Preprint Review Version 1 This version is not peer-reviewed

Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems – New Perspectives Using the SISAL Database

Version 1 : Received: 4 October 2018 / Approved: 5 October 2018 / Online: 5 October 2018 (09:43:08 CEST)

How to cite: Deininger, M.; Ward, B.M.; Novello, V.F.; Cruz, F.W. Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems – New Perspectives Using the SISAL Database. Preprints 2018, 2018100094 (doi: 10.20944/preprints201810.0094.v1). Deininger, M.; Ward, B.M.; Novello, V.F.; Cruz, F.W. Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems – New Perspectives Using the SISAL Database. Preprints 2018, 2018100094 (doi: 10.20944/preprints201810.0094.v1).

Abstract

Here we present an overview of speleothem δ18O records from South America, which mostly are available in the Speleothem Isotopes Synthesis and Analysis (SISAL_v1) database. South American tropical and subtropical δ18O time series are primarily interpreted as being driven by the amount effect and, consequently show the past history of the convection intensity of convergence zones such as the Intertropical Convergence Zone and the South America Monsoon System. We investigate past hydroclimate scenarios in South America related to the South American Monsoon System in three different time scales: Late Pleistocene, Holocene and the last two millennia. The precession driven insolation is the main driver of convective variability over the continent during the last 250 kyrs, including the Holocene period. However a dipole is observed between the west and east portions of the continent. Records located in the central region of Brazil appear to be weakly affected by insolation driven variability and more susceptible to the South Atlantic Convergence Zone. Cold episodic events in Northern Hemisphere increase the activity of the South American Monsoon System on all time scales, in turn increasing rainfall amounts in South America, as was documented during Heinrich events in the late Pleistocene and Bond events in the Holocene, as well as during the Little Ice Age.

Subject Areas

South American Monsoon System 1; SAMS 2; SISAL 3; speleothems 4; Quaternary 5

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