Climate and hydrologic controls on late Holocene sediment supply to an Amazon floodplain lake
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ORIGINAL PAPER
Climate and hydrologic controls on late Holocene sediment supply to an Amazon floodplain lake Luciane Silva Moreira . Patricia Moreira-Turcq . Renato Campello Cordeiro . Bruno Turcq . Keila Cristina Aniceto . Manuel Moreira-Ramı´rez . Anna Paula Soares Cruz . Sandrine Caquineau . Vanessa Cunha Silva
Received: 21 October 2019 / Accepted: 21 July 2020 Ó Springer Nature B.V. 2020
Abstract Organic and inorganic geochemical analyses on sediments from Preto Lake, a central Amazon basin floodplain water body, were used to document hydrological changes of the Solimo˜es River during the late Holocene. Between 3600 and 400 cal yr BP, Preto Lake received smectite-rich sediment from the Solimo˜es River, with high concentrations of Al (* 53 9 103 ppm) and Si (* 210 9 103 ppm). The high detrital input suggests there was a direct connection between Preto Lake and the main river channel.
High river inflow maintained lake stage and was responsible for the contribution to sediments of phytoplankton-derived organic matter. Low sediment organic carbon concentrations characterized this period (mean * 3.8 wt%), probably because of dilution by river-borne lithogenic matter. Although the river inputs remained high, abrupt increases in TOC content around 1800 and 1200 cal yr BP suggest brief increases in fluvial nutrient supply to Preto Lake. During the last 400 cal yr, substantial declines in
L. S. Moreira (&) R. C. Cordeiro M. MoreiraRamı´rez Departamento de Geoquı´mica, Programa de Po´sGraduac¸a˜o em Geocieˆncias, Universidade Federal Fluminense (UFF), Nitero´i, Brazil e-mail: [email protected]
S. Caquineau e-mail: [email protected]
R. C. Cordeiro e-mail: [email protected] M. Moreira-Ramı´rez e-mail: [email protected] P. Moreira-Turcq Institut de Recherche pour De´veloppement (IRD)-GET (Ge´osciences Environment Toulouse), Bondy, France e-mail: [email protected]
K. C. Aniceto V. C. Silva Programa de Po´s-Graduac¸a˜o em Geocieˆncias da Universidade Federal do Amazonas, Manaus, Brazil e-mail: [email protected] V. C. Silva e-mail: [email protected] A. P. S. Cruz Department of Geological Sciences, California State University, 9001 Stockdale Highway, Bakersfield, CA 93311-1022, USA e-mail: [email protected]
B. Turcq S. Caquineau Institut de Recherche pour De´veloppement (IRD)LOCEAN (Laboratoire d’Oce´anographie et du Climat), Bondy, France e-mail: [email protected]
123
J Paleolimnol
smectite (mean 40%), Al (* 29 9 103 ppm) and Si (138 9 103 ppm) suggest the establishment of a semiisolated lake, with reduced river inflow. A large proportion of C3-plant-derived organic matter, supplied by runoff from the kaolinite-rich watershed, was observed during this period, and was accompanied by high autochthonous primary production, driven by development of an aquatic macrophyte community. This change in sediment organic matter source accounted for the greater TOC content (* 20%) of sediments deposited during this period. Although Holoce
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