A new Late Miocene to Pleistocene palynomorph zonation for the western offshore Niger Delta

Adeonipekun, Peter Adegbenga; Sowunmi, M.A.; Richards, Keith

doi:10.1080/01916122.2015.1107652

Cited by 16 publications

(18 citation statements)

References 10 publications

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“…The occurrence of montane bisaccate pollen -Podocarpus milanjianus -in the Niger Delta basin from around 2.7 Ma has been reported (Knapp 1971, Sowunmi 1987, Adeonipekun et al 2015. This supports the invigoration of the NE trade winds at this time.…”

mentioning

confidence: 54%

“…1). Details of these vegetation types and subtypes are given in Keay (1959), Sowunmi (1995) and Adeonipekun et al (2015).…”

Section: Niger Delta Vegetationmentioning

confidence: 99%

“…It is curious, however, that the Niger Delta, situated within the Congo-Guinean lowland rain forest block since at least the early Tertiary (Germeraad et al 1968, Evamy et al 1978, Sowunmi 1986, would have its palaeovegetation strictly dominated by savanna pollen. In contrast, all published Tertiary, Quaternary and Holocene studies of the offshore Niger Delta have reported low content of typical savanna pollen (Sowunmi 1981a, Adeonipekun et al 2015. The assumption that all Poaceae pollen is from inland savanna, which has informed the inference of domination by dry palaeoclimate, is therefore questionable, because coastal savanna contributed more than 50% of this Poaceae pollen (Adeonipekun & Olowokudejo 2013).…”

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confidence: 99%

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Palaeoclimatology and biostratigraphic significance of late Neogene/Quaternary vegetational changes recorded in the offshore western Niger Delta

Adeonipekun

Sowunmi

2019

Acta Palaeobotanica

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Attempts at reconstructing palaeoclimatic changes over time using palynomorphs of three oil wells drilled in the shallow offshore Niger Delta led to cluster analysis-aided recognition of seven pollen zones. These pollen zones are equivalent to ten palaeoclimatic zones with alternating dry and wet conditions. The palynomorphs were classified into phytoecological groups and changes in their relative abundances were employed to interpret the palaeoclimatic conditions of their source areas. Contrasting fluctuations in the proportions of the Spore (Pteridophytes) phytoecological group and those of the Poaceae were the main basis for palaeoclimatic inferences. Trends of the occurrence of other phytoecological groups were used to substantiate our palaeoclimatic inferences. In the latest Miocene (5.8–5.5 Ma), climatic conditions were mainly wet until between 5.5 and 5.0 Ma, when extreme dry conditions prevailed. The early Pliocene part (5.0–>3.4 Ma) was generally wet, while the late Pliocene part (<3.0–2.7 Ma) was extremely dry, with wet conditions re-occurring at the latest Pliocene/earliest Pleistocene boundary at a lower magnitude than those of the early Pliocene. This is inferred from the bloom of open vegetation Acanthaceae undif., Polygala sp. and Asystacia gangetica, along with montane Podocarpus milanjianus from 2.4 Ma through 2.0 Ma and younger. The Acanthaceae bloom recorded the evolution of A. gangetica in the latest Pliocene/earliest Pleistocene at around 2.0 Ma in the Niger Delta. The upper Early Pliocene regional wet event is associated with distinct peaks of riverine forest, freshwater swamp and mangrove pollen. Our results further support earlier findings from other parts of West Africa with respect to palaeoclimatic changes in the late Neogene/earliest Quaternary. Equivalent qualitative palynostratigraphic events were recognized within the pollen zones which are useful for age determination, and the significance of biostratigraphic correlation of the zones is stressed.

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confidence: 54%

“…1). Details of these vegetation types and subtypes are given in Keay (1959), Sowunmi (1995) and Adeonipekun et al (2015).…”

Section: Niger Delta Vegetationmentioning

confidence: 99%

mentioning

confidence: 99%

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Palaeoclimatology and biostratigraphic significance of late Neogene/Quaternary vegetational changes recorded in the offshore western Niger Delta

