Shell size variation of the planktonic foraminifer Neogloboquadrina pachyderma sin. in the Norwegian-Greenland Sea during the last 1.3 Myrs; implications for paleoceanographic reconstructions

Author(s): Huber, Robert; Meggers, Helge; Baumann, Karl-Heinz; Raymo, Maureen E.; Henrich, Rüdiger
Author Affiliation(s): Primary:
University of Bremen, Department of Geosciences, Bremen, Federal Republic of Germany
Other:
Massachusetts Institute of Technology, Cambridge, MA, United States
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 160(3-4), p.193-212. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. Includes appendix. 58 refs.; illus., incl. 3 tables, sketch map
Summary: We present measurements of the maximum diameter of the planktonic foraminifer Neogloboquadrina pachyderma sin. from six sediment cores (Ocean Drilling Program sites 643, 644, 907, 909, 985 and 987) from the Norwegian-Greenland Sea. Our data show a distinct net increase in mean shell size of N. pachyderma sin. at all sites during the last 1.3 Ma, with largest shell sizes reached after 0.4 Ma. External factors such as glacial-interglacial variability and carbonate dissolution alone cannot account for the observed variation in mean shell size of N. pachyderma sin. We consider the observed shell size increase to mirror an evolutionary trend towards better adaptation of N. pachyderma sin. to the cold water environment after 1.1-1.0 Ma. Probably, the Mid Pleistocene climate shift and the associated change of amplitude and frequency of glacial-interglacial fluctuations have triggered the evolution of this planktonic foraminifer. Oxygen and carbon stable isotope analyses of different shell size classes indicate that the observed shell size increase could not be explained by the functional concept that larger shells promote increasing sinking velocities during gametogenesis. For paleoceanographic reconstructions, the evolutionary adaptation of Neogloboquadrina pachyderma sin. to the cold water habitat has significant implications. Carbonate sedimentation in highest latitudes is highly dependent on the presence of this species. In the Norwegian-Greenland Sea, carbonate-poor intervals before 1.1 Ma are, therefore, not necessarily related to severe glacial conditions. They are probably attributed to the absence of this not yet polar-adapted species. Further, transfer function and modern analog techniques used for the reconstruction of surface water conditions in high latitudes could, therefore, contain a large range of errors if they were applied to samples older than 1.1-1.0 Myrs. Abstract Copyright (2000) Elsevier, B.V.
Year of Publication: 2000
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Adaptation; Arctic Ocean; Biochemistry; Biologic evolution; C-13/C-12; Carbon; Carbonate sediments; Cenozoic; Climate change; Cores; Foraminifera; Geochemistry; Glacial environment; Glaciomarine environment; Globigerinacea; Interglacial environment; Invertebrata; Isotope ratios; Isotopes; Leg 104; Leg 151; Leg 162; Marine environment; Marine sediments; Microfossils; Morphology; Neogloboquadrina; Neogloboquadrina pachyderma; Norwegian Sea; O-18/O-16; ODP Site 643; ODP Site 644; ODP Site 907; ODP Site 909; ODP Site 985; ODP Site 987; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleoclimatology; Paleoecology; Paleotemperature; Planktonic taxa; Pleistocene; Protista; Quaternary; Rotaliina; Sediments; Shells; Size; Stable isotopes; Statistical analysis
Coordinates: N664042 N664042 E0043436 E0043436
N674254 N674254 E0010200 E0010200
N665629 N665629 W0062700 W0062700
N691459 N691459 W0124154 W0124154
N702948 N702948 W0175614 W0175614
N783505 N783505 E0030416 E0030416
Record ID: 2000051587
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands