Southern Ocean Pleistocene calcareous nannofossil events: calibration with isotope and geomagnetic stratigraphies
Introduction
Over the last decades calcareous nannofossils have shown excellent potential in Pleistocene biostratigraphy. Improved isotope and magnetostratigraphic data have permitted the calibration of the calcareous nannofossil data, allowing a more precise correlation between different regions, and consequently, the dating of paleoceanographic events. Accurate age determination and the evaluation of synchrony of micropaleontological data are essential in paleoceanographic analyses to provide age-control points, which then help to infer ages or to interpret isotope stratigraphy. Such analyses are also important in paleoecological studies on the Pleistocene, a time interval of special relevance in the understanding of climate evolution and cyclicity. Examples of these biochronological data come from Thierstein et al., 1977, Gartner, 1977, Pujos-Lamy, 1977, Matsuoka and Okada, 1990, Giraudeau and Pujos, 1990, Wei, 1993, Raffi et al., 1993, Weaver and Thomson, 1993, Pujos and Giraudeau, 1993, Wells and Okada, 1997, Hine and Weaver, 1998, Bollmann et al., 1998 among others. However, most of the above studies focus on middle- and low-latitude sections and only few of them are based on material recovered in the Southern Ocean, which plays an important role in climatic and oceanic evolution (Kennet and Barron, 1992, Shipboard et al., 1999). The present study focuses on the identification and calibration of calcareous nannofossil biostratigraphic data in order to improve the stratigraphic framework for southern high-latitude paleoceanographic studies.
The zonations of Martini, 1971, Okada and Bukry, 1980 for Quaternary nannofossil Pleistocene biostratigraphy were improved when quantitative data and new deep-sea material became available. Several authors, cited previously in this section, generated new higher-resolution schemes, in most cases calibrated chronologically. Worldwide events were observed, mainly in tropical and in temperate water masses, due to the cosmopolitan characteristics of most of the species involved (Raffi et al., 1993, Wei, 1993).
As mentioned above, stratigraphic studies carried out on Pleistocene material from the Southern Ocean in general disclose low sedimentation rates and/or hiatuses of different stratigraphic extent (Wise and Wind, 1977, Wise, 1983, Crux, 1991, Wei and Wise, 1992). In other cases, at these latitudes the calcareous plankton is in general diluted by siliceous organisms or is affected by dissolution. Consequently, the number of sections available is restricted. To these factors should be added restrictions in ecological calcareous nannofossil marker species. Alternative quantitative events to the “standard” can improve stratigraphic resolution in this region.
Section snippets
Core location and lithology
The five piston cores studied were recovered during the RV Polarstern cruises ANT IX/4, XI/2 and XII/4 in the Atlantic and the Pacific sectors of the Southern Ocean (Bathmann et al., 1992, Gersonde et al., 1995) (Fig. 1, Table 1).
Core PS2487-6 was recovered on the continental slope south of the African Cape and thus represents the only core addressed in this paper that originates from southern subtropical waters. The core location is in the vicinity of DSDP Site 360 (Bolli et al., 1978) and
Calcareous nannofossil taxonomy
The species involved in this study are mainly included within the family Noelaerhabdaceae (Reticulofenestrids including the genera Emiliania, Pseudoemiliania, Gephyrocapsa and Reticulofenestra) (Thierstein et al., 1977, Pujos-Lamy, 1977, Wei, 1993, Raffi et al., 1993, Weaver and Thomson, 1993). However, the taxonomy of this group is complex and confusing, mainly due to a proliferation of species names and morphotypes. Here we adopted the ideas of Raffi et al. (1993) for the morphological
Results and analyses
For the present study, a detailed calcareous nannofossil range chart for Core PS2487-6 was constructed (see Appendix Table A1). Quantitative analyses for the upper 500 cm (last 13 MIS) have been presented previously by Flores et al. (1999). Here we include analyses from the base of the core. Calcareous nannofossils from core PS2487-6 are abundant, and their preservation is good. Fig. 2 and Table 4 show the calcareous nannofossil events and their relationship with the isotope curve. A hiatus
Acme base
The base of the Emiliania huxleyi Acme is a diachronous event and is difficult to recognise in certain areas of the ocean (Jordan et al., 1996). Gartner (1977) dated the E. huxleyi Acme bottom at 70 ky. Thierstein et al. (1977) proposed the use of the so-called “Reversal in abundance of Gephyrocapsa caribbeanica−E. huxleyi” (=Gephyrocapsa muellerae−E. huxleyi, dated at 73–85 ky), as a biostratigraphic event. This event was identified by Gard and Crux (1991) as having occurred during the MIS 4/5
Conclusions
Ten Pleistocene calcareous nannofossil events calibrated with oxygen isotope and paleomagnetic stratigraphies and correlated with low and middle latitude stratigraphies are discussed.