Adeonipekun

Sowunmi

2019

Acta Palaeobotanica

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“…It is important to note that one single occurrence of a typical savanna pollen was found in one of the treated samples and hence makes up the Savanna group for its significance at that level. Sowunmi (1981a), Adeonipekun (2006) and Adeonipekun et al (2015) reported low occurrences of typical savanna pollen from the Late Quaternary and Late Tertiary sediments respectively of the Niger delta relative to the rainforest and even airborne montane Podocarpus milanjianus pollen. This indicates that the Poaceae recorded are mainly those from coastal savanna (Adeonipekun 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Using the recovered pollen and spores, eight phytoecological groups were made on the basis of the known present day natural distribution of their parent plant sources. The works of Hutchinson & Dalziel (1954, 1958, 1963, 1968, 1972, Keay (1959), Sowunmi (1973Sowunmi ( , 1995Sowunmi ( , 1981aSowunmi ( , 1981b, Adeonipekun (2006) and Adeonipekun et al (2015) guided the grouping. For the sedimentological analysis, sub-samples were gently crushed and washed with water until they became clean and dried for microscopic analysis through visual examination using the American/Canadian stratigraphic code.…”

Section: Methodsmentioning

confidence: 99%

The Late Quaternary vegetational and environmental history of western tropical Africa: the eastern Benin Basin, Lagos, Nigeria

Adeonipekun

Adeniyi

Mateawo³

et al. 2017

geol

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A palynological study of a 30 m borehole within the Akoka campus of the University of Lagos, Akoka, Nigeria revealed Late Quaternary paleo-vegetational, climatic and environmental changes. Sixteen samples at a regular interval of 2 m were subjected to standard palynological and sedimentological techniques. Six pollen zones representing six paleoclimatic phases within the Late Quaternary period were recognized. The age model is based on two radiocarbon dates (6 m: 5,495 ± 25 14 C yr and 12 m: 15,660 ± 40 14 C yr) and, by extrapolation, the sequence spans approximately the last 35,000 yr BP. The African maximum transgression and the African Humid Period (wet paleoclimate maximum) -the Nouaktchottian, and Pre-Nouaktchottian respectively -were recognized, while the Ogolian II (Erg II) was stratigraphically recognized and the Upper Inchirian extrapolated. Recovered diatom frustules with other proxies were employed for paleoclimatic and paleoecological deductions. Four hydrological cycles and three paleoecological settings were identified. Results from this work indicate the co-eval record of paleoclimatic events across Africa, suspected cooling during the African maximum transgression in Nigeria and the usefulness of coastal freshwater swamp sediments for paleoclimate studies.

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Following the Mangroves: diversification in the banded lampeye Aplocheilichthys spilauchen (Duméril, 1861) (Cyprinodontiformes: Procatopodidae) along the Atlantic coast of Africa

et al. 2021

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Available ecological information, an extensive distributional range, conflicting osteological data, and a proposed early Miocene origin provide the impetus for the present study which investigates genetic structuring, biogeographic, and phylogenetic relationships within the Aplocheilichthys spilauchen lineage. Through the analysis of the mitochondrial gene COI, species delimitation methods (ABGD, GB, GMYC, bPTP) were applied, recognizing 6-7 OTUs with absolute pairwise genetic distances ranging between 8 and 22%. The onset of diversification is estimated to be within the middle Miocene and both dispersal and vicariance-shaped A. spilauchen diversity and distribution, as suggested by time-calibrated and ancestral range reconstruction (S-DIVA) analyses. We report for the first time, a pattern of diversification within a lineage of brackish water fish that is concordant with the historical distribution of coastal mangroves forests, shaped by a series of historical events that likely affected forest cover since the middle Miocene (e.g. major climate shifts and sealevel fluctuations, onset of the modern Congo River outlet, increased volcanism in the Cameroon Volcanic Line).

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A new Late Miocene to Pleistocene palynomorph zonation for the western offshore Niger Delta

Cited by 16 publications

References 10 publications

Palaeoclimatology and biostratigraphic significance of late Neogene/Quaternary vegetational changes recorded in the offshore western Niger Delta

Palaeoclimatology and biostratigraphic significance of late Neogene/Quaternary vegetational changes recorded in the offshore western Niger Delta

The Late Quaternary vegetational and environmental history of western tropical Africa: the eastern Benin Basin, Lagos, Nigeria

Following the Mangroves: diversification in the banded lampeye Aplocheilichthys spilauchen (Duméril, 1861) (Cyprinodontiformes: Procatopodidae) along the Atlantic coast of Africa

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