The last 1 million years of the extinct genus Discoaster; Plio-Pleistocene environment and productivity at Site U1476 (Mozambique Channel)

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doi: 10.1016/j.palaeo.2018.05.043
Author(s): Tangunan, Deborah N.; Baumann, Karl-Heinz; Just, Janna; LeVay, Leah J.; Barker, Stephen; Brentegani, Luna; De Vleeschouwer, David; Hall, Ian R.; Hemming, Sidney; Norris, Richard
International Ocean Discovery Program, Expedition 361 Scientists
Author Affiliation(s): Primary:
University of Bremen, MARUM, Bremen, Germany
Other:
Texas A&M University, United States
Cardiff University, United Kingdom
University of Technology Queensland Gardens, Australia
Columbia University, United States
Scripps Institution of Oceanography, United States
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Vol.505, p.187-197. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Includes appendices. 86 refs.; illus., incl. 1 table, sketch map
Summary: A detailed paleoenvironment reconstruction from the Mozambique Channel, western Indian Ocean, based on the calcareous nannoplankton assemblages was conducted for the interval between 2.85 and 1.85 Myr. This study covers the period during which the successive extinction of the last five species of discoasters occurred. New productivity data obtained from the abundances of the Discoaster species (Discoaster brouweri, D. triradiatus, D. pentaradiatus, D. surculus, and D. tamalis) and other indicative calcareous nannoplankton taxa showed abundance variations, which were at paced with the 100, 41, and 23 kyr astronomical periodicities. A shift in the productivity and water-column stratification proxies occurred at ∼2.4 Ma, after the onset of the Northern Hemisphere glaciation. Here we propose that the variability recorded at International Ocean Discovery Program Site U1476 reflects the interplay between forcing associated with warm tropical Pacific and cold southern ocean influences. The former is shown by consistent occurrence of warm water taxa (Calcidiscus leptoporus, Oolithotus spp., Rhabdosphaera clavigera, Syracosphaera spp., Umbellosphaera spp.), typical of Indonesian Throughflow surface waters. On the other hand, the occurrence of Coccolithus pelagicus indicates the influence of cold, nutrient-rich sub-Antarctic surface waters. A more mixed water column initiated at ∼2.4 Ma, and a consequent productivity increase led to the gradual reduction of the Discoaster species, until their extinction at 1.91 Ma. This period was characterized by the low values of the Florisphaera profunda index and high abundances of upper photic zone flora, indicative of nutrient-rich surface water conditions. High productivity at the location during this period could have also been amplified by localized upwelling events driven by the Mozambique Channel eddies.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 08 Paleontology, General; 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Calcareous composition; Cenozoic; Discoaster; Discoasteridae; Expedition 361; Extinct taxa; IODP Site U1476; Indian Ocean; International Ocean Discovery Program; Microfossils; Models; Mozambique Channel; Nannofossils; Nannoplankton; Neogene; Paleoecology; Paleoenvironment; Paleotemperature; Plankton; Pleistocene; Pliocene; Preservation; Quaternary; Reconstruction; Tertiary
Coordinates: S154916 S154915 E0414608 E0414608
Record ID: 2018093465
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands