Late Quaternary drainage dynamics in northern Brazil based on the study of a large paleochannel from southwestern Marajó Island

Abstract

Marajó Island shows an abundance of paleochannels easily mapped in its eastern portion, where vegetation consists mostly of savannas. SRTM data make possible to recognize paleochannels also in western Marajó, even considering the dense forest cover. A well preserved paleodrainage network from the adjacency of the town of Breves (southwestern Marajó Island) was investigated in this work combining remote sensing and sedimentological studies. The palimpsest drainage system consists of a large meander connected to narrower tributaries. Sedimentological studies revealed mostly sharp-based, fining upward sands for the channelized features, and interbedded muds and sands for floodplain areas. The sedimentary structures and facies successions are in perfect agreement with deposition in channelized and floodplain environments, as suggested by remote sensing mapping. The present study shows that this paleodrainage was abandoned during Late Pleistocene, slightly earlier than the Holocene paleochannel systems from the east part of the island. Integration of previous studies with the data available herein supports a tectonic origin, related to the opening of the Pará River along fault lineaments. This would explain the disappearance of large, north to northeastward migrating channel systems in southwestern Marajó Island, which were replaced by the much narrower, south to southeastward flowing modern channels.

Erosion of an active fault scarp leads to drainage capture in the Amazon region, Brazil

“…An increasing number of studies in the Amazon River basin reveal remarkable evidence of landscape changes over scales of hundreds of square kilometers (Rossetti and Góes, ; Mantelli et al ., ; Hayakawa et al ., ). In Central Amazonia, several studies suggest that such changes are driven by Quaternary tectonism (Franzinelli and Igreja, ; Rossetti et al ., ; Almeida‐Filho and Miranda, ; Silva et al ., ), but stop short in constraining timing of deformation and its connection to landscape change.…”

The role of tectonics in the late Quaternary evolution of Brazil's Amazonian landscape

“…11C) attributed to a Late Pleistocene drainage network(Rossetti and Góes, 2008). Northwestward channels converge into the Melgaço−Portel Bay, which is itself attached to the Pacajaí−Caxiuanã Bay to the west through a single, narrow and also NW− trending channel.…”

Analyzing the Impacts of Frequency and Severity of Forest Fire on the Recovery of Disturbed Forest using Landsat Time Series and EO-1 Hyperion in the Southern Brazilian Amazon

“…Feições morfológicas relacionadas a paleocanais são presentes na área de estudo, embora em volume inferior ao verificado em outras áreas da Ilha do Marajó, como relatado em trabalhos prévios Rossetti & Góes 2008;Rossetti et al 2008). Estes são, em geral, contínuos, mas também ocorrem paleocanais representados por segmentos isolados, cuja continuidade lateral pode ser facilmente reconstituída dada sua distribuição espacial (Figura 14).…”