Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation

Al-Auqadi, Rahma Sael; Mamaseni, Wrya J.; Mahdi, Adnan Q.; Akram, Revan K.; Makled, Walid A.; Al-Juboury, Ali Ismail; Gentzis, Thomas; Kamel, Asmaa; Omar, Nagham; El Garhy, Mohamed Mahmoud; Alarifi, Nasir

doi:10.3390/min15111202

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Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation

by

Rahma Sael Al-Auqadi

¹

,

Wrya J. Mamaseni

²,

Adnan Q. Mahdi

³,

Revan K. Akram

⁴,

Walid A. Makled

⁵

,

Ali Ismail Al-Juboury

⁶,

Thomas Gentzis

^7,*

,

Asmaa Kamel

⁸,

Nagham Omar

⁹,

Mohamed Mahmoud El Garhy

¹⁰ and

Nasir Alarifi

^11,*

¹

College of Petroleum and Mining Engineering, University of Mosul, Mosul 41002, Iraq

²

Department of Earth Sciences and Petroleum, College of Science, Salahaddin University-Erbil, Erbil 44001, Iraq

³

Department of Oil and Gas Economics, College of Administrative and Financial Sciences, Imam Jaafar Al-Sadiq University, Kirkuk 36001, Iraq

⁴

Department of Petroleum Technology, Erbil Technology College, Erbil Polytechnic University, Erbil 44001, Iraq

⁵

Exploration Department, Egyptian Petroleum Research Institute (EPRI), 1 Ahmed El Zomor St., Nasr City, Cairo 11727, Egypt

⁶

Petroleum Engineering Department, Al-Kitab University, Kirkuk 36001, Iraq

⁷

Core Laboratories, Houston, TX 77040, USA

⁸

Earth Science Department, Faculty of Science, Damanhour University, Damanhour 22511, Egypt

⁹

Institut fur Geowissenschaften—Geologie, University of Bonn, 53115 Bonn, Germany

¹⁰

Geology Department, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt

¹¹

Geology and Geophysics Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia

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Minerals 2025, 15(11), 1202; https://doi.org/10.3390/min15111202

Submission received: 29 September 2025 / Revised: 10 November 2025 / Accepted: 11 November 2025 / Published: 14 November 2025

(This article belongs to the Section Mineral Exploration Methods and Applications)

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Abstract

This study provides the first comprehensive characterization and classification of organic microfacies within the globally significant Jurassic hydrocarbon source rocks of Iraqi Kurdistan. This study aims to resolve the knowledge gap in the Jurassic source rocks of northern Iraq by establishing the first organic microfacies classification scheme, utilizing an integrated petrographic and geochemical approach to reconstruct the regional paleoenvironmental evolution and confirm the source rock’s petroleum potential. The Middle–Late Jurassic Sargelu, Naokelekan, and Barsarin formations were investigated using samples from the Mangesh-1 and Sheikhan-8 wells. Using cluster analysis, we identified five distinct organic microfacies (A–E). Microfacies A (highly laminated bituminite), B (laminated/groundmass bituminite), C (laminated rock/lamalginite), and D (massive organic-matter-rich) show the highest hydrocarbon generation potential. The findings reveal a clear paleoenvironmental evolution: the Sargelu Formation was deposited in anoxic open marine conditions (microfacies C, D); the Naokelekan Formation represents a progressively restricted silled basin with intense anoxia leading to condensed sections dominated by microfacies A, which shows the highest source rock potential; and the Barsarin Formation reflects increasing restriction and hypersalinity, showing diverse microfacies (B, C, D, E) that captured variations in marine productivity and terrigenous influx. Principal component analysis (PCA) quantitatively modeled these paleoenvironmental gradients, aligning the distinct organic microfacies and their transitions with conceptual basin models. Geochemical analysis confirms that the organic matter is rich, predominantly Type II kerogen, and thermally mature, falling within the oil window. The presence of solid bitumen, both in situ and as evidence of migration (microfacies E), confirms effective hydrocarbon generation and movement. This integrated approach confirms the significant hydrocarbon potential of these Jurassic successions and highlights the critical role of specific organic microfacies in the region’s petroleum system, providing crucial guidance for future hydrocarbon exploration in northern Iraq.

Keywords: organic microfacies; Jurassic of northern Iraq; thermal maturity; biomarker geochemistry; carbonate source rock; hypersaline source rock

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MDPI and ACS Style

Al-Auqadi, R.S.; Mamaseni, W.J.; Mahdi, A.Q.; Akram, R.K.; Makled, W.A.; Al-Juboury, A.I.; Gentzis, T.; Kamel, A.; Omar, N.; El Garhy, M.M.; et al. Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation. Minerals 2025, 15, 1202. https://doi.org/10.3390/min15111202

AMA Style

Al-Auqadi RS, Mamaseni WJ, Mahdi AQ, Akram RK, Makled WA, Al-Juboury AI, Gentzis T, Kamel A, Omar N, El Garhy MM, et al. Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation. Minerals. 2025; 15(11):1202. https://doi.org/10.3390/min15111202

Chicago/Turabian Style

Al-Auqadi, Rahma Sael, Wrya J. Mamaseni, Adnan Q. Mahdi, Revan K. Akram, Walid A. Makled, Ali Ismail Al-Juboury, Thomas Gentzis, Asmaa Kamel, Nagham Omar, Mohamed Mahmoud El Garhy, and et al. 2025. "Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation" Minerals 15, no. 11: 1202. https://doi.org/10.3390/min15111202

APA Style

Al-Auqadi, R. S., Mamaseni, W. J., Mahdi, A. Q., Akram, R. K., Makled, W. A., Al-Juboury, A. I., Gentzis, T., Kamel, A., Omar, N., El Garhy, M. M., & Alarifi, N. (2025). Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation. Minerals, 15(11), 1202. https://doi.org/10.3390/min15111202

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Classification and Depositional Modeling of the Jurassic Organic Microfacies in Northern Iraq Based on Petrographic and Geochemical Characterization: An Approach to Hydrocarbon Source Rock Evaluation

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