Neogene and Quaternary calcareous nannofossils from the Blake Ridge, sites 994, 995, and 997

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doi: 10.2973/odp.proc.sr.164.232.2000
Author(s): Okada, Hisatake
Ocean Drilling Program, Leg 164, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
Hokkaido University, Department of Earth and Planetary Sciences, Sapporo, Japan
Other:
University of Tokyo, Japan
Ocean Drilling Program, United States
U. S. Geological Survey, United States
University of Texas at Arlington, United States
University of Michigan, United States
Agder College, Norway
University of Bristol, United Kingdom
McGill University, Canada
Osaka Kyoiku University, Japan
Woods Hole Oceanographic Institution, United States
Lamont-Doherty Earth Observatory, United States
Osservatorio Geofisico-Sperimentale, Italy
La Trobe University, Australia
GEOMAR, Federal Republic of Germany
Hokkaido University, Japan
Université Pierre et Marie Curie, France
Georgia Institute of Technology, United States
Geological Survey of Japan, Japan
CREGU BP 23, France
Federal Institute for Geosciences, Federal Republic of Germany
Naval Research Laboratory, United States
Volume Title: Proceedings of the Ocean Drilling Program; volume 164; scientific results; gas hydrate sampling on the Blake Ridge and Carolina Rise; covering Leg 164 of the cruises of the drilling vessel JOIDES Resolution, Halifax, Nova Scotia, to Miami, Florida, sites 991-997, 31 October-19 December 1995
Volume Author(s): Paull, Charles K.; Matsumoto, Ryo; Wallace, Paul J.; Black, Nancy R.; Borowski, Walter S.; Collett, Timothy S.; Damuth, John E.; Dickens, Gerald R.; Egeberg, Per Kristian; Goodman, Kim; Hesse, Reinhard F.; Hiroki, Yoshihisa; Holbrook, W. Steven; Hoskins, Hartley; Ladd, John; Lodolo, Emanuele; Lorenson, Thomas D.; Musgrave, Robert J.; Naehr, Thomas H.; Okada, Hisatake; Pierre, Catherine; Ruppel, Carolyn D.; Satoh, Mikio; Thiéry, Régis; Watanabe, Yoshio; Wehner, Hermann; Winters, William J.; Wood, Warren T.; Miller, Christine M.; Reigel, Ruth
Source: Proceedings of the Ocean Drilling Program; volume 164; scientific results; gas hydrate sampling on the Blake Ridge and Carolina Rise; covering Leg 164 of the cruises of the drilling vessel JOIDES Resolution, Halifax, Nova Scotia, to Miami, Florida, sites 991-997, 31 October-19 December 1995, Charles K. Paull, Ryo Matsumoto, Paul J. Wallace, Nancy R. Black, Walter S. Borowski, Timothy S. Collett, John E. Damuth, Gerald R. Dickens, Per Kristian Egeberg, Kim Goodman, Reinhard F. Hesse, Yoshihisa Hiroki, W. Steven Holbrook, Hartley Hoskins, John Ladd, Emanuele Lodolo, Thomas D. Lorenson, Robert J. Musgrave, Thomas H. Naehr, Hisatake Okada, Catherine Pierre, Carolyn D. Ruppel, Mikio Satoh, Régis Thiéry, Yoshio Watanabe, Hermann Wehner, William J. Winters, Warren T. Wood, Christine M. Miller and Ruth Reigel; Ocean Drilling Program, Leg 164, Shipboard Scientific Party, College Station, TX. Proceedings of the Ocean Drilling Program, Scientific Results, Vol.164, p.331-341. Publisher: Texas A & M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0884-5891
Note: In English. 36 refs.; illus., incl. geol. sketch map, 1 table, strat. col.
Summary: Twenty routinely used nannofossil datums in the late Neogene and Quaternary were identified at three Blake Ridge sites drilled during Leg 164. The quantitative investigation of the nannofossil assemblages in 236 samples selected from Hole 994C provide new biostratigraphic and paleoceanographic information. Although mostly overlooked previously, Umbilicosphaera aequiscutum is an abundant component of the late Neogene flora, and its last occurrence at ∼2.3 Ma is a useful new biostratigraphic event. Small Gephyrocapsa evolved within the upper part of Subzone CN11a (∼4.3 Ma), and after an initial acme, it temporarily disappeared for 400 k.y., between 2.9 and 2.5 Ma. Medium-sized Gephyrocapsa evolved in the latest Pliocene ∼2.2 Ma), and after two short temporary disappearances, common specimens occurred continuously just above the Pliocene/Pleistocene boundary. The base of Subzone CN13b should be recognized as the beginning of the continuous occurrence of medium-sized (>4 µm) Gephyrocapsa. Stratigraphic variation in abundance of the very small placoliths and Florisphaera profunda alternated, indicating potential of the former as a proxy for the paleoproductivity. At this site, it is likely that upwelling took place during three time periods in the late Neogene (6.0-4.6 Ma, 2.3-2.1 Ma, and 2.0-1.8 Ma) and also in the early Pleistocene (1.4-0.9 Ma). Weak upwelling is also likely to have occurred intermittently through the late Pliocene. Due to the sharp and abrupt turnover of the nannofossils, which resulted from an evolution of very competitive species, the paleoproductivity of the late Pleistocene is not clear. The site was mostly in an oligotrophic central gyre setting during the 4.6- to 2.3-Ma interval, intermittently between 2.1 and 1.4 Ma, and continuously for the last several tens of thousand years.
Year of Publication: 2000
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Assemblages; Atlantic Ocean; Biostratigraphy; Blake-Bahama Outer Ridge; Cenozoic; Cores; Depositional environment; Leg 164; Marine sediments; Microfossils; Nannofossils; Neogene; North Atlantic; ODP Site 994; ODP Site 995; ODP Site 997; Ocean Drilling Program; Plantae; Pleistocene; Pliocene; Quaternary; Sedimentation; Sedimentation rates; Sediments; Tertiary
Coordinates: N315035 N315035 W0752807 W0752807
N314812 N314812 W0753118 W0753118
N314708 N314708 W0753245 W0753245
Record ID: 2001025828
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