Peru margin palaeoceanography since the Last Glacial Maximum and the long-term implications for El Niño-Southern Oscillation
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Date
2012-08-05
Journal Title
Journal ISSN
Volume Title
Publisher
Australian Geosciences Council
Abstract
Laminated-sediment cores from nine shelf sites along the Peru continental margin between 11◦S and 14.5◦S, reveal a 20,000 yr inter-millennial scale pattern of sediment accumulation consistent with other
equatorial and south Pacific-rim indicators of long-term ENSO behaviour. Nearly 200 carbon-14 dates define 6 distinct periods during the Holocene-LGM each characterised by linear sedimentation rates that can be regionally correlated between the cores. The early (∼10–8.5 cal Kyr BP) and late (∼2.5–0cal Kyr BP) Holocene, and early Deglaciation (15.5–20Kyr BP) were periods of relatively rapid accumulation (∼80 and 100+ cm/ka), with thin, rapidly deposited laminae, whereas from ∼4.5 to ∼2.5 cal Kyr BP sediments accumulated at ∼20 cm/ka. The middle Holocene (∼8.5 to 4.5 cal Kyr BP) was characterised by very slow sediment deposition, erosion and slumping. The latter period corresponds
with the mid Holocene minima in March-September equatorial insolation. Sedimentation data are supplemented by 2 mm-spaced scanning XRF records that confirm the significance of the millennial-scale associations and support a long-term ENSO-like (alternating flooding and drought from continental south America) interpretation. We suggest that this regional pattern indicates millennial changes in nearshore ocean currents with the middle Holocene representing a period of intensified upwelling.
Description
Keywords
Peru, Pleistocene epoch, Southern Oscillation, Carbon 14, Sediments, Geologic deposits, Erosion, Floods, X-ray fluorescence analysis, Upwelling
Citation
Skilbeck, G., Gutierrez, D., Rein, B., Sifeddine, A., Salvattechi, R., Fink, D., Druffel, E., Sanchez-Cabeza, J.-A., Morgenstern, W., Murray, B., & Dunbar, R. (2012). Peru margin palaeoceanography since the Last Glacial Maximum and the long-term implications for El Niño-Southern Oscillation. Paper presented to the 34th International Geological Congress 2012, "Unearthing our Past and Future - Resourcing Tomorrow". 5-10 August 2012 . Brisbane, Australia. (pp. 704).