FN Archimer Export Format
PT J
TI Antarctic Polar Front migrations in the Kerguelen Plateau region, Southern Ocean, over the past 360 kyrs
BT 
AF Civel-Mazens, M.
   Crosta, X.
   Cortese, G.
   Michel, E.
   Mazaud, A.
   Ther, O.
   Ikehara, M.
   Itaki, T.
AS 1:1,2;2:3;3:4;4:5;5:5;6:3;7:1,6;8:2;
FF 1:;2:;3:;4:;5:;6:;7:;8:;
C1 Graduate School of Integrated Arts and Sciences, Kochi University, Japan
   Geological Survey of Japan (AIST), Tsukuba, Japan
   Université de Bordeaux, CNRS, EPHE, UMR 5805 EPOC, Pessac, France
   GNS Science, Lower Hutt, New Zealand
   Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette, France
   Center for Advanced Marine Core Research, Kochi University, Japan
C2 UNIV KOCHI, JAPAN
   GEOL SURVEY JAPAN AIST, JAPAN
   UNIV BORDEAUX, FRANCE
   GNS SCIENCE, NEW ZEALAND
   LSCE, FRANCE
   UNIV KOCHI, JAPAN
IF 4.956
TC 15
UR https://archimer.ifremer.fr/doc/00696/80832/84409.pdf
LA English
DT Article
CR MD 185 / INDIEN SUD 1
   MD 189 / INDIEN SUD 2
BO Marion Dufresne
DE ;Southern Ocean;Fronts;Kerguelen;Radiolarians;Diatoms
AB In the Southern Ocean (SO), climate-driven latitudinal migrations of the Antarctic Circumpolar Current (ACC) frontal system impact large-scale ocean circulation and primary productivity. Latitudinal migrations may not have been identical in all SO basins due to the presence or absence of regional bathymetric obstacles. The Antarctic Polar Front (APF), defined by the 3–5 °C surface temperature range and the 2 °C subsurface temperature minimum at 200 m, is particularly important for nutrient redistribution and biodiversity, influencing the soft tissue carbon pump in the modern SO. However, previous assessments of its migrations in the past, mostly based on a single metric or indirect observations, were not always robust. Here, we combine a new proxy for subsurface temperature (sub-ST) reconstructions based on radiolarian assemblages (sub-STrad), with relative abundance variations of key radiolarian species, and sea-surface temperatures (SST) reconstructions, based on diatom assemblages (SSTdiat), to refine estimations of the past mean APF locations in the Kerguelen Plateau (KP) region. Data from three sediment cores on a south (55°S) to north (47°S) transect are used to trace the mean APF locations for three climate states, glacials, peak-interglacials and mild-interglacials. Our results suggest that the APF, presently located south of Kerguelen Islands, shifted by 6–7 degrees of latitude and was located north of the KP during all glacial periods of the last 360 kyrs. This suggests that the ACC major flow interacted less with the bottom topography relative to its modern counterpart, probably resulting in less mixing of the water column over and in the lee of the KP. We propose that this process participated in the isolation of Antarctic surface waters (AASW) and in the reduction of macro-nutrient supply, thus resulting in lower regional productivity. During the warmer-than-present early interglacial periods, the APF probably migrated south by ~5 degrees of latitude relative to its modern position, to pass through the Fawn Trough. Contrary to glacial periods, the APF was forced in an “S” shape while the ACC main flow was constrained against the northern tip of the KP. In this configuration, a stronger interaction between the ACC, its associated fronts, and topography is expected, resulting in more mixing of the water column over and east of the KP. Congruently, siliceous productivity was probably restrained to latitudes south of the Fawn Trough. 
PY 2021
PD JUN
SO Global And Planetary Change
SN 0921-8181
PU Elsevier BV
VL 202
UT 000663732300001
DI 10.1016/j.gloplacha.2021.103526
ID 80832
ER

EF