Magnetobiostratigraphic Synthesis of Leg 123: Sites 765 and 766 (Argo Abyssal Plain and Lower Exmouth Plateau)

Kaminski, Michael A., Baumgartner, P. O., Bown, P. R., Haig, D. W., McMinn, A., Moran, M. J., Mutterlose, J. and Ogg, J. G. (1992) Magnetobiostratigraphic Synthesis of Leg 123: Sites 765 and 766 (Argo Abyssal Plain and Lower Exmouth Plateau) Proceedings of the Ocean Drilling Program: Scientific Results, 123 . pp. 717-737. DOI 10.2973/odp.proc.sr.123.115.1992.

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Abstract

During ODP Leg 123, Sites 765 and 766 were drilled to examine the tectonic evolution, sedimentary history, and paleoceanography of the Argo Abyssal Plain and lower Exmouth Plateau. At each site, the quality of magnetostratigraphic and biostratigraphic records varies because of complicating factors, such as the predominance of turbidites, the presence of condensed horizons, or deposition beneath the CCD. Based primarily on the presence of nannofossils, the base of the sedimentary section at Site 765 was dated as Tithonian. A complete Cretaceous sequence was recovered at this site, although the sedimentation rate varies markedly through the section. The Cretaceous/Tertiary boundary is represented by a condensed horizon. The condensed Cenozoic sequence at Site 765 extends from the upper Paleocene to the lower Miocene. A dramatic increase in sedimentation rate was observed in the lower Miocene, and a 480-m-thick Neogene section is present. The Neogene section is continuous, except for a minor hiatus in the lower Pliocene. The base of the sedimentary section at Site 766 is Valanginian, in agreement with the site's position on marine magnetic anomaly Mil. Valanginian to Barremian sediments are terrigenous, with variable preservation of microfossils, and younger sediments are pelagic, with abundant well-preserved microfossils. Sedimentation rate is highest in the Lower Cretaceous and decreases continually upsection. Upper Cenozoic sediments are condensed, with several hiatuses.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: No
DOI etc.: 10.2973/odp.proc.sr.123.115.1992
ISSN: 1096-7451
Projects: ODP
Date Deposited: 14 May 2019 13:54
Last Modified: 14 May 2019 13:54
URI: http://eprints.uni-kiel.de/id/eprint/46720

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