10.1594/PANGAEA.727745
Kuhnert, Henning
Henning
Kuhnert
0000-0001-5242-4495
Bickert, Torsten
Torsten
Bickert
0000-0002-5221-5922
Paulsen, Harald
Harald
Paulsen
Mg/Ca ratios of Globigerina bulloides and stable isotope data of ODP Hole 177-1092B in the Southern Ocean
PANGAEA
2009
Sample code/label
DEPTH, sediment/rock
Depth, composite
Depth, composite revised
AGE
Cibicidoides kullenbergi, δ13C
Cibicidoides kullenbergi, δ18O
Globigerina bulloides, δ13C
Globigerina bulloides, δ18O
Globigerina bulloides, Magnesium/Calcium ratio
Drilling/drill rig
DSDP/ODP/IODP sample designation
Intercore correlation
Mass spectrometer Finnigan MAT 252
ICP-MS, Thermo Finnigan, Element 2
Leg177
Joides Resolution
Ocean Drilling Program (ODP)
Shipboard Scientific Party
1998-01-08T07:50:00/1998-01-08T20:05:00
en
Supplementary Dataset
10.1016/j.epsl.2009.05.030
431 data points
text/tab-separated-values
Creative Commons Attribution 3.0 Unported
The middle Miocene climate approximately 14 Ma ago was characterized by the glaciation of Antarctica, deep-ocean cooling and variations in the global carbon cycle. Although the Southern Ocean underwent significant oceanographic changes, there is limited information on their spatial extent and timing. However, such knowledge is crucial for understanding the role of the Southern Ocean and the Antarctic Circumpolar Current (ACC) for Antarctic glaciation and the coupling between the ocean and continental climate. We have reconstructed surface temperatures and seawater oxygen isotopes at Ocean Drilling Program (ODP) Site 1092 in the Polar Frontal Zone of the Atlantic sector of the Southern Ocean from foraminiferal oxygen isotopes (d18O) and magnesium to calcium ratios (Mg/Ca). Sea surface cooling by ~ 4 °C and freshening indicated by the ~ 1per mill reduction of seawater d18O (d18Osw) at 14.2 Ma precede the major step in Antarctic ice sheet growth at 13.8–13.9 Ma. This pattern qualitatively mirrors previous findings from the Pacific sector, and we interpret the surface hydrographic changes to reflect the circum-Antarctic northward shift of the Southern Ocean fronts and specifically at Site 1092 the passage of the Subantarctic Front. The magnitude of change in reconstructed d18Osw requires a d18Osw: salinity gradient significantly higher than the modern value (~ 0.52 per mill) and it possibly exceeded 1.1 per mill. This implies the Polar Frontal Zone was influenced by freshwater derived from Antarctica, which in turn confirms higher than modern continental precipitation. The latter has previously been suggested to have contributed to Antarctic glaciation.
DEPTH, sediment = mbsf, stable isotope data were originally generated by Paulsen (2005). AGE = tuned to Sites 1085 and 1146, modified by Kuhnert, Henning
Supplement to: Kuhnert, Henning; Bickert, Torsten; Paulsen, Harald (2009): Southern Ocean frontal system changes precede Antarctic ice sheet growth during the middle Miocene. Earth and Planetary Science Letters, 284(3-4), 630-638
7.0799
-46.4118
South Atlantic Ocean