This study presents a detailed microfacies analysis, a δ 13C and δ 18O values from whole-rock samples, and spectral gamma-ray records of the Lower Triassic (Induan) Mahil Formation (Khuff outcrop equivalent (KS-1)) in Jabal Akhdar, at the Saiq Plateau section and Wadi Sahtan section, in Northern Oman. The two sections were measured and sedimentologically logged along a depositional dip direction emphasizing color, lithology, grain component, bed thickness, nature of bed contact, lateral continuity of bed, and fossil content. One hundred seventy nine fresh rock samples were collected from various lithofacies every 0.5 m. Moreover, high-resolution spectral gamma-ray measurements were taken at every 10 cm from both logged sections. The collected samples were polished and powdered for carbon and oxygen isotope chemostratigraphy analysis. Furthermore, the collected samples were thin sectioned after blue epoxy impregnated, and then they were half stained with Alizarin Red S and Potassium Ferricyanide for mineralogical identification. The point-counting model compositions were carried out by counting 300 points for each thin section to reconstruct the origin components, obtain precise quantification, develop reflectable microfacies, and construct the depositional model for the Lower Mahil Formation. Moreover, the high-resolution carbon isotope data integrated with the high-resolution spectral gamma-ray data to build a robust stratigraphic framework for the Lower Mahil KS-1 Formation. Consequently, twenty-four microfacies were identified; four are only recognized in the Wadi Sahtan logged section, twelve are restricted to the Saiq Plateau logged section, and eight are common for both sections. The Mahil Formation consists of backshoal to foreshoal carbonate facies, with shoal facies restricted to the Saiq Plateau logged section. The backshoal facies was characterized by abundant non-skeletal grains with breccia. The shoals were predominantly oolitic intraclasts and foraminiferal packstone-grainstone. Foreshoal carbonate facies, on the other hand, has mixed skeletal and non skeletal grains with weakly developed hummocky cross-stratified beds. Moreover, five fourth-order depositional sequences were identified based on stable carbon isotopes, uranium, and total gamma-ray profiles. Four of them are complete, showing transgression and regression phases, and one is incomplete comprise only a transgressive phase. The δ 13C curve of the Lower Mahil KS-1 Formation can be correlated with the others around the Tethys, indicating that the Lower Mahil KS-1 Formation represents the near-primary signal of C isotope variations of the coeval seawater thus could be considered as a reference section for further studies.