TITLE:
Shallow Marine Cretaceous Sequences and Petroleum Geology of the Onshore Portion Rio del Rey Basin, Cameroon, Gulf of Guinea
AUTHORS:
Olivier Anoh Njoh, Agbor Junior Taku
KEYWORDS:
Cretaceous, Depositional Environment, Lithofacies, Petroleum System, Rio del Rey
JOURNAL NAME:
Open Journal of Marine Science,
Vol.6 No.2,
February
22,
2016
ABSTRACT: Extensive thickly folded
sedimentary sequences are exposed onshore of theRio del ReyBasin contrary to previous reports of
their rarity. Shales predominate, frequently intercalated by marlstones,
sandstones, mudstones, limestones and marls and have been intruded in places by
volcanic rocks of the Cameroon Volcanic Line (CVL). An integration of
lithostratigraphic, paleontologic, granulometric and petrographic data
generated from field and laboratory studies, permitted the identification of
eleven (11) lithofacies which were subsequently grouped into three facies
associations to facilitate the reconstruction of the paleo-depositional
environment. Graphic logs constructed from the different outcrops studied
revealed general coarsening upward sequences. Mega body fossils recovered from
these sediments include severely altered, ferruginized fish and turtle-like
heads, bivalve shells and moulds. Two bivalve taxa were identified:Exogyra ponderosa(Roemer) and members of theVenericardiinaesub-family. Textural and mineralogical
details were obtained from granulometric and thin sections (microscopy).
Interpretation of these data inferred an open relatively deeper marine,
probably middle neritic to near shore transitionalintertidal environments into which
these sediments previously dated as Lower to Upper Cretaceouswere deposited. Elements of a possible
petroleum system: source and reservoir rocks, migratory pathways and trapping
conditions, have been pointed out and thought to exist in space and time.