The events identified are based on some species of Noelaerhabdaceae (Reticulofenestrids), which are cosmopolitan and facilitate correlations between high, middle, and low latitudes.
“Standard” events such as the FO of Emiliana huxleyi and the LO of Pseudoemiliana lacunosa, calibrated by Thierstein et al. (1977) at
Acknowledgements
The authors wish to express their thanks to Dr Alexandra Negri and Dr Kazuhiro Sugiyama for their valuable review and suggestions. N.S.D. Skinner is acknowledged for revising the English version of the MS. Isotope measurements were accomplished in the AWI isotope laboratory under the helpful guidance of Dr A. Mackensen. Research grants CICYT ANT97-1909-E, CLI-1002-CO2-02 and the Spanish–German Integrated Actions supported this study.
References (42)
- et al.
Pleistocene fluctuations in the Agulhas Current Retroflection based on the calcareous plankton record
Mar. Micropaleontol.
(1999) Calcareous nannofossil biostratigraphy and revised zonation of the Pleistocene
Mar. Micropaleontol.
(1977)- et al.
Supplementary modification and introduction of code numbers to the low-latitude coccolith biostratigraphic zonation (Bukry, 1973; 1975)
Mar. Micropaleontol.
(1980) - et al.
Response of nannoplankton to major changes in sea-surface temperature and movements of hydrological fronts over Site DSDP 594 (south Chatham Rise, southeastern New Zealand), during the last 130 kyr
Mar. Micropaleontol.
(1997) - Bathmann, U., Schulz-Baldes, M., Fahbach, E., Smetacek, V., Hubberten, H.-W., 1992. Die Expedition ANTARKTIS IX/1-4 des...
- et al.
Init. Repts. Deep Sea Drilling Project
(1978) Morphology and biogeography of the genus Gephyrocapsa coccoliths, in Holocene sediments
Mar. Micropaleontol.
(1977)- et al.
Global dominance of Gephyrocapsa coccoliths in the late Pleistocene: selective dissolution, evolution, or global environmental change?
Paleoceanography
(1998) Formes nouvelles quaternaires et actuelles de la famille Gephyrocapsaceae (Coccolithophorides)
C.R. Acad. Sci. Paris, Ser. D
(1978)Coccolith stratigraphy — eastern equatorial Pacific, Leg 16, Deep Sea Drilling Project
Init. Repts. Deep Sea Drilling Project
(1973)
A new geomagnetic polarity time scale for the Late Cretaceous and Cenozoic
J. Geophys. Res.
Calcareous nannofossils recovered by Leg 114 in the Subantarctic South Atlantic Ocean
Proc. Ocean Drilling Program, Sci. Resuts
Quaternary calcareous nannofossil biostratigraphy: the eastern Arctic Ocean record
Preliminary results from Hole 704A: Arctic–Antarctic correlation through nannofossil biochronology
Proc. Ocean Drilling Program, Sci. Results
Geological record and reconstruction of the late Pliocene impact of the Eltanin asteroid in the Southern Ocean
Nature
Fontion de transfer besée sur les nannofossiles calcaires du Pleistocène des Caribes
Oceanol. Acta
Quaternary
Coccolith and alkenone stratigraphy and palaeoceanography at an upwelling site off NW Africa (ODP 658C) during the last 130,000 years
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