Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Florindo, F. Articles by Roberts, A. P. Search for Related Content GeoRef GeoRef Citation

Eocene-Oligocene magnetobiochronology of ODP Sites 689 and 690, Maud Rise, Weddell Sea, Antarctica

Fabio Florindo^,1 and Andrew P. Roberts²

¹ Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605, I-00143 Rome, Italy, and Southampton Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK
² Southampton Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK

Magnetostratigraphic studies of Paleogene sediments piston-cored on Maud Rise, Weddell Sea (ODP Sites 689 and 690), are a cornerstone of Southern Ocean Paleogene and Neogene chronostratigraphy. However, parts of previous magnetostratigraphic interpretations have been called into question, and recent reinvestigation of the upper Paleocene–middle Eocene portion of Site 690 suggested that the records might be contaminated by spurious magnetizations, which raises doubts about the reliability of these important records. We undertook a high-resolution magnetostratigraphic study of Eocene-Oligocene u-channel samples from ODP Holes 689B, 689D, 690B, and 690C in order to address these concerns. A pervasive overprint appears to be present below the middle Eocene, which compromises magnetobiostratigraphic interpretations for the upper Cretaceous and lower Paleogene. Nevertheless, our new results provide a robust record of geomagnetic field behavior from 38.5 to 25 Ma and confirm the reliability of these sediments for calibration of biostratigraphic datum events during a crucial phase of earth history when major Antarctic ice sheets developed. Also, comparison of magnetozone thicknesses in multiple holes at the same site indicates that 1.2–1.8 m of the stratigraphic record is missing at each core break, which corresponds to time breaks of 120–360 k.y. Lack of a continuous record within a single hole renders useless spectral analyses for investigating long geomagnetic and paleoclimatic time series. This observation reinforces the need for coring of multiple offset holes to obtain continuous paleoceanographic records. Sedimentary hiatuses have been identified only at the deeper of the two investigated sites (Site 690), which could mark a local response to the onset of the Antarctic Circumpolar Current.

Key Words: Eocene • Oligocene • Ocean Drilling Program • 689 • 690 • Maud Rise • Antarctica • magnetostratigraphy

This article has been cited by other articles:

				L. Jovane, F. Florindo, R. Coccioni, J. Dinares-Turell, A. Marsili, S. Monechi, A. P. Roberts, and M. Sprovieri The middle Eocene climatic optimum event in the Contessa Highway section, Umbrian Apennines, Italy Geological Society of America Bulletin, March 1, 2007; 119(3-4): 413 - 427. [Abstract] [Full Text] [PDF]

				B. T. Huber and F. Quillevere REVISED PALEOGENE PLANKTONIC FORAMINIFERAL BIOZONATION FOR THE AUSTRAL REALM Journal of Foraminiferal Research, October 1, 2005; 35(4): 299 - 314. [Abstract] [Full Text] [PDF]