Antarctic Peninsula Climate Variability:
APRIL 3-5, 2002
| Relationship of Millennial
Antarctic Ice Discharge Events with Environmental and Climate Proxies
Sharon L. Kanfoush1,2 and David A. Hodell2
¹Department of Geology, Utica College of Syracuse
University, Utica, New York 13502
Building on our previous correlation of South Atlantic sediments to Greenland ice (GISP2) using benthic δ¹³C, we correlate the marine record also to Byrd as transferred onto the GISP2 age-model via correlation of atmospheric methane concentration. The resulting correlation predicts prominent South Atlantic millennial ice-rafting events (SA events) coincide with the initiation of regional cooling. Exploiting the high sedimentation rates at Sites 1089 and 1094 (~18 cm/kyr and ~25 cm/kyr, respectively) in the southeast Atlantic, we enumerate the sequence of events surrounding millennial ice-rafted debris (IRD) peaks of the last glaciation to test this prediction.
The planktic δ18O signal at 41°S records a series of rapid oscillations and bears a strong resemblance to temperature proxy records in Antarctic ice. Marine-ice core correlation is therefore achieved by aligning prominent features common to each record. The resulting correlation suggests SA events marine isotope stage (MIS) 3 occur near in time, but are not synchronous with, Antarctic warm events. Downcore phase relationships further constrain the relative timing. Inferred warm-cold oscillations of recorded at 41°S appear to be grouped into longer-term bundles, somewhat analogous to Bond Cycles of the North Atlantic region, within which SA events occur. However, unlike North Atlantic Heinrich events which occur at the culmination of Bond Cycle cooling, SA events of MIS 3 occur comparably early in the cooling cycle and the amount of lag between peak Antarctic warmth and IRD deposition is variable. The observed phase relationships do not eliminate Antarctic climate as the trigger of Antarctic ice discharge. However, if SA events are climatically driven, the synchronous relationship between SA events and North Atlantic interstadials during MIS 3 points to this region as a more likely candidate for this interval.