Preliminary Results from Hole 704A: Arctic-Antarctic Correlation through Nannofossil Biochronology

Gard, Gunilla; Crux, Jason

doi:10.2973/odp.proc.sr.114.134.1991

Cited by 8 publications

(9 citation statements)

References 17 publications

(29 reference statements)

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“…Figure 31 compares the polarity chronozones and diatom zones assigned by previous workers. Hailwood & Clement (1991b), Ciesielski et al (1988 and Ciesielski (1991) with the assignments in this study. In addition, this figure illustrates the stratigraphical ranges of diatoms and calcareous nannofossils.…”

Section: Hole 697bsupporting

confidence: 72%

“…In addition, this figure illustrates the stratigraphical ranges of diatoms and calcareous nannofossils. The stratigraphical ranges reflect the placement of FO and LO of stratigraphically useful species as recognized by Ciesielski et al (1988) andCiesielski (1991). The revised chronozones and diatom zones illustrated are based on reassessing the data sets of these workers (Table 23).…”

Section: Hole 697bmentioning

confidence: 79%

“…Calcareous nannofossils are present in the sediments, but consist of long ranging species which are probably reworked (Ciesielski et al 1988). The integrated biostratigraphical and magnetostratigraphical data previously used (palaeomagnetics: Clement & Hailwood 1991;diatoms: Ciesielski et al 1988;Ciesielski 1991;calcareous nannofossils: none;radiolarians: Ciesielski et al 1988) and calibrated to the GPTS of Berggren et al (1985a, b) are shown in Table 20 An agedepth graph for Hole 114-701A using this data is shown in Fig. 27.…”

Section: Hole 697bmentioning

confidence: 99%

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1999

Memoirs

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Biochronological models for the Southern Ocean have developed since the mid 1960s and early 1970s and have accompanied the completion of numerous biostratigraphical studies during the last 30 years. The voluminous bibliographic literature available for discussion has been limited here to selected articles that focus primarily on the development of diatom and radiolarian stratigraphies and the calibration of these stratigraphies to a Geopolarity Timescale (GPTS). This focused discussion reflects the emphasis of these stratigraphies in this current study.Prior to the DSDP and the ODP expeditions to the Southern Ocean, calibration of microfossil datums to a magnetostratigraphy was limited to stratigraphical successions obtained from relatively short piston cores (generally less than 10 m). This practice established age constraints for microfossil datums within the uppermost sedimentary sequence, i.e. approximately the last 4 million years. Age determination for older sequences was based on estimates derived from secondary and indirect correlations to a magneto-stratigraphy. The introduction of DSDP and ODP cruises to the Southern Ocean, commencing with Leg 28 (Hays et al. 1975) and continuing through Leg 120 (Wise et al. 1992) has both expanded the geographical coverage and the stratigraphical extent of sequences in which direct calibration of biostratigraphical data is possible.The current Cenozoic biochronological framework results directly from the eight DSDP and ODP Southern Ocean expeditions (DSDP Legs 28, 35, 36, 71; ODP Legs 113, 114, 119, and 120). The biochronological framework has been refined with each expedition, as additional sedimentary sequences with integrated magnetostratigraphical and biostratigraphical records were recovered.

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Section: Hole 697bsupporting

confidence: 72%

Section: Hole 697bmentioning

confidence: 79%

Section: Hole 697bmentioning

confidence: 99%

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1999

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“…These interglacial stages also coincide with maximtun abundances of nannofossils in hole 704A with the assemblage being dominated by small placoliths (Emiliania huxleyi and Gephyrocapsa spp.) [Gard and Crux, 1991]. A thin layer of upper Quaternary calcareous ooze has also been reported from ODP leg 113 sites throughout the Weddell Sea [Kennett and Barker, 1990, p. 957].…”

Section: Discussionmentioning

confidence: 79%

“…He suggested that •e maximum southward displacement of the STC occurred during isotopic stage 11 when it was at 42øS and during early isotopic stage 5 when it was located south of 40øS. Although stage 5 does not stand out as an extremely warm period in either the oxygen isotopic or carbonate record of hole 704A (Figures 3 and 5a), maximum abundance of the subtropical coccolith Calcidiscus leptoporus in hole 704A suggests that surface waters were warmest during stage 5e [Gard and Crux, 1991]. It is likely that this short interval of intense warmth associated with the early part of stage 5 (i.e., 5e) was missed by our relatively wide sampling interval in hole 704A.…”

Section: Discussionmentioning

confidence: 99%

Late Pleistocene Paleoceanography of the South Atlantic Sector of the Southern Ocean: Ocean Drilling Program Hole 704A

Hodell¹

1993

Paleoceanography

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Isotopic and sedimentologic data from Ocean Drilling Program hole 704A suggest that isotopic stages 7, 9, and 11 were marked by unusually strong interglacial conditions in surface waters of the southern ocean. During interglacial stages 9 and 11, warm surface waters penetrated far poleward and may have led to destabilization of the West Antarctic Ice Sheet. In contrast, the strongest glacial conditions in surface waters of the subantarctic South Atlantic occurred during oxygen isotopic stage 12. Comparisons of benthic carbon isotopic gradients between sites located in the North Atlantic, southern ocean, and Pacific indicate that the production of upper North Atlantic Deep Water (uNADW) was strongest during stages 7,9, and 11 and weakest during stage 12, These results suggest a possible link between the flux of uNADW and paleoceanographic change in the southern ocean and support the traditional NADW‐Antarctic connection whereby increased NADW leads to warming of the southern ocean.

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