Wits Evolutionary Studies Institute (ESI)

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    Palynological dating and palaeoenvironments of the M1 well, Middle Miocene, Niger Delta, Nigeria
    (2017-07) Durugbo, Ernest Uzodimma; Olayiwola, Moshood Adegboyega
    The need to increase our knowledge of palaeo-flora is important in palaeoclimatic and palaeoenvironmental reconstruction of the Tertiary Niger Delta as to highlight possible changes in the depositional environments over time. Hence, palynological data from the M1well from the western Niger Delta region were employed in an attempt to reconstruct the Middle Miocene palaeoenvironment and palaeoclimate. The detailed palynological analysis revealed diverse and abundant palynomorph assemblages. This consisted of pollen species 60.14%, spores 25.86%, algae (Botyococcus braunii, Pediastrum sp., and Concentricytes circulus) 10.53%, miscellaneous palynomorphs (fungal elements, diatom frustules and charred Gramineae cuticle) 2.62%, dinoflagellate cysts 0.79% and acritarchs 0.06%. The well is dated Middle Miocene based on the common occurrences of diagnostic middle Miocene Niger Delta palynomorphs. Four informal palynofloral assemblage zones (MPAZ) I–IV were defined and correlated with major cycles of alternating dry and wet climatic conditions. Sediments within MPAZ I and MPAZ II were assumed to have been deposited during dominantly wet periods while MPAZ IV and III showed brief dry pulses coupled with periods of marine transgressions. The palaeoenvironment fluctuated between nearshore and marginal marine inferred from abundant records of land-derived palynomorphs and the spotty records of the dinoflagellate cysts Nematosphaeropsis labyrinthus, Nematosphaeropsis lemniscata and Impagidinium sp.
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    The stable isotope setting of Australopithecus sediba at Malapa, South Africa.
    (Academic of Science of South Africa (ASSAf), 2016-07) Holt, E.; Dirks, P.; PLaczek, C.; Berger, L.R.
    We report delta C-13 and delta O-18 results from carbonate-cemented cave sediments at Malapa in South Africa. The sediments were deposited during a short-period magnetic reversal at 1.977±0.003 Ma, immediately preceding deposition of Facies D sediments that contain the type fossils of Australopithecus sediba. Values of delta C-13 range between -5.65 and -2.09 with an average of -4.58±0.54% (Vienna Pee Dee Belemnite, VPDB) and values of delta O-18 range between -6.14 and -3.84 with an average of -4.93±0.44% (VPDB). Despite signs of diagenetic alteration from metastable aragonite to calcite, the Malapa isotope values are similar to those obtained in two previous studies in South Africa for the same relative time period. Broadly, the Malapa delta C-13 values provide constraints on the palaeovegetation at Malapa. Because of the complex nature of the carbonate cements and mixed mineralogy in the samples, our estimates of vegetation type (C4-dominant) must be regarded as preliminary only. However, the indication of a mainly C4 landscape is in contrast to the reported diet of A. sediba, and suggests a diverse environment involving both grassland and riparian woodland.