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Changes in sedimentary provenance and climate off the coast of Northeast Brazil since the Last Interglacial
USF St. Petersburg campus Faculty Publications
  • Thiago A. de Sousa, Universidade Federal Fluminense
  • Igor Martins Venancio, Universidade Federal Fluminense
  • Claudio de Morisson Valeriano, Universidade do Estado do Rio de Janeiro
  • Monica Heilbron, Universidade do Estado do Rio de Janeiro
  • Maria T. Weitzel Dias Carneiro, Federal University of Espirito Santo
  • Miguel Angelo Mane, Universidade do Estado do Rio de Janeiro
  • Júlio C. Horta de Almeida, Universidade do Estado do Rio de Janeiro
  • Joseph M. Smoak, University of South Florida St. Petersburg
  • Ana Luiza S. Albuquerque, Universidade Federal Fluminense
  • Emmanoel Vieira Silva-Filho, Universidade Federal Fluminense
Document Type
Article
Publication Date
2021
Abstract

Neodymium (Nd) and strontium (Sr) isotopic signatures in marine sediments reflect the geology of the associated drainage basin from which those sediments are supplied. These signatures are significantly affected by relief, weathering, transport, and deposition of sedimentary contributions from the respective sources. This work makes available new data of Sr–Nd isotope ratios and Rare Earth Element (REE) concentrations, which provides a record of the sedimentary provenance of marine sediment supplied to the continental slope off the coast of northeastern Brazil since the last 130 thousand years. Our results indicate the main source of sediments to this site was the Parnaíba sedimentary basin. Furthermore, the fluctuations in Fe/K, Al/Si ratios, and Sr values are explained by geochemical processes operating within the region, which likely reflects changes in the hydrological regime and relative sea-level, and intensity of weathering in continental rocks in glacial-interglacial timescales. We suggest that low values of 87Sr/86Sr ratios during glacial are a result of dry conditions. Also, minor fluctuations within the last glacial period may be a consequence of displacements of the Intertropical Convergence Zone (ITCZ). Such displacements cause changes in rainfall and consequently variations in chemical weathering which affect Sr isotopic fractionation. During past humid intervals, the low Nd (non-radiogenic) signal observed could be explained as a process of penetration of rainwater into the deepest non-radiogenic sediment and subsequent replacement of the isotopic signal in the environment in glacial-interglacial timescales.

Language
en-US
Citation Information
Thiago A. de Sousa, Igor Martins Venancio, Claudio de Morisson Valeriano, Monica Heilbron, et al.. "Changes in sedimentary provenance and climate off the coast of Northeast Brazil since the Last Interglacial" (2021) ISSN: 00253227
Available at: http://works.bepress.com/joseph-smoak/88/