Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies

Gibbs, S. J. and Young, J. R. and Bralower, T. J. and Shackleton, N. J. (2005) Nannofossil evolutionary events in the mid-Pliocene: an assessment of the degree of synchrony in the extinctions of Reticulofenestra pseudoumbilicus and Sphenolithus abies. Palaeogeography, Palaeoclimatology, Palaeoecology, 217 (1-2). pp. 155-172. DOI 10.1016/j.palaeo.2004.11.005

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Abstract

The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent attrition’ of nannofossil species that resulted from changes in the distribution of trophic resources, and deep-water and surface-water current systems, likely associated with the initiation of Northern Hemisphere glaciation. The extinctions of Sphenolithus abies and Reticulofenestra pseudoumbilicus were analysed in detail at ODP Sites 659, 662, and 926 in the equatorial and subequatorial Atlantic. These taxa show significantly different patterns of duration and timing of decline based on high-resolution abundance records and calibration with oxygen isotope stratigraphy. The initiation of abundance decline between 3.71 and 3.67 Ma and the extinction of S. abies between 3.56 and 3.52 Ma are diachronous. This extinction may have been a response to the intensification of glacial intervals at this time. In contrast, the last occurrence of R. pseudoumbilicus at 3.81–3.82 Ma appears to be a valid example of biostratigraphic (although not necessarily biological) synchrony in the fossil record. Direct environmental forcing is not attributable for the extinction of R. pseudoumbilicus; however, indirect physical and/or biological environmental stress may explain the observed patterns.

Item Type:	Article
Uncontrolled Keywords:	2006 AREP IA52 2005 P
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title:	Palaeogeography, Palaeoclimatology, Palaeoecology
Volume:	217
Page Range:	pp. 155-172
Identification Number:	10.1016/j.palaeo.2004.11.005
Depositing User:	Sarah Humbert
Date Deposited:	03 May 2011 10:37
Last Modified:	23 Jul 2013 09:58
URI:	http://eprints.esc.cam.ac.uk/id/eprint/1653

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