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.
Highlights
The last deglaciation, a period of global warming from the end of the Last Glacial Maximum (LGM, ~ 19 kyr BP) to the early Holocene (11.7 kyr BP), is an outstanding period in Earth’s history that allows us a better understanding of the mechanisms regulating regional climatic conditions under global warming (Clark et al, 2012; Shakun et al, 2012)
During the Bølling-Allerød (B-A, 14.7-12.9 kyr BP), a warm period in North Hemisphere, dry conditions developed in TSA (e.g., Mollier-Vogel et al, 2013; Novello et al, 2017; Mulitza et al, 2017) associated with a strong AtlanticMeridional Overturing Circulation (AMOC), a more northerly position of the Intertropical Convergence Zone (ITCZ) and a weakening of the South American Monsoon
EM2 and EM4 modes are interpreted as reflecting local hydrodynamics, while EM3 represents the eolian supply
Summary
The last deglaciation, a period of global warming from the end of the Last Glacial Maximum (LGM, ~ 19 kyr BP) to the early Holocene (11.7 kyr BP), is an outstanding period in Earth’s history that allows us a better understanding of the mechanisms regulating regional climatic conditions under global warming (Clark et al, 2012; Shakun et al, 2012). Meridional Overturing Circulation (AMOC) generated abrupt climatic changes on a millennial-scale (McManus et al, 2004; Mulitza et al, 2017; Ng et al, 2018) The latter resulted in changes in the meridional-oceanic temperature gradient and a meridional shift of the mean annual position of the Intertropical Convergence Zone (ITCZ) (Cheng et al, 2012; Deplazes et al, 2013; Mcgee et al, 2014). Most studies suggest wetter conditions in this region during cold events in North Hemisphere such as Heinrich Stadial 1 (HS1, ~ 18-14.7 kyr BP) and the Younger Dryas (YD, ~ 12.9-11 kyr BP) linked to a southern displacement of the ITCZ (e.g., Mollier-Vogel et al, 2013; Mulitza et al, 2017; Bahr et al, 2018) and an intensification of the South American Monsoon in its southern domain (Novello et al, 2017; Stríkis et al, 2015) in response to the weakening of the AMOC and increased meltwater discharges into the North Atlantic. During the Bølling-Allerød (B-A, 14.7-12.9 kyr BP), a warm period in North Hemisphere, dry conditions developed in TSA (e.g., Mollier-Vogel et al, 2013; Novello et al, 2017; Mulitza et al, 2017) associated with a strong AMOC, a more northerly position of the ITCZ and a weakening of the South American Monsoon
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
