Geochemistry of upland lacustrine sediments from Serra dos Carajás, Southeastern Amazon, Brazil: Implications for catchment weathering, provenance, and sedimentary processes. (December 2016)

• Record Type: Journal Article
• Authors: Sahoo, Prafulla Kumar; Felix Guimarães, José Tasso; Martins Souza-Filho, Pedro Walfir; Sousa da Silva, Marcio; Maurity, Clovis Wagner; Powell, Mike A.; Rodrigues, Tarcísio Magevski; Fonseca da Silva, Delmo; Mardegan, Sílvia Fernanda; Furtini Neto, Antonio Eduardo; Dall'Agnol, Roberto
• Is Part Of: Journal of South American earth sciences. Volume 72(2016:Dec.)
• Page Start: 178
• Page End: 190
• Publication Date: 2016-12
• Subjects: Lake sediments -- Elemental and isotope geochemistry -- Provenance and weathering -- Sedimentary process -- Serra dos Carajás; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2016.09.003
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: A multi-proxy geochemical study of surficial sediments of an upland lake (Amendoim Lake), located in the Serra dos Carajás region, Brazil, was carried out to understand catchment weathering and provenance of sediments in the basin, as well as sedimentary processes. The carbon and nitrogen isotopic compositions of organic matter in the sediment were quite homogeneous, and suggest that the organic sources for this lake are mainly composed of palms and submerged macrophytes. The R-mode factor analysis indicates that most of the trace elements, including rare earth elements (REEs), are clustered with Al (Group 1), Si is grouped with Zr and Hf (Group 4), total organic carbon (TOC) with TS and Hg (Group 2), and Fe with Mn and As (Group 3). The elements of the Group 1 show strong positive correlations with Al, suggesting that these elements are hosted in detrital minerals during laterization in the catchment basin and not significantly affected by diagenesis. The high CIA values (96–99) of sediments together with their position in A-CN-K and log (Fe2 O3 /K2 O) vs log (SiO2 /Al2 O3 ) plots indicate intense chemical weathering in source area. However, similar geochemical signatures between lake sediments and catchment lateritic crust indicates that mechanical erosion was the dominant sediment formation process. REE patterns normalized to chondrite along with geochemical indices (Al/K, Al/Ti, La/Th, La/Al, Ti/Zr, Zr/Hf, Th/Sc, Co/Th, Ba/Sr, and Eu/Eu*) also indicate that the sediments are mainly derived from laterite crust. This study provides reliable background information to reconstruct weathering processes and lake evolution in the Serra dos Carajás area. Highlights: Factor analysis was used to trace geochemical signatures in sediments. Trace elements and REEs in sediments were controlled by Al-oxides. Geochemical proxies evaluated the effect of weathering and provenances. Sediment geochemistry discriminated the nature of source rock. δ 13 C and δ 15 N proxies evaluated the origin of organic matter in sediments.