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Vegetation Dynamics vs. Sediment Supply During the Late Quaternary: Paradigm of Sea Level Change and Two Distinct Time-Bound Stages of the Niger Delta Coastal Evolution
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  • Onema Adojoh,
  • Fabienne Marret,
  • Robert Duller,
  • Peter Osterloff,
  • Beverly Osalor
Onema Adojoh
Case Western Reserve University, Ohio, Case Western Reserve University, Ohio

Corresponding Author:[email protected]

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Fabienne Marret
University of Liverpool, UK, University of Liverpool, UK
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Robert Duller
University of Liverpool, UK, University of Liverpool, UK
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Peter Osterloff
Shell Petroleum Development Company, London, Shell Petroleum Development Company, London
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Beverly Osalor
Case Western Reserve University, Ohio, Case Western Reserve University, Ohio
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Abstract

This paper examines the impact of climate-sea level controls on the vegetation and evolution of the Niger Delta during the Late Quaternary. The extraneous controls on the environment outlined in this context confirm a direct link between vegetation dynamics (pollen data), sediment supply, and the landscape evolution of the Niger Delta between 20 ka and 6.5 ka. Two phases of sedimentation are recognized based on multiple proxies analyzed in three gravity cores obtained from the shallow offshore at ~40 m water depth. Phase I records abundant occurrences of Poaceae, Cyperaceae, and Podocarpus pollen from a dry hinterland, charred grass cuticles, nonmarine alga Pediastrum, high Ti/Zr ratio, and lower sedimentation from 20-11.7 ka. Phase II records an expansion of mangrove vegetation, high Fe/S ratio, and increase in planktonic foraminifera between 11.7 ka and 6.5 ka. This second phase is attributed to sea-level rise and higher sedimentation during the development of delta plain and mangrove vegetation on the gently sloping shelf. These sequential records provide a new clue about the link between the evolutionary stages of the Niger Delta landscape and vegetation dynamics during two distinct time-bound intervals, which potentially delineate the boundary between two Marine Isotope Stages: MIS2 (late glacial period) and MIS1 (interglacial period).