Analysis of tectonic-controlled fluvial morphology and sedimentary processes of the western Amazon Basin: an approach using satellite images and digital elevation model

Clauzionor L Silva,Norberto Morales,Jairo R Jiménez-Rueda,Alvaro P Crósta,Solange S Costa

doi:10.1590/s0001-37652007000400010

Abstract

An investigation of the tectonic controls of the fluvial morphology and sedimentary processes of an area located southwest of Manaus in the Amazon Basin was conducted using orbital remote sensing data. In this region, low topographic gradients represent a major obstacle for morphotectonic analysis using conventional methods. The use of remote sensing data can contribute significantly to overcome this limitation. In this instance, remote sensing data comprised digital elevation model (DEM) acquired by the Shuttle Radar Topographic Mission (SRTM) and Landsat Thematic Mapper images. Advanced image processing techniques were employed for enhancing the topographic textures and providing a three-dimensional visualization, hence allowing interpretation of the morphotectonic elements. This led to the recognition of main tectonic compartments and several morphostructural features and landforms related to the neotectonic evolution of this portion of the Amazon Basin. Features such as fault scarps, anomalous drainage patterns, aligned ridges, spurs and valleys, are expressed in the enhanced images as conspicuous lineaments along NE-SW, NW-SE, E-W and N-S directions. These features are associated to the geometry of alternated horst and graben structures, the latter filled by recent sedimentary units. Morphotectonic interpretation using this approach has proven to be efficient and permitted to recognize new tectonic features that were named Asymmetric Ariaú Graben, Rombohedral Manacapuru Basin and Castanho-Mamori Graben.

Highlights

The use of thematic maps, such as landscape, drainage, hypsometric, morphometric and geomorphologic maps, constitutes the basis of morphotectonic analysis, for investigating Cenozoic tectonics
Important structural features, such as tectonically uplifted and lowered areas, fault scarps, aligned ridges and spurs, and anomalous patterns in the drainage, were determined. Such features were used to interpret the morphotectonic framework of the study area and to compare it to the regional neotectonic model proposed by Hasui (1990) and Costa and Hasui (1997)
The main tectonic compartments of the western Amazon Basin near Manaus were interpreted by means of morphotectonic analysis, supported by orbital InSAR (SRTM) and optical (Landsat ETM+) images and field

Summary

INTRODUCTION

The use of thematic maps, such as landscape, drainage, hypsometric, morphometric and geomorphologic maps, constitutes the basis of morphotectonic analysis, for investigating Cenozoic tectonics. A new remote sensing technology based on radar interferometry (InSAR) is making it possible to acquire high quality altimetric data (Madsen and Zebker 1998) Using this technology, NASA launched the Shuttle Radar Topography Mission (SRTM) in 2000, which allowed the acquisition of altimetric data and the generation of DEMs of nearly 80% of the Earth’s surface (Rabus et al 2003). Analyses of the drainage network, landscape features and geological information were spatially integrated to support the morphostructural interpretation, the field checking of structural features and the spatial analysis of the Cenozoic cover Important structural features, such as tectonically uplifted and lowered areas, fault scarps, aligned ridges and spurs, and anomalous patterns in the drainage, were determined. Such features were used to interpret the morphotectonic framework of the study area and to compare it to the regional neotectonic model proposed by Hasui (1990) and Costa and Hasui (1997)

MATERIALS AND METHODS

Findings

CONCLUSIONS