Главная – Журналы – Геология и геофизика 2018 номер Неопубликованное

Smectite illitization geothermometry has been used to assess the thermal maturity and hydrocarbon generation potential of the Late Paleocene to Early Eocene Patala Formation in the Upper Indus Basin. X-ray diffraction (XRD) detected illite, muscovite, quartz, kaolinite, chlorite, and calcite. Comparison between air-dried (AD) and ethylene glycol (EG)-solvated XRD patterns reveal the absence of discrete smectite and interstratified illite-smectite (I-Sm). Additionally, authigenic illite-2M₁ indicates that the Patala Formation has entered a late-stage diagenetic zone or low anchizone which lies in the R3 illitization zone. Abundant SiO₂ and Al₂O₃ in the Patala clay fraction indicate the substitution of tetrahedral Si⁴⁺ by Al³⁺ within the smectite interlayers. Likewise, the relative abundance of K₂O to CaO and MgO indicates the exchange of K⁺ with Ca²⁺ and Mg²⁺ during smectite illitization. Scanning electron microscopy (SEM) reveals in-situ growth of platy illite crystals that form within the R3 zone. Furthermore, the total organic carbon (TOC) of the Patala shale exposed in Tirah suggests a poor to good source rock. The absence of discrete smectite and I-Sm, combined with the detection of discrete illite in the Patala shale, suggests that hydrocarbon might have potentially migrated from the source to the reservoir rock during smectite illitization.