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Nouvelles données sur les Charophytes et Ostracodes du Jurassique moyen-supérieur - Crétacé inférieur de l'Atlas marocain [New data on the Middle-Upper Jurassic - Lower Cretaceous Charophytes and Ostracods from the Moroccan Atlas]

Author(s): Mojon Pierre-Olivier | Haddoumi Hamid | Charrière André

Journal: Carnets de Géologie
ISSN 1765-2553

Volume: CG2009;
Issue: M03;
Start page: 1;
Date: 2009;
Original page

Keywords: Charophytes | Ostracods | Middle-Upper Jurassic | Lower Cretaceous | Atlas Mountains | Morocco

The Middle Jurassic-Lower Cretaceous continental "Red Beds" of the Moroccan Atlas have provided very interesting new taxa of charophytes and lacustrine ostracods: Aclistochara africana n.sp. (Bathonian), Feistiella atlantis n.sp. (Hauterivian-Lower Barremian), Cypridea suprajurassica n.sp., Cypridea mohandi n.sp. and Cypridea demnatensis n.sp. (Oxfordian ? - Kimmeridgian), Harbinia atlasica n.sp. (Hauterivian ? - Lower Barremian). Micropaleontological data obtained after 2002 contributed the following: * In the central High-Atlas, discovery of Upper Jurassic charophytes and freshwater ostracods (Dictyoclavator ramalhoi, Porochara kimmeridgensis, Aclistochara bransoni, Cypridea suprajurassica, Cypridea mohandi, Cypridea demnatensis) evince a Barremian ingression, its restricted marine character attested by lagoonal-brackish water ostracods (Harbinia atlasica) and presumed marine ostracods Trachyleberididae (cf. Strigosocythere strigosa, Cythereis ? sp., Protocythere ? sp.) associated with well-developed gypsiferous evaporites. * In the eastern High-Atlas, charophytes have been found at levels related to the Jurassic/Cretaceous boundary (Upper Tithonian–Berriasian Porochara maxima). * In the non-marine Lower Cretaceous (Hauterivian ? - Barremian) of the central High-Atlas, mixed Eurasian e and Gondwanian g assemblages of charophytes: Globator (e) and Feistiella (g), and brackish-lacustrine ostracods: (Fabanella-Cetacella (e), Darwinula-Cypridea-Harbinia (e & g) and Salvadoriella-Petrobrasia-Reconcavona-Paracypridea (g), were discovered. * Complementary data for the Lower Cretaceous charophyte biozonation (Upper Valanginian-Lower Barremian interval) with Globator hemiglobatoroides Mojon n.sp. (Cenozone M7a, NE-Spain) and Globator mutabilis (Cenozone M7b) from NE-Spain and Morocco (central High-Atlas) were obtained. * In the Moroccan Atlas area several stages in the breaking up of Pangea and the opening of the Atlantic Ocean have been recognized. These dislocations took place mainly during Bathonian times but also involved portions of the Kimmeridgian and Barremian.

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