Terraces and river incision in great passive margin escarpments: genetic and geochronological aspects

Terrazas y incisión fluvial en grandes escarpes de margen pasivo: aspectos genéticos y geocronológicos

Abstract

Fluvial terraces and their depositional tracts are important geoindicators of past environmental conditions and the relief neoquaternary evolution, and in regions of great escarpments passive margins assume different genetic links. This article aims to discuss different causes generate these geoforms, using techniques of faciologic and geochronological analysis and paying attention to general patterns of occurrence and distribution, as well as to particularities, articulating regional characteristics and local controls. For this purpose, dating by Optically Stimulated Luminescence (OSL) and facies analyzes on nine river terraces, integrated with other chronological results, obtaining ages between the terminal Pleistocene and the Holocene. As for genetic links, terraces generated by river capture, transposition of thresholds and vertical notch by tectonic uplift were found, results that expand the knowledge about the sedimentary organization in the great escarpments domain, allowing the correlation with other regional studies.

Keywords:
Fluvial depositional levels; Fluvial captures; Vertical notch; Neotectonic control; Optically Stimulated Luminescence