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Journal of Micropalaeontology An open-access journal of The Micropalaeontological Society
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Volume 9, issue 2
J. Micropalaeontol., 9, 145–151, 1991
https://doi.org/10.1144/jm.9.2.145
© Author(s) 1991. This work is distributed under
the Creative Commons Attribution 4.0 License.
J. Micropalaeontol., 9, 145–151, 1991
https://doi.org/10.1144/jm.9.2.145
© Author(s) 1991. This work is distributed under
the Creative Commons Attribution 4.0 License.

  01 Mar 1991

01 Mar 1991

Late Miocene-Early Pliocene Planktonic Foraminifera and Palaeoceanography of the North Atlantic

Peter W. P. Hooper1, Brian M. Funnell2, and Philip P. E. Weaver3 Peter W. P. Hooper et al.
  • 18 Edward Avenue, Bishopstoke, Eastleigh, Hants SO5 6EG
  • 2School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ
  • 3Institute of Oceanographic Sciences Deacon Laboratory, Brook Road, Wormley, Godalming, Surrey GU8 5UB

Abstract. Relative abundance variations of planktonic Foraminifera have been studied for the Late Miocene to Early Pliocene time interval of 7.0 to 3.5 Ma from three sites in the North East Atlantic; DSDP607 (41°N), DSDP609 (50°N) and DSDP611 (53°N), Particular attention has been given to the percentage of benthic Foraminifera of total (benthic + planktonic) Foraminifera as an index of dissolution by aggressive bottom waters, and to the percentage of dextral Neogloboquadrina pachyderma of total (dextral + sinistral) N. pachyderma as an index of “Sub-Polar” or warmer waters.

Strong dissolution, probably associated with the northward penetration of aggressive Antarctic Bottom Water, is observed at two of the sites up to and during the initiation of the Messinian “Salinity Crisis” in the adjoining Mediterranean Sea at about 5.8 Ma. All three sites exhibit strong cyclic fluctuations of the percentage of dextral N. pachyderma during the Messinian “Salinity Crisis” interval, from approximately 5.8 Ma to 4.8 Ma. These are interpreted as indicating wide-ranging oscillations of a water mass boundary, analogous to the present-day Polar Front, in the North Atlantic during the “Salinity Crisis”. Following the re-filling of the Mediterranean with normal marine waters at about 4.8 Ma, the dextral form of N. pachyderma, which is more characteristic of warmer waters than the sinistral form, becomes the dominant form and shows less quantitative variation at all three sites throughout the Early Pliocene.

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