Distribution and Significance of Sulfur-Containing Compounds in Upper Cretaceous Black Shales from the Eastern Desert, Egypt

Abdullah, Eman Saied; Mohammed, Hoda Abdelazeem; El Agroudy, Ibrahim S; Rashad, Ahmed M; Masod, Mohamed Bakry; Kishway, Adly Fathi; Ebaad, Mohamed A

doi:10.21608/ejchem.2025.379835.11686

Distribution and Significance of Sulfur-Containing Compounds in Upper Cretaceous Black Shales from the Eastern Desert, Egypt

Document Type : Original Article

Authors

¹ Evaluation Department, Egyptian Petroleum Research Institute, Nasr City, Cairo

² Analysis and evaluation department,Egyptian petroleum research institute (EPRI),Cairo,Egypt

³ Exploration Deparment, Egyptian Petroleum Research Institute

⁴ analysis and evaluation department, Egyptian Petroleum Research Institute, Nasr City, Cairo, Egypt.

⁵ Egyptian Petroleum Research Institute, Analysis and Evaluation department

⁶ Egyptian Petroleum research Institute

⁷ Analysis and Evaluation Department, Egyptian Petroleum Research Institute, Nasr City, Cairo, Egypt

10.21608/ejchem.2025.379835.11686

Abstract

Black shale serves as a vital energy resource, a glimpse into Earth's history, and an essential element for comprehending geochemical and environmental processes. Organic geochemical studies of black shale provide insight into various geological aspects including age, source rock type, depositional environments, type and source of organic matter in addition to hydrocarbon potential. In this study, we aim to assess the distribution of various sulfur-containing organic compounds as indicators of lithology, paleoenvironmens and thermal maturity of organic matter. This study utilized shale samples from the Dawui Formation, an important Upper Cretaceous sedimentary formation in Egypt. Black shales extracts were fractionated into their saturate, aromatic, resin and asphaltene (SARA). Aromatic fractions were examined via GC-MS employing selective ion monitoring mode (SIM) tailored for aromatic sulfur-containing compounds, including dibenzothiophenes (m/z 184), methyldibenzothiophene (m/z 198), dimethyldibenzothiophen (m/z 212) and trimethydibenzothiphene (m/z 226) in addition to phenanthrene (m/z 178). The ratios of DBT/P for the studies samples were found to be more that unity indicating carbonate-dominated lithofacies and marine depositional contexts. This is supported by the results of (1+4)-/(2+3)-MDBT ratios which were found to be > 2.70.. The higher proportions of the more thermally stable isomers to the less one were applied for assessing thermal maturities. The higher ratio of 2,4,6-/(2,4,7-+2,4,8)-TMDBT in addition to 4-MDBT/1-MDBT have been applied indicating significant maturities of the studied samples. The obtained results highlighted the effectiveness of applying the distribution and relative abundance of specific thiophenes, along with their link to other identified isoprenoid biomarkers as reliable indicators of the paleoenvironment, lithofacies and maturity assessments.

Keywords