Abstract
The lower Eocene-lower Miocene succession in the central part of the Al Jabal Al Akhdar, northeast Libya was investigated to determine its depositional environments and shed some light on diagenetic alterations. This succession is composed mainly of carbonate rocks and includes five formations from base to top; the Apollonia, Darnah, Al Bayda, Al Abraq, and Al Faidiyah. Relatively uniform shallow-marine carbonates were accumulated across northeast Libya, including the study area. Facies analysis of the studied carbonate rocks enables determination of four shallow-marine carbonate facies associations. These facies associations are: (1) restricted lagoon with limited circulation at/or below fair-weather wave base, (2) lagoon with open circulation below the fair-weather wave base, (3) platform-margin reefs, and (4) continental slope setting between the fair-weather and storm wave bases. The abundance of shallow marine carbonates indicates the presence of epeiric or epicontinental sea that covered the whole northern Africa. The depositional history in the studied area was controlled primarily by tectonics and relative sea-level changes. Four unconformities (i.e., sequence boundaries) were observed and separating five depositional sequences in the studied succession. Each depositional sequence shows shallowing-upward trend. The recorded unconformities reflect episodes of non-deposition and/or erosion and are associated with major fall in eustatic sea level. The diagenetic processes of the studied carbonate rocks include; micritization, pyritization, compaction, cementation, aggrading neomorphism and partial dissolution.
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Acknowledgements
The authors would like to thank Prof. Adam El Shahat, Mansoura University for his careful reading and discussion that improve the manuscript. Also authors thank Prof. Abdallah Shahin, Mansoura University for identification of the observed microfossils in thin sections. Our thanks are due to anonymous reviewers for their critical comments that improved the manuscript.
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Anan, T., Gheith, A. & Hassan, S. Facies analysis and depositional environments of the lower Eocene–lower Miocene succession in Northeast Libya. Carbonates Evaporites 36, 50 (2021). https://doi.org/10.1007/s13146-021-00706-9
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DOI: https://doi.org/10.1007/s13146-021-00706-9