Diagenetic Evolution of the Kimmeridgian Carbonates of the Arabian Platform (Jubaila and Arab Formations, Saudi Arabia)

Summary The Jubaila and Arab formations, deposited on the Arabian Platform during the Kimmeridgian, comprise shallow-marine carbonates dominated by oolitic shoals and associated lagoonal to peritidal facies. Diagenetic alteration, including multiple phases of calcite, dolomite, and anhydrite cementation as well as locally pervasive dolomitization, has substantially modified the pore framework. Early calcite cements (C1–C3) occur exclusively within the Jubaila Formation and likely precipitated from marine-derived fluids under shallow burial conditions, whereas early dolomitization of peritidal carbonates is confined to the Arab Formation. Burial-stage cements (C4–C5), together with saddle dolomite, are present in both formations. Pore systems are heterogeneous, with cementation exerting the primary control on porosity creation and preservation. Enhanced cementation along anticline flanks, relative to crestal positions, further influences pore-type distribution and reservoir quality. This intricate diagenetic evolution provides key insights into the geological development of the region.