An integrated analysis of palynofacies and diatoms in the Jucurucu River valley, northeastern Brazil: Holocene paleoenvironmental changes

Author(s)

Lorente, Flavio Lima ; Castro, Darcilea Ferreira ; Francisquini, Mariah Izar ; Ruiz Pessenda, Luiz Carlos ; Fontes, Neuza Araujo ; Lisboa Cohen, Marcelo Cancela ; Bendassolli, Jose Albertino ; Piccolo, Marisa de Cassia ; Macario, Kita

• Document type: Journal article
• Source: Journal of South American Earth Sciences; v. 103, p. 11-pg., 2020-11-01.

Abstract

This study demonstrates the usefulness of palynofacies as a tool for characterizing the origin, transport, and settling of particulate organic matter preserved in fluvial plain sediments and its integration with diatoms for inferring past depositional environments. Palynofacies, diatoms, and organic geochemistry (S, C/S) data from a sediment core (PR07) collected from the Jucurucu River valley in coastal southern Bahia, northeastern Brazil were used to better understand ecosystem changes that occurred in the region during the last similar to 7.5k years. Elemental values (S: 0.15-5.9%; C/S: 0.12-41.5) suggest marine and fluvial influences in the valley during the Holocene, and organic matter was derived from freshwater and marine phytoplankton. The presence of heterolithic deposits, brackish/marine diatoms, predominance of amorphous group, non-opaque phytoclasts, pyrite crystals, and marine microfossils suggests that a tidal flat formed during a mid-Holocene sea-level highstand. A fluvial plain developed in the last 5k years, due to marine regression and an increase in fluvial sediment supply to the region. (AU)

• FAPESP's process: 11/00995-7 - Interdisciplinary paleoenvironmental studies in the Espirito Santo State coast
• Grantee: Luiz Carlos Ruiz Pessenda
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 15/05111-0 - Palaeoenvironmental reconstitution (relative sea level, vegetation and climate) of the south coast of Bahia based on biological and isotopic indicators
• Grantee: Flávio Lima Lorente
• Support Opportunities: Scholarships in Brazil - Post-Doctoral