A Study of Tectonic Subsidence and Sedimentary Sequences in the Nebek Area During the Mesozoic

Abstract

The study conducted in the Nebek area (southwestern Palmyrides),which relied on data the AL-Nabk1 and AL-Nabk2 wells, revealed three main stages of sedimentary basin evolution, designated A, B, and C. These stages correspond, in chronological order, to the Triassic, Jurassic, and Cretaceous periods up to the Turonian stage. Stage A coincides with a period of continuous and significant subsidence during the Triassic, associated with the opening of the Neotethys Ocean, becoming more stable towards its end. Stage B corresponds to a phase of stable basin subsidence in the Early Jurassic, consistent with post-Triassic thermal subsidence. This stage transitioned into uplift during the Middle to Late Jurassic. Stage C commenced with gradual subsidence during the Early Cretaceous, coinciding with a regional marine transgression. This was followed by relatively significant subsidence during the Cenomanian, and then shifted to uplift in the Turonian, which is believed to be related to the initial stages of ophiolite obduction in the northeastern and northern parts of the Arabian Plate. The study identified both regressive and transgressive sedimentary sequences throughout the Mesozoic. Regressive sequences were found to correspond with formations such as korishina dolomite, korishina anhydrite, the upper part of the Kamshuka Formation, and the upper part of the Hiyan Formation. In contrast, transgressive sequences were associated with the Batma Formation, the lower part of the Kamshuka Formation, the Rutbah Formation, the lower part of the Hiyan Formation, the Joudea Formation, and the Rmah Chert. Cross-analysis of subsidence and sequence data indicated that the Ladinian and Cenomanian stages were characterized by exceptionally intense tectonic and sedimentary activity compared to other geological ages within this era.