Biostratigraphy of Cretaceous-Neogene sedimentary infill of the Mamfe basin, southwest Cameroon: Paleoclimate implication. (October 2021)

• Record Type: Journal Article
• Authors: Bilobé, Jeanne Armelle; Feist-Burkhardt, Susanne; Eyong, John Takem; Samankassou, Elias
• Is Part Of: Journal of African earth sciences. Volume 182(2021)
• Publication Date: 2021-10
• Subjects: Biostratigraphy -- Paleoclimate -- Depositional environment -- Mamfe Basin -- Cameroon; Akw Akwen -- AOM amorphous organic matter -- Bad Badi -- Bach Bachu Ntai -- Bak Bakebe -- Bkr Bakarem River -- Bes Bakiep waterfall -- Bkw Bakwele -- CVL Cameroon Volcanic Line -- Eko Ekok -- Etk Etoko -- Eym Eyoumodjock -- Fig figure -- Fm Formation -- GPS Global Positioning System -- HCl Hydrochloric acid -- HEC Hydroxyethilic cellulose -- HF Hydrofluoric acid -- HNO3 Nitric acid -- JH John Hault -- Mam Mamue River -- m meter -- Nch Nchemba -- NFE Nfaitok -- NFI Nfainchang -- NW-SE northwest-southwest -- Oky Okoyong -- OM organic matter -- Sa Satom -- Tob Tabot -- LAD last appearance datum -- WCARS West and Central African Rift System; Earth sciences -- Africa -- Periodicals; Earth sciences -- Middle East -- Periodicals; Geology -- Africa -- Periodicals; Geology -- Middle East -- Periodicals; Sciences de la terre -- Afrique -- Périodiques; Sciences de la terre -- Moyen-Orient -- Périodiques; Géologie -- Afrique -- Périodiques; Géologie -- Moyen-Orient -- Périodiques; Earth sciences; Geology; Africa; Middle East; Periodicals; Electronic journals; 556.05
• DOI: 10.1016/j.jafrearsci.2021.104279
• Languages: English
• ISSNs: 1464-343X

Abstract

Abstract: A palynological investigation of sixteen (16) outcrops from Mamfe Basin, southwest Cameroon, has been carried out using spores, pollen and organic matter components to establish the biostratigraphic framework of the basin and reconstruct the depositional and paleoclimatic conditions. The inferred climatic trend is based on the distribution pattern of the recovered species, mainly the vertical occurrence and disappearance, for the time window investigated. Particulate organic matter are represented mainly by gymnosperm pollen grain Classopollis spp. and opaque phytoclasts. Some fern spores such as Cicatricosisporites venustus, Verrucatosporites spp ., P olypodiisporites aff . specious, Deltoidospora spp., Laevigatosporites spp., Polypodiaceoisporites spp., and Foveotriletes ornatus occur in significant amounts. Angiosperm pollen, including Echitricolporites spinosus, Monoporopollenites annulatus, Pachydermites diederixi and Sabicea-type, are locally present . Araucariacites spp. and Afropollis jardinus are less abundant, depending on the stratigraphic level . The palynological assemblage suggests an age ranging from early Barremian to Cenomanian. Additionally, we identified a level dated as Miocene to Pleistocene in one of the sections. Hygrophilous flora such as pteridophyte ( Cyathidites spp.) and angiosperm ( Afropollis jardinus ) is less present compared to xerophytic flora ( Classopollis ) along the studied sections, indicating significant climatic variation. Variation in palynomorph assemblages led to define three significant settings of the paleoclimate: 1) humid conditions prior to Barremian coinciding with the opening of the Atlantic Ocean; 2) arid to semi-arid conditions intermittent with short-lived humid phases from the Barremian to the Cenomanian; 3) humid conditions from the Miocene onwards. Thus, the palynological assemblage allows constraining the age of the basin infill and accessing the paleoclimatic states in the hinterland in Mamfe Basin, where powerful climate proxies are currently very limited. The basin appears to record regional rather than local climate fluctuations. Highlights: Mesozoic and Cenozoic paleoclimate conditions reconstructed using palynomorphs. Conditions humid and dry during Mesozoic and humid during Cenozoic. Opaque and translucent phytoclasts suggest the proximity to a terrestrial source. Intermittent freshwater influx recorded in the Nfaitok Formation. Terrestrial derived palynomorphs are the main components in the intervals studied.