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Paleomagnetism and biostratigraphy of sediments from Southern Ocean ODP Site 744 (southern Kerguelen Plateau): Implications for early-to-middle Miocene climate in Antarctica

Paleomagnetism and biostratigraphy of sediments from Southern Ocean ODP Site 744 (southern Kerguelen Plateau): Implications for early-to-middle Miocene climate in Antarctica
Paleomagnetism and biostratigraphy of sediments from Southern Ocean ODP Site 744 (southern Kerguelen Plateau): Implications for early-to-middle Miocene climate in Antarctica
New paleomagnetic results from lower-to-middle Miocene samples from Ocean Drilling Program (ODP) Holes 744A and 744B, cored during ODP Leg 119 on the southern Kerguelen Plateau (Indian Ocean sector; Southern Ocean), provide a chronostratigraphic framework for an existing and under-utilized paleoclimate archive during a key period of Antarctic climate and ice sheet evolution. Site 744 is strategically positioned for high-latitude paleoceanographic and paleoclimatic studies because it lies within the southern domain of the Antarctic Circumpolar Current (ACC) and in proximity to the large and active Lambert Glacier-Amery Ice Shelf drainage system of the East Antarctic Ice Sheet. Magnetostratigraphic results were reported previously for this site, but technical difficulties and limited sampling prevented confident correlation of the magnetic polarity record with the geomagnetic polarity timescale. Our results, which are constrained by new semi-quantitative analyses of diatom assemblages and radiolarian first and last appearance events that are evaluated within a regional Southern Ocean biostratigraphic dataset through Constrained Optimization (CONOP) model runs, permit significant refinement of previous age models for the lower-to-middle Miocene sequence recovered at Site 744 (spanning the interval from ~ 21 to 13.7 Ma). An extended record of sediment accumulation, with average sedimentation rates of ~ 0.7–0.9 cm/kyr, is interrupted by a series of hiatuses in the middle Miocene. These disruptions in sediment supply, or erosional events, could mark a local response of north–south fluctuations in the location and/or strength of the Antarctic Circumpolar Current during transient glacial events within the Mid-Miocene Climate Optimum (MMCO; ~ 17 to 14.45 Ma). With the enhanced age control provided by this study, combined with a refined chronostratigraphy for the underlying upper Eocene to Oligocene strata, Site 744 becomes a good candidate for future high-resolution stable isotope and microfossil paleoecological work, which will further elucidate the late Paleogene and early Neogene paleoenvironmental history of the Southern Ocean.
Antarctica, Paleoclimate, Miocene, Diatom biostratigraphy, Paleomagnetism, CONOP, Kerguelen Plateau
0921-8181
434-454
Florindo, Fabio
5953170b-79f7-431e-9e08-824a47e0fbd5
Farmer, Ryan K.
199d3611-6676-43fa-86fa-34b380175af0
Harwood, David M.
e97f3fc0-b55b-4d56-a61e-b7d5b9b83a46
Cody, Rosemary D.
e0db796a-5d39-4159-b39e-e4cabc82c933
Levy, Richard
bf048fb8-4f59-4c95-b9d4-bef2454bb7c1
Bohaty, Steven M.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Carter, Lionel
f2e2fad2-17fc-45c4-b631-fd0b2e451911
Winkler, Aldo
65ea99d5-825c-4ec9-9961-5dc5dd9b8bd8
Florindo, Fabio
5953170b-79f7-431e-9e08-824a47e0fbd5
Farmer, Ryan K.
199d3611-6676-43fa-86fa-34b380175af0
Harwood, David M.
e97f3fc0-b55b-4d56-a61e-b7d5b9b83a46
Cody, Rosemary D.
e0db796a-5d39-4159-b39e-e4cabc82c933
Levy, Richard
bf048fb8-4f59-4c95-b9d4-bef2454bb7c1
Bohaty, Steven M.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Carter, Lionel
f2e2fad2-17fc-45c4-b631-fd0b2e451911
Winkler, Aldo
65ea99d5-825c-4ec9-9961-5dc5dd9b8bd8

Florindo, Fabio, Farmer, Ryan K., Harwood, David M., Cody, Rosemary D., Levy, Richard, Bohaty, Steven M., Carter, Lionel and Winkler, Aldo (2013) Paleomagnetism and biostratigraphy of sediments from Southern Ocean ODP Site 744 (southern Kerguelen Plateau): Implications for early-to-middle Miocene climate in Antarctica. Global and Planetary Change, 110 (C), 434-454. (doi:10.1016/j.gloplacha.2013.05.004).

Record type: Article

Abstract

New paleomagnetic results from lower-to-middle Miocene samples from Ocean Drilling Program (ODP) Holes 744A and 744B, cored during ODP Leg 119 on the southern Kerguelen Plateau (Indian Ocean sector; Southern Ocean), provide a chronostratigraphic framework for an existing and under-utilized paleoclimate archive during a key period of Antarctic climate and ice sheet evolution. Site 744 is strategically positioned for high-latitude paleoceanographic and paleoclimatic studies because it lies within the southern domain of the Antarctic Circumpolar Current (ACC) and in proximity to the large and active Lambert Glacier-Amery Ice Shelf drainage system of the East Antarctic Ice Sheet. Magnetostratigraphic results were reported previously for this site, but technical difficulties and limited sampling prevented confident correlation of the magnetic polarity record with the geomagnetic polarity timescale. Our results, which are constrained by new semi-quantitative analyses of diatom assemblages and radiolarian first and last appearance events that are evaluated within a regional Southern Ocean biostratigraphic dataset through Constrained Optimization (CONOP) model runs, permit significant refinement of previous age models for the lower-to-middle Miocene sequence recovered at Site 744 (spanning the interval from ~ 21 to 13.7 Ma). An extended record of sediment accumulation, with average sedimentation rates of ~ 0.7–0.9 cm/kyr, is interrupted by a series of hiatuses in the middle Miocene. These disruptions in sediment supply, or erosional events, could mark a local response of north–south fluctuations in the location and/or strength of the Antarctic Circumpolar Current during transient glacial events within the Mid-Miocene Climate Optimum (MMCO; ~ 17 to 14.45 Ma). With the enhanced age control provided by this study, combined with a refined chronostratigraphy for the underlying upper Eocene to Oligocene strata, Site 744 becomes a good candidate for future high-resolution stable isotope and microfossil paleoecological work, which will further elucidate the late Paleogene and early Neogene paleoenvironmental history of the Southern Ocean.

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More information

Published date: November 2013
Keywords: Antarctica, Paleoclimate, Miocene, Diatom biostratigraphy, Paleomagnetism, CONOP, Kerguelen Plateau
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 360433
URI: https://eprints.soton.ac.uk/id/eprint/360433
ISSN: 0921-8181
PURE UUID: b0025c82-e4cf-44d4-b71f-453f733f2ace
ORCID for Steven M. Bohaty: ORCID iD orcid.org/0000-0002-1193-7398

Catalogue record

Date deposited: 09 Dec 2013 11:57
Last modified: 06 Jun 2018 12:39

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