Environmental variability at the margin of the South American Monsoon System recorded by a high-resolution sediment record from Lagoa Dourada (South Brazil)

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Authors

Bernd Zolitschka , An-Sheng Lee , Daniela Piraquive Bermúdez , Thomas Giesecke 

Abstract

High-resolution geochemical and sedimentological data have been obtained for a lacustrine sediment record from Lagoa Dourada (South Brazil). Four distinctly different depositional processes were determined: (1) Suspension fallout of fine-grained minerogenic particles transferred via fluvial activity dominates the Early Holocene and relates to open grassland in the catchment area; (2) Activation of the karst hydrological system with deposition of massive sand layers indicates increased precipitation at the onset of the Middle Holocene; (3) Minerogenic sediments are replaced by organic deposition due to wetter climatic conditions with the expansion of woodlands in combination with release of dissolved nutrients due to enhanced pedogenesis during the Middle to Late Holocene; (4) Human-induced land-use change caused destabilization of soils in the catchment area with resulting cultural soil erosion between AD 1800 and 1950. These depositional trends are linked to intensity variations of the South American Monsoon System (SAMS). Century-long climatic events detected by data of high-resolution XRF scanning confirm this relationship and provide signals of the 8.2 and 4.2 ka events as well as of the Little Ice Age. These events document increased rainfall with complex responses of the environmental system. Our SAMS-induced consequences of past hydroclimatic variability on the environment of South Brazil provide background information for better evaluating model projections of future climate change.

DOI

https://doi.org/10.31223/X5391T

Subjects

Earth Sciences, Geochemistry, Geomorphology, Sedimentology

Keywords

geochemistry, hydroclimate, soil erosion, Holocene, Little Ice Age, human impact, XRF scanning, 8.2 ka event, Little Ice Age (LIA), South American Monsoon System (SAMS)

Dates

Published: 2021-06-25 12:43

Last Updated: 2021-09-06 10:17

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
Additional datasets for this study are available as supplementary Figures S1 to S6 and as Table S1. The multiproxy dataset of the lacustrine sediment record from Lagoa Dourada will be accessible via the PANGAEA data archiving and publication system and will be provided in due time latest during revision.

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