Quantitative bathymetry reconstruction of the Late Jurassic Arabian Intrashelf Basin

Abstract

Realistic bathymetric reconstructions of paleo-basins are fundamental to interpretations of accommodation space, sediment accumulation patterns, and basin-infill processes. This study presents a quantitative paleo-bathymetric reconstruction of the Late Jurassic (Callovian–Kimmeridgian) Arabian intrashelf basin, containing the Tuwaiq Mountain, Hanifa, Jubaila and Arab Formations. Despite extensive previous research, estimates of paleo-water depths in the Arabian intrashelf basin cover a wide range leading to uncertainty in depositional environments and contentious interpretations. Our reconstruction integrates 2 key outcrop sections and 19 published subsurface wells, while incorporating the latest regional geological frameworks and interpretations. A critical component of the workflow is isostatic adjustment using Airy isostasy to account for sediment loading-induced subsidence. Our quantitative reconstruction suggests a paleo-basin water depth ranging from 42 to 95 m during lowstand and early transgression/late highstand phases to 65 to 104 m during late transgressions-early highstands. It reveals an asymmetric geometry that influences basin-infill processes: The western margins exhibit gentler depositional slopes (<0.03°), facilitating extensive eastward progradation of shallow-water carbonates of up to 400 km into the basin. The steeper eastern margins (0.05°–0.06°) experienced limited westward progradation of only about 100 km. The asymmetry of the basin leads to higher source rock richness and enhanced organic preservation potential towards the eastern depocenter. Ultimately, the topography was levelled during the late Kimmeridgian with the deposition of the Jubaila and Arab Formations. With refined paleo-bathymetries, we provide improved geological constraints for predicting facies distribution and properties, ultimately benefiting future exploration and sustainable subsurface resource developments within this economically significant region.