Stable isotope and Mg/Ca ratio of sediment core GeoB12610-2, supplement to: Rippert, Nadine; Baumann, Karl-Heinz; Pätzold, Jürgen (2015): Thermocline fluctuations in the western tropical Indian Ocean during the past 35 ka. Journal of Quaternary Science, 30(3), 201-210

• Main Authors: Rippert, Nadine, Baumann, Karl-Heinz, Pätzold, Jürgen
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2015
• Subjects: DEPTH, sediment/rock; AGE; Globigerinoides ruber sensu stricto, δ18O; Globigerinoides ruber sensu stricto, Magnesium/Calcium ratio; Sea surface temperature, annual mean; Sea surface temperature, annual mean, standard deviation; Neogloboquadrina dutertrei, δ18O; Neogloboquadrina dutertrei, Magnesium/Calcium ratio; Thermocline water temperature; Thermocline temperature, standard deviation; Gravity corer Kiel type; Mass spectrometer Finnigan MAT 251; ICP-OES, Inductively coupled plasma - optical emission spectrometry; Calculated from Mg/Ca ratios Dekens et al. 2002; Calculated from Mg/Ca ratios Anand et al., 2003; M75/2; Meteor 1986; Paleoenvironmental Reconstructions from Marine Sediments @ AWI AWI_Paleo; Antarctic; Southern Ocean; The Antarctic; Indian; Antarc*; Antarctica; Planktonic foraminifera
• Online Access: https://dx.doi.org/10.1594/pangaea.841927; https://doi.pangaea.de/10.1594/PANGAEA.841927

To reconstruct the still poorly understood thermocline fluctuations in the western tropical Indian Ocean, a sediment core located off Tanzania (GeoB12610-2; 04°49.00'S, 39°25.42'E, 399 m water depth) covering the last 35 ka was analysed. Mg/Ca-derived temperatures from the planktonic foraminifera Globigerinoides ruber (white) and Neogloboquadrina dutertrei indicate that the last glacial was ~2.5 °C colder in the surface waters and ~3.5 °C colder in the thermocline compared with the present day. The depth of the thermocline and thus the stratification of the water column were shallower during glacial periods and deepened during the deglaciation and Holocene. The increased inflow of Southern Ocean Intermediate Waters via 'ocean tunnels' appears to cool the thermocline from below, leading to a similarity between the thermocline record of GeoB12610-2 with the Antarctic EDML temperature curve during the glacial. With rising sea level and the corresponding greater inflow of Red Sea Waters and Indonesian Intermediate Waters, the proportion of Southern Ocean Intermediate Water within the South Equatorial Current is reduced and, by Holocene time, the correlation to Antarctica is barely traceable. Comparison with the eastern Indian Ocean reveals that the thermocline depth reverses from the last glacial to present.