Links between Patagonian Ice Sheet fluctuations and Antarctic dust variability during the last glacial period (MIS 4-2)

Abstract

a b s t r a c tAntarctic and Greenland ice-core records reveal large fluctuations of dust input on both orbital and millennial time-scales with potential global climate implications. At least during glacial periods, the Antarctic dust fluctuations appear to be largely controlled by environmental changes in southern South America. We compare dust flux records from two Antarctic ice-cores to variations in the composition of the terrigenous supply at ODP Site 1233 located off southern Chile and known to record fluctuations in the extent of the northern part of the Patagonian ice-sheet (NPIS) during the last glacial period (Marine Isotope Stage, MIS, 4 to 2). Within age uncertainties, millennial-scale glacial advances (retreats) of the NPIS correlate to Antarctic dust maxima (minima). In turn, NPIS fluctuations were closely related to offshore sea surface temperature (SST) changes. This pattern suggests a causal link involving changes in temperature, in rock flour availability, in latitudinal extensions of the westerly winds and in foehn winds in the southern Pampas and Patagonia. We further suggest that the long-term trend of dust accumulation is partly linked to the sea-level related changes in the size if the Patagonian source area due to the particular morphology of the Argentine shelf. We suggest that sea-level drops at the beginning of MIS 4 and MIS 2 were important for long-term dust increases, while changes in the Patagonian dust source regions primarily control the early dust decrease during the MIS 4/3 transition and Termination 1.

Glacial reduction and millennial-scale variations in Drake Passage throughflow

“…4), suggesting a close coupling of DP throughflow to the initiation of Southern Hemisphere warming. Similar to the glacial-interglacial pattern, our inferred millennial-scale changes in DP throughflow are paralleled by SST changes in proxy records from the Southeast Pacific (Ocean Drilling Program Site 1233) (20,40) extending north to the cold tongue in the eastern tropical Pacific (43) (Fig. 3).…”

“…The age model [updated from the work by Caniupán et al (19)] is well-constrained by radiocarbon dating, the occurrence of the Laschamp paleomagnetic excursion, and correlation to the well-dated sediment record from Ocean Drilling Program Site 1233 (20). High sedimentation rates during most of the glacial section (Fig.…”

The timing and cause of glacial advances in the southern mid-latitudes during the last glacial cycle based on a synthesis of exposure ages from Patagonia and New Zealand

“…Low Antarctic dust concentrations support the absence of glacial activity, particularly in Patagonia (Sugden et al, 2009;Kaiser & Lamy, 2010;McGee et al, 2010; Figure 8K). …”

The Southern Glacial Maximum 65,000 years ago and its Unfinished Termination

“…The MIS-4 cold period (74e59 ka ago) and its transition to the MIS-3 mild period (59e~26 ka ago) are recorded in polar ice cores (EPICA community members, 2004), marine sediments (Chapman and Shackleton, 1998;Kaiser and Lamy, 2010) and speleothems (Wang et al, 2001). However, direct terrestrial evidence and chronologies for glacier and ice-sheet response during these periods remain sparse and controversial (see Supplementary Discussion), in part because MIS-4 is beyond the radiocarbon time-scale.…”