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Lacustrine and marine archives of environmental variability across South America
DDC:
550 - Earth sciences
Abstract:
The ultra-high sedimentation rates at ODP Site 1233, situated at 41°S off Chile, enabled the investigation of the millennial to multi-centennial scale relationship and variability of the Patagonian Ice Sheet (PIS) extent, as indicated by the Fe relative concentration record, and offshore sea surface temperatures (SST) during the last glacial period. The close relationship of the Fe record and the SST pattern as described previously for the 50–19 kyr time-interval extends in the older part of the records (70–50 kyr). During marine isotope stage (MIS) 4, a delay of ~500 yr of PIS retreats relative to SST increases has been found, similar to that described for the coldest part of MIS 3 and 2. During early MIS 3 (~60–56 kyr), synchronous variability in both records resembles the deglacial-to-Holocene time-interval, reflecting either a meltwater pulse or a dominant control of the Fe input by rainfall changes related to a rather small PIS. Results of spectral analysis on the detrended records show three main periodicity-bands at ~4.5–3.1, 2.4–2.2 and 1.2–0.8 kyr. The possible origins of these bands are discussed in terms of stochastic resonance and solar forcing.
