Source Rock Potential and Organic Geochemistry of the Early Jurassic Datta Shales, Potwar Sub‐Basin, Pakistan: Correlations in the Toot Oilfield

ABSTRACT The siliciclastic deposits of the Datta Formation, located along the northwestern margin of the Indian Plate, adjacent to the eastern Tethys Ocean, record a crucial paleoenvironmental transition from fluvio‐deltaic to shallow marine settings. A comprehensive geochemical investigation was carried out to assess the source rock potential of Datta Shales in the Potwar Sub‐Basin (Psb). This study involved total organic carbon (TOC) measurement, Rock Eval pyrolysis, vitrinite measurements, organic petrography, and detailed biomarkers analysis to examine the origin of organic matter (OM), depositional conditions, thermal alteration, along with oil–oil and oil–source correlation using core and well‐cuttings data from the Toot‐17 well. Geochemical evaluation indicates that a substantial portion of Datta Shales demonstrates fair to good potential and is thermally mature, characterised by type‐III kerogen with vitrinite dominated maceral composition. However, a fraction of Datta shale with Hydrogen Index values less than 50 mgHC/g TOC contains type‐IV kerogen with predominantly inertinite maceral. The biomarker composition and microscopic analysis indicate that the OM is primarily terrestrial in origin and was deposited in shallow marine‐influenced settings under relatively suboxic conditions. The stereoisomeric composition of steranes and terpanes indicate that the thermal maturity of the samples falls in the late oil window. The star correlation diagrams and cluster analysis for oil‐source correlation exhibit significant differences between crude oils and the Datta shale samples, thereby suggesting that the crude oils from Toot oilfield and the Datta Shales of Toot‐17 are not genetically associated.