Using carbon and oxygen isotopes for global correlation in the Early Triassic Lower Mahil Formation, North Oman, despite potentially misleading diagenetic effect

The study probes into the carbon isotope curves of the Lower Triassic Mahil Formation in two sections situated in the Northern Oman Mountains. The primary objective of the research was to understand the relationship between facies and isotopes, involving the analysis of 174 micrite samples for oxygen and carbon isotopes. Strict measures were implemented during sample selection to mitigate potential influences such as cracks or weathering. The results unveiled diverse δ13C values within the same facies, indicating inconsistencies in carbon isotope trends. Intriguingly, despite notable diagenetic alterations, particularly in the Saiq Plateau section, the Lower Mahil Formation retained carbon isotope patterns with minimal diagenetic impact. However, a note of caution is warranted in the widespread application of these findings, as utilizing whole rock data for carbon isotope analysis may introduce uncertainties. Despite potential diagenetic effects, the carbon isotope records of the Lower Mahil Formation remain valuable for comprehending patterns associated with KS1, facilitating comparisons between local and regional carbon isotope signatures. This research contributes significantly to establishing correlations between outcrop and subsurface data, offering valuable insights into variations in Lower Triassic carbon isotopes. •Variation of carbon isotopes in Early Triassic with an example from Khuff Formation•Homogenous intense diagenesis may use carbon isotopes globally.•High-resolution 50 cm scale sampling yields a better carbon isotope vertical trend.•Such a high resolution helped in better later correlation, proximal to distal.