East Antarctic Ice Sheet fluctuations during the Middle Miocene Climatic Transition inferred from faunal and biogeochemical data on planktonic

• Main Authors: Foraminifera (odp Hole A, Kerguelen Plateau
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; East Antarctic Ice Sheet; Kerguelen; Southern Ocean; Antarc*; Antarctica; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.505.8817; http://pubs.usgs.gov/of/2007/1047/srp/srp037/of2007-1047srp037.pdf

Abstract This research focuses on a detailed study of faunal and biogeochemical changes that occurred at ODP Hole 747A in the Kerguelen Plateau region of the Southern Ocean during the middle Miocene (14.8-11.8 Ma). Abundance fluctuations of several planktonic foraminiferal taxa, stable oxygen isotope and Mg/Ca ratios have been integrated as a multi-proxy approach to reach a better understanding of the growth modality and fluctuations of the East Antarctic Ice Sheet (EAIS) during this period. A 7°C decrease in Sea Surface Temperature (SST), an abrupt turnover in the planktonic foraminiferal assemblage, a 1.5 ‰ shift towards heavier δ18O values (Mi3 event) and a related shift towards heavier seawater δ18O values between 13.9 and 13.7 Ma, are interpreted to reflect rapid surface water cooling and EAIS expansion. Hole 747A data suggest a major change in the variability of the climate system fostered by EAIS expansion between 13.9 and 13.7 Ma. Ice sheet fluctuations were greater during the interval 14.8-13.9 Ma compared with those from 13.7 to 11.8 Ma, whereas the latter interval was characterized by a more stable EAIS. In our opinion, the middle Miocene ice sheet expansion in Antarctica represents a first step towards the development of the modern permanent ice