Publication Date:
2022-06-14
Description:
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.
Description:
Published
Description:
46-66
Description:
2.2. Laboratorio di paleomagnetismo
Description:
JCR Journal
Description:
reserved
Keywords:
Eocene
;
Oligocene
;
Ocean Drilling Program
;
Sites 689 and 690
;
Maud Rise
;
Antarctica
;
magnetostratigraphy
;
03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
;
04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport
;
04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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