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Geology, biostratigraphy and carbon isotope chemostratigraphy of the Palaeogene fossil-bearing Dakhla sections, southwestern Moroccan Sahara

Published online by Cambridge University Press:  26 October 2017

MOULOUD BENAMMI*
Affiliation:
Institut International de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements (iPHEP), UMR-CNRS 7262, Université de Poitiers UFR SFA, 40 avenue du Recteur Pineau, F-86022 Poitiers cedex, France
SYLVAIN ADNET
Affiliation:
Institut des Sciences de l'Evolution de Montpellier (ISE-M), UMR 5554 CNRS/UM/IRD/EPHE, CC064, Université de Montpellier, place Eugène Bataillon, F-34095 Montpellier cedex 05, France
LAURENT MARIVAUX
Affiliation:
Institut des Sciences de l'Evolution de Montpellier (ISE-M), UMR 5554 CNRS/UM/IRD/EPHE, CC064, Université de Montpellier, place Eugène Bataillon, F-34095 Montpellier cedex 05, France
JOHAN YANS
Affiliation:
Department of Geology, University of Namur, rue de Bruxelles 61, 5000 Namur, Belgium
CORENTIN NOIRET
Affiliation:
Department of Geology, University of Namur, rue de Bruxelles 61, 5000 Namur, Belgium
RODOLPHE TABUCE
Affiliation:
Institut des Sciences de l'Evolution de Montpellier (ISE-M), UMR 5554 CNRS/UM/IRD/EPHE, CC064, Université de Montpellier, place Eugène Bataillon, F-34095 Montpellier cedex 05, France
JÉRÔME SURAULT
Affiliation:
Institut International de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements (iPHEP), UMR-CNRS 7262, Université de Poitiers UFR SFA, 40 avenue du Recteur Pineau, F-86022 Poitiers cedex, France
IMAD EL KATI
Affiliation:
Laboratoire de Géologie, Géophysique, Géorisques et Environnement (3GE), Département de Géologie, Université Ibn Tofail, Faculté des Sciences, BP. 133, Kenitra, Morocco
SÉBASTIEN ENAULT
Affiliation:
Institut des Sciences de l'Evolution de Montpellier (ISE-M), UMR 5554 CNRS/UM/IRD/EPHE, CC064, Université de Montpellier, place Eugène Bataillon, F-34095 Montpellier cedex 05, France
LAHSSEN BAIDDER
Affiliation:
Laboratoire Géosciences, Université Hassan II-Casablanca, BP 5366 Maârif, Casablanca, Morocco
OMAR SADDIQI
Affiliation:
Laboratoire Géosciences, Université Hassan II-Casablanca, BP 5366 Maârif, Casablanca, Morocco
MOHAMED BENAMMI
Affiliation:
Laboratoire de Géologie, Géophysique, Géorisques et Environnement (3GE), Département de Géologie, Université Ibn Tofail, Faculté des Sciences, BP. 133, Kenitra, Morocco
*
Author for correspondence: [email protected]

Abstract

New Palaeogene vertebrate localities were recently reported in the southern Dakhla area (southwestern Morocco). The Eocene sediment strata crops out on cliffs along the Atlantic Ocean coast. Vertebrate remains come from five conglomeratic sandstone beds and are principally represented by isolated teeth belonging to micromammals, selachians and bony fishes, a proboscidean assigned to ?Numidotherium sp. and many remains of archaeocete whales (Basilosauridae). From fieldwork five lithostratigraphic sections were described, essentially based on the lithological characteristic of sediments. Despite the lateral variations of facies, correlations between these five sections were possible on the basis of fossil-bearing beds (A1, B1, B2, C1 and C2) and five lithological units were identified. The lower part of the section consists of rhythmically bedded, chert-rich marine siltstones and marls with thin black phosphorite with organic matter at the base. The overlying units include coarse-grained to microconglomeratic sandstones interbedded with silts, indicating deposition in a shallow-marine environment with fluvial influence. The natural remanence magnetization of a total of 50 samples was measured; the intensity of most of the samples is too weak however, before or after the first step of demagnetization. The palaeomagnetic data from the samples are very unstable, except for eight from three similar sandstone levels which show a normal polarity. Matched with biostratigraphic data on rodents, primates, the selachian, sirenian and cetacean faunas, the new carbon isotope chemostratigraphy on organics (1) refines the age of the uppermost C2 fossil-bearing bed to earliest Oligocene time and (2) confirms the Priabonian age of the B1 to C1 levels.

Type
Review Article
Copyright
Copyright © Cambridge University Press 2017 

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