Geosciences

Abstract

The Ghawar Anticline (GA) belongs to super-giant Rayn Anticlines in Eastern Saudi Arabia (ESA). The origin of GA is ascribed to basement-uplift, although, its evolution remains obscure due to inadequate knowledge on configuration of deeper crust and role of crust in producing the basement uplift. The nature of deeper crust is comprehended by an integrated crustal model utilizing DEM, Bouguer anomaly (BA) map, and high-pass-filtered residual BA map by using Laplacian operator, tilt derivative, theta maps, and Euler 3D convolution map on BA data. These maps prove helpful in delineating the structural outline of GA and its edge detection of the uplifted basement against the adjoining sub-basins. 2D gravity inversion for a traverse represents a model on subsurface mass anomalies extending from basement to Moho depth, for which, constraints are utilized based on the nature of seismogenic crust in ESA and available results of receiver function for four seismic stations. A 3-layer source on mass anomalies with depths of 3–5, 22.5, and 40 km is inferred. Poisson’ ratio based on Vp/Vs values is high: 0.41–0.42 on its limbs to 0.44 at its median part, where the receiver function data reveals a zone of mantle uplift. Main results derived from Integrated Gravity Model underlying the traverse are as follows: (i) Moho is uplifted by ~ 9 km below GA, for a 220-km width, (ii) the zone of basement uplift in the top crust is ~ 4.5 km over a distance of ~ 75 km, where deep-penetrative faults assist the basement uplift, and (iii) a higher thermal regime probably influenced the crustal configuration below GA.

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