Abstract
This paper discusses the petrographical and paleontological characteristics of the exposed siliceous (chert nodules) at Al Jabal al Akhdar in northeast Libya. Cherts are found in four rock units and at four superimposed horizons: Al Athrun Formation (Campanian–Maastrichtian) is the oldest one which is overlain by Apollonia Formation (Early–Middle Eocene), then Darnah Formation (Middle–Late Eocene) and Wadi al Qattarah Formation (Late Miocene) the youngest formations. This study is based on field observation and petrographical and paleontological examinations of both chert nodules and hosting limestone rock. Petrographically, the source of the silica in the chert nodules of the Al Athrun Formation is proved to be from silica-rich fluid due to the radiolarian. However, in Apollonia Formation, the sponges seem to be the source. Meanwhile, Darnah Formation and Wadi al Qattarah Formation are suggested to be secondary in origin (i.e., diagenetically is evidenced in the silica replacement to shells). Therefore, further study using more petrographical and paleontological samples will be demanded in order to confirm the biogenic source of Darnah and Wadi al Qattarah formations.
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Acknowledgements
The authors are grateful to the staff members of both Earth Sciences Department of University of Benghazi and Exploration Department of Arabian Gulf Oil Company (AGOCO) for their valuable comments and supports. Our appreciation is due to the late Walid ElKhfifi for the assistance in thin section photographing. Dr. Haidoub is also appreciated for the English review of the manuscript. Our thanks are also extended to the Geological Laboratory of the University of Alexandria, in Alexandria, Egypt for thin section preparations.
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Responsible Editor: Domenico M. Doronzo
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Bakar, M.A., Muftah, A.M. & Shaltami, O.R. Origin of cherts in Al Jabal al Akhdar, northeast Libya: petrographical and paleontological evidences. Arab J Geosci 14, 763 (2021). https://doi.org/10.1007/s12517-021-07002-9
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DOI: https://doi.org/10.1007/s12517-021-07002-9