Open AccessA 27 kyr terrestrial biomarker record in the southern Indian Ocean
Author(s) -
Sicre MarieAlexandrine,
Labeyrie Laurent,
Ezat Ullah,
Mazaud Alain,
Turon JeanLouis
Publication year - 2006
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2005gc001234
Subject(s) - last glacial maximum , glacial period , geology , holocene , polar front , climatology , ice core , oceanography , subtropics , paleoclimatology , marine isotope stage , physical geography , climate change , interglacial , geography , paleontology , ecology , biology
Terrestrial inputs were reconstructed using high molecular weight n ‐alkane concentrations recorded in the sub‐Antarctic Indian Ocean core MD94‐103 (45°35′S, 86°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.