Associations de kystes de dinoflagellés des séries du Jurassique supérieur (Oxfordien–Tithonien) du Rif externe (Prérif interne et Mésorif,Maroc) et comparaisons régionales |
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Authors: | Touria Hssaida Soumia Chahidi Mohamed Benzaggagh James B Riding Fatima Oumalch |
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Institution: | 1. Faculté des sciences de Ben M''Sik, université Hassan II Mohammedia, avenue Cdt Driss El Harti, BP 7955, Ben M''Sik 20.800, Casablanca, Maroc;2. Faculté des sciences, université Moulay Ismail, BP 11.201, Jbabra, Zitoune, Meknès, Maroc;3. British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG, Royaume-Uni;4. Office national des hydrocarbures et des mines (ONHYM), 5, avenue Moulay Hassan, 10.000 Rabat, Maroc |
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Abstract: | A biostratigraphic study of dinoflagellate cysts of the Upper Jurassic series from the eastern External Rif Chain, has been achieved for the first time on four outcrop sections : the DM section (Douar Marticha), the TB section (the Tarhchenna “Sof”), the KSD section (the Kef Mallou “Sof”) and the Y section (Douar Lamriene) among which three sections (TB, KSD and Y) are well-dated by ammonites and calpionellids fauna. The DM and TB sections are complementary in terms of stratigraphy and correspond respectively to the upper part of the “Ferrysch” Formation, a thick shaly–silty and sandy sequence assigned to the Callovian-Oxfordian stages and to the El Gouzat limestones Formation (Kimmeridgian - Lower Tithonian age) and to the Tarhchenna marly limestones Formation (Upper Tithonian age) from the EL Gouzat area (Mesorif). The KSD and Y sections are also complementary and correspond to the Kimmeridgian-Lower Tithonian Msila limestones Formation and to the overlying marly limestones Massif Formation of Upper Tithonian age, outcropping in the Msila region (Internal Prerif). These four sections have shown many dinocysts rich levels, which had allowed characterizing the Middle? and Upper Oxfordian substages in the DM section. In the other sections, the dinoflagellate cyst assemblages are nearly similar to those of the Kimmeridgian–Tithonian of many sections from the Boreal, Sub-boreal and North tethyan realms, particularily from England, Russia and South-East France basin. The results of the present work confirm once again, the important value of dinoflagellate cysts, for age dating of ammonites-lacking Mesozoic sedimentary sequences and for biostratigraphic correlations. |
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Keywords: | Biostratigraphie Kystes de dinoflagellé s Jurassique supé rieur Pré rif interne Mé sorif Rif externe Maroc |
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