Data Description

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Citation:
Rommerskirchen, F et al. (2011): (Table 1) TOC content, BIT, TEX86 and UK'37 indices, and sea surface temperature reconstruction for the middle Miocene to Pliocene of ODP Hole 175-1085A. doi:10.1594/PANGAEA.770426,
Supplement to: Rommerskirchen, Florian; Condon, Tegan; Mollenhauer, Gesine; Dupont, Lydie M; Schefuß, Enno (2011): Miocene to Pliocene development of surface and subsurface temperatures in the Benguela Current system. Paleoceanography, 26, PA3216, doi:10.1029/2010PA002074
Abstract:
The initiation of the Benguela upwelling has been dated to the late Miocene, but estimates of its sea surface temperature evolution are not available. This study presents data from Ocean Drilling Program (ODP) Site 1085 recovered from the southern Cape Basin. Samples of the middle Miocene to Pliocene were analyzed for alkenone-based (UK'37, SSTUK) and glycerol dialkyl glycerol tetraether (GDGT) based (TEX86, TempTEX) water temperature proxies. In concordance with global cooling during the Miocene, SSTUK and TempTEX exhibit a decline of about 8°C and 16°C, respectively. The temperature trends suggest an inflow of cold Antarctic waters triggered by Antarctic ice sheet expansion and intensification of Southern Hemisphere southeasterly winds. A temperature offset between both proxies developed with the onset of upwelling, which can be explained by differences in habitat: alkenone-producing phytoplankton live in the euphotic zone and record sea surface temperatures, while GDGT-producing Thaumarchaeota are displaced to colder subsurface waters in upwelling-influenced areas and record subsurface water temperatures. We suggest that variations in subsurface water temperatures were driven by advection of cold Antarctic waters and thermocline adjustments that were due to changes in North Atlantic deep water formation. A decline in surface temperatures, an increased offset between temperature proxies, and an increase in primary productivity suggest the establishment of the Benguela upwelling at 10 Ma. During the Messinian Salinity Crisis, between 7 and 5 Ma, surface and subsurface temperature estimates became similar, likely because of a strong reduction in Atlantic overturning circulation, while high total organic carbon contents suggest a "biogenic bloom." In the Pliocene the offset between the temperature estimates and the cooling trend was reestablished.
Project(s):
Coverage:
Latitude: -29.374410 * Longitude: 13.990110
Minimum Age: 15.000 ka BP * Maximum Age: 14381.000 ka BP
Minimum DEPTH, sediment/rock: 0.5 m * Maximum DEPTH, sediment/rock: 603.8 m
Event(s):
175-1085A * * Latitude: -29.374410 * Longitude: 13.990110 * Date/Time Start: 1997-09-26T00:15:00 * Date/Time End: 1997-09-29T18:15:00 * Elevation: -1713.2 m * Recovery: 594.39 m * Penetration: 604.00 m * Location: Benguela Current, South Atlantic Ocean * * Campaign: Leg175 * * Basis: Joides Resolution * * Device: Drilling/drill rig * * Comment: 64 cores; 604 m cored; 0 m drilled; 98.4 % recovery
Comment:
Sediment depth is given in mbsf. Age is after Berger et al. (2002, doi:10.2973/odp.proc.sr.175.235.2002), Vidal et al. (2002, doi:10.1016/S0025-3227(01)00206-7), and Westerhold et al. (2005, doi:10.1016/j.palaeo.2004.12.001).
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Sample code/label *LabelRommerskirchen, Florian *ODP sample designation *
2Sample thickness *Samp thickcmRommerskirchen, Florian *
3DEPTH, sediment/rock *DepthmGeocode
4Depth, composite *Depth compmcdRommerskirchen, Florian *Intercore correlation *log depth after Wefer et al. (1998, doi:10.2973/odp.proc.ir.175.1998)
5AGE *Ageka BPGeocode
6Carbon, organic, total *TOC%Rommerskirchen, Florian *Element analyser CHN-O Rapid, Heraeus *
7Alkenone, unsaturation index UK'37 *UK'37Rommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
8Alkenone, unsaturation index UK37, standard deviation *UK37 std dev±Rommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
9Sea surface temperature, annual mean *SST (1-12)°CRommerskirchen, Florian *Calculated from UK'37 (Müller et al, 1998) *
10Sea surface temperature, annual mean standard deviation *SST (1-2) std dev±Rommerskirchen, Florian *Calculated from UK'37 (Müller et al, 1998) *
11Branched and isoprenoid tetraether index *BITRommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
12Branched and isoprenoid tetraether index, standard deviation *BIT std dev±Rommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
13Tetraether index of 86 carbon atoms *TEX86Rommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
14Tetraether index of 86 carbon atoms, standard deviation *TEX86±Rommerskirchen, Florian *High Performance liquid chromatography coupled mass spectrometer (HPLC-MS) *
15Sea surface temperature, annual mean *SST (1-12)°CRommerskirchen, Florian *Calculated from TEX86 (Kim et al., 2010) *
16Sea surface temperature, annual mean standard deviation *SST (1-2) std dev±Rommerskirchen, Florian *Calculated from TEX86 (Kim et al., 2010) *
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Size:
1483 data points

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