The University of Southampton
University of Southampton Institutional Repository

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

Eocene-Oligocene magnetobiochronology of ODP sites 689 and 690, Maud Rise, Weddell Sea, Antarctica
Eocene-Oligocene magnetobiochronology of ODP sites 689 and 690, Maud Rise, Weddell Sea, Antarctica
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.
Eocene, Oligocene, Ocean Drilling Program, Site 689, Site 690, Maud Rise, Antarctica, magnetostratigraphy
0016-7606
46-66
Florindo, F.
8782f358-6dd8-4531-aaf1-4e1e859d52db
Roberts, A.P.
4497b436-ef02-428d-a46e-65a22094ba52
Florindo, F.
8782f358-6dd8-4531-aaf1-4e1e859d52db
Roberts, A.P.
4497b436-ef02-428d-a46e-65a22094ba52

Florindo, F. and Roberts, A.P. (2005) Eocene-Oligocene magnetobiochronology of ODP sites 689 and 690, Maud Rise, Weddell Sea, Antarctica. Geological Society of America Bulletin, 117 (1-2), 46-66. (doi:10.1130/B25541.1).

Record type: Article

Abstract

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.

This record has no associated files available for download.

More information

Published date: 2005
Keywords: Eocene, Oligocene, Ocean Drilling Program, Site 689, Site 690, Maud Rise, Antarctica, magnetostratigraphy

Identifiers

Local EPrints ID: 14856
URI: http://eprints.soton.ac.uk/id/eprint/14856
ISSN: 0016-7606
PURE UUID: 504bfc98-a7f4-4848-bf56-ced440d15523

Catalogue record

Date deposited: 07 Mar 2005
Last modified: 15 Mar 2024 05:32

Export record

Altmetrics

Contributors

Author: F. Florindo
Author: A.P. Roberts

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×