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  • 1
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    Mass estimates and morphometric meassurements of Discoaster species and Sphenolithus from Ceara Rise ODP Site 927 (2012)
    PANGAEA
    In:  Supplement to: Preiß-Daimler, Inga; Baumann, Karl-Heinz; Henrich, Rüdiger (2012): Carbonate budget mass estimates for Neogene discoasters from the Equatorial Atlantic (Ceara Rise: ODP Site 927). Journal of Micropalaeontology, 31(2), 169-178, https://doi.org/10.1144/0262-821X11-014
    Details
    Publication Date: 2023-07-10
    Description: Mass estimates for Late Miocene and Pliocene (8.6-3.25 Ma) Discoaster species and Sphenolithus are determined using samples of the equatorial Atlantic (Ceara Rise: ODP Site 927). Based on morphometric measurements, 3D computer models were created for 11 Discoaster species and their volumes calculated. From these, shape factors (ks) were derived to allow calculation of mass for different-sized discoasters and Sphenolithus abies. The mass estimates were then used to calculate the contribution of nannofossils to the total nannofossil carbonate. The discoaster contribution ranges from 10% to 40%, with a decreasing trend through the investigated interval. However, our estimates of total nannofossil carbonate from size-corrected abundance data are consistently 30-50% lower than estimates from grain-size measurement; this suggests that data based on mass estimates need to be interpreted with caution.
    Keywords: 154-927; Area in square milimeter; Center for Marine Environmental Sciences; COMPCORE; Composite Core; Half ray width; Image analysis; Joides Resolution; Leg154; MARUM; Radius; Ray length; Ray tip base; South Atlantic Ocean; Species
    Type: Dataset
    Format: text/tab-separated-values, 2482 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Sediment transport and turbidite architecture in the submarine Dakar Canyon off Senegal, NW-Africa (2011)
    Elsevier
    In:  Journal of African Earth Sciences, 60 (3). pp. 196-208.
    Details
    Publication Date: 2019-09-23
    Description: The submarine Dakar Canyon incises the continental margin at the transition of the hyperarid Sahara to the semiarid Sahel Zone, and acts as an effective pathway for gravity-driven sediment transport. Four gravity cores recovered directly from the canyon axis were investigated in order to reconstruct the sedimentation processes in the Dakar Canyon during the Late Quaternary. In addition, a hemipelagic record from the northern levee of the canyon was analysed for monitoring background sediment supply, which is dominated by dust input in the area. Coarse terrigenous silt size data and high Ti/Ca ratios reflect overall increased higher dust supply during the last two peak glacials. During these times wide-extensive sand sea covered the exposed shelf almost completely. However, in interglacial periods wind stress diminished considerably and only minor amounts of dust were supplied to the outer shelf and continental slope. Two major periods of turbidite depositions are recorded in intervals from final glacial sea level lowstands to early deglacial sea level rise of the last two glacial/interglacial cycles (i.e. between 141 and 131 kyr BP and from 23.2 to 14.2 kyr BP). These turbidite deposits consist of sandy to silty sediments. Detailed grain size analyses were used to reconstruct the sedimentary characteristics and flow processes of these turbidity currents. A much higher frequency in turbidite activity occur around 135 kyr BP in contrast to the second interval around 18 kyr BP, suggesting a higher sediment budget in the source area. Based on the sedimentological investigation of the turbidites we provide a schematic model for the sedimentation processes in the Dakar Canyon.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.jafrearsci.2011.02.010
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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