A 27 kyr terrestrial biomarker record in the southern Indian Ocean

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Sicre, Marie-alexandrine, Labeyrie, Laurent, Ezat, Ullah, Mazaud, Alain, Turon, Jean-louis
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2006
• Subjects: biomarker; glacial; Indian Ocean; marine sediments; paleoclimate; terrestrial; Antarctic; Indian; Pacific; Antarc*; EPICA
• Online Access: https://archimer.ifremer.fr/doc/00234/34547/33355.pdf; https://doi.org/10.1029/2005GC001234; https://archimer.ifremer.fr/doc/00234/34547/

Terrestrial inputs were reconstructed using high molecular weight n-alkane concentrations recorded in the sub-Antarctic Indian Ocean core MD94-103 (45 degrees 35'S, 86 degrees 31'E, 3560 m) to examine regional changes in the atmospheric circulation over the last 27 kyr. This record was compared to the dust content of EPICA-Dome C ice and continental data from South Africa ( e. g., pollen sequences and isotope records in speleothems) to get a comprehensive understanding of atmospheric links between low and midlatitudes of the Indian Ocean. Terrestrial n-alkanes indicate higher glacial than Holocene inputs and marked glacial oscillations. Minimum values during the Last Glacial Maximum (LGM) are consistent with colder and drier climate and presumably caused by the persistence of subtropical anticyclones over southern Africa limiting the amount of rainfall and vegetation growth. The otherwise higher glacial n-alkanes suggest a stronger influence of the tropical rainfall in southern Africa, likely associated with a contraction of the polar vortex with respect to its LGM position. During northern Heinrich events, moderate decline of n-alkanes suggests reduced rainfall over southern Africa possibly caused by weaker tropical easterly winds when, according to Stott et al. (2002), the Pacific Ocean would have experienced Super-ENSO conditions.