Preprints
https://doi.org/10.5194/cp-2021-183
https://doi.org/10.5194/cp-2021-183

  07 Jan 2022

07 Jan 2022

Review status: this preprint is currently under review for the journal CP.

Millennial variability of terrigenous transport to the central-southern Peruvian margin during the last deglaciation (18–13 kyr BP)

Marco Yseki1, Bruno Turcq1, Sandrine Caquineau1, Renato Salvatteci2, José Solis3, C. Gregory Skilbeck4, and Dimitri Gutiérrez3,5 Marco Yseki et al.
  • 1LOCEAN-IPSL, Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques, Sorbonne Université, CNRS, IRD, MNHN, Paris, France
  • 2Center for Ocean and Society, Kiel University, Kiel, 24105, Germany
  • 3Laboratorio de Ciencias del Mar, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
  • 4Faculty of Science, University of Technology Sydney. PO Box 123 Broadway, Sydney NSW. 2007
  • 5Dirección General de Investigaciones Oceanográficas y de Cambio Climático, Instituto del Mar del Perú, Callao. Peru

Abstract. Reconstructing precipitation and wind from the geological record could help to understand the potential changes in precipitation and wind dynamics in response to climate change in Peru. The last deglaciation offers natural experimental conditions to test precipitation and wind dynamics response to high latitude forcing. While considerable research has been done to reconstruct precipitation variability during the last deglaciation in the Atlantic sector of South America, the Pacific sector of South America has received little attention. This work aims to fill this gap by reconstructing types of terrigenous transport to the central-southern Peruvian margin (12° S and 14º S) during the last deglaciation (18–13 kyr BP). For this purpose, we used grain-size distribution in sediments of marine core M77/2-005-3 (Callao, 12º S) and G14 (Pisco, 14º S). We analyzed end-members (EM) to identify grain-size components and reconstruct potential sources and transport processes of terrigenous material across time. We identified four end-members for both Callao and Pisco sediments. In Callao, we propose that changes in EM4 (101 μm) and EM2 (58 μm) contribution mainly reflect hydrodynamic energy and diffuse sources, respectively, while EM3 (77 um) and EM1 (11 μm) variations reflect changes in aeolian and fluvial inputs, respectively. In Pisco, changes in the contribution of EM1 (10 μm) reflect changes in river inputs while EM2 (52 μm), EM3 (75 μm) and EM4 (94 μm) reflect an aeolian origin linked to surface winds. At millennial-scale, our record shows an increase of the fluvial inputs during the last part of Heinrich Stadial 1 (~ 16–14.7 kyr BP) at both locations. This increase was linked to higher precipitation in Andes related to a reduction of the Atlantic Meridional Overturning Circulation and meltwater discharge in North Atlantic. In contrast, during Bølling-Allerød (~ 14.7–13 kyr BP), there was an aeolian input increase, associated with stronger winds and lower precipitation that indicate an expansion of the South Pacific Subtropical High. These conditions would correspond to a northern displacement of the Intertropical Convergence Zone-South Subtropical High system associated with a stronger Walker circulation. Our results suggest that variations in river discharge and changes in surface wind intensity in the western margin of South America during the last deglaciation were sensitive to Atlantic Meridional Overturning Circulation variations and Walker circulation on millennial timescales. In the context of global warming, large-scale precipitation and fluvial discharge increases in the Andes related to Atlantic Meridional Overturning Circulation decline and southward displacement of the Intertropical Convergence Zone should be considered.

Marco Yseki et al.

Status: open (until 04 Mar 2022)

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Marco Yseki et al.

Marco Yseki et al.

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Short summary
In the present work we reconstruct changes in river discharge and wind in Peru during the last deglaciation to understand the mechanisms that modulate changes in precipitation and winds during a period of global warming. We found that changes in river discharge and wind intensity in Peru were sensitive to high-latitude forcing (changes in the intensity of Atlantic Meridional Overturning Circulation) and Walker circulation variations on millennial timescales respectively.