Shallow architecture of Fuegian Andes lineaments based on Electrical Resistivity Tomography (ERT). Evidences of transverse extensional faulting in the central Beagle Channel area

Abstract

ABSTRACT. The southern foothills of the Fuegian Andes are bounded by the Beagle Channel (BC), a conspicuous E-W longitudinal basin, controlled by a large transcurrent fault system, which extends from the Atlantic to the Pacific Ocean. The northern shore of the Beagle Channel's central segment is characterized by several E-W oriented valleys, parallel to the main basin, which are interspersed with a series of oblique NW trending lineaments that extend across the mountain belt. A geoelectrical survey was carried out in order to investigate the shallow architecture of such sets of linear morphologies. The principal E-W lineament system was characterized by conspicuous sub-vertical resistivity contrasts, interpreted as fractured zones associated with fault strands of the main strike-slip Beagle Channel system, whereas the oblique NW-SE trending set of lineaments revealed slightly different resistivity patterns, with vertical displacements and less abrupt contrasts. These resistivity patterns, in combination with the widespread occurrence of normal faulting in the area, allowed to infer an extensional control over the oblique depressions. These morphological features were related to oblique transverse faults that segment two sub parallel E-W fault systems. The oblique faults were probably developed along inherited structural anisotropies and can be extended well beyond the BC shoreline to the NW. Both geophysical and field evidence suggest a post-glacial deformation along the area. RESUMEN. Arquitectura somera de lineamientos en los Andes Fueguinos basada en estudios de Tomografía de Resistividad Eléctrica (TER). Evidencias de fallamiento transverso extensional en el área central del canal deBeagle. La cordillera Fueguina está limitada al sur por el canal de Beagle, una gran fosa longitudinal que se extiende desde el océano Atlántico al este, hasta el Pacífico al oeste y está desarrollada sobre un sistema de fallamiento regional transcurrente. La costa norte del segmento central del Canal está caracterizada por la intersección de valles paralelos a la fosa principal con una serie de lineamientos morfológicos oblicuos de orientación NW-SE, los cuales se extienden a través del sistema montañoso. Se llevó a cabo un relevamiento de Tomografía de Resistividad Eléctrica con el objetivo de investigar la arquitectura somera de los diferentes juegos de lineamientos observados en el sector y dilucidar el control estructural que determina su geometría. Los resultados muestran que el sistema de lineamientos E-W está caracterizado por un patrón de resistividades con marcados contrastes de disposición subvertical interpretadas como

Post‐Last Glacial Maximum evolution of a “fjord‐type” lake based on high‐resolution seismic data: the Lago Roca/Acigami (southern Tierra del Fuego, Argentina/Chile)

“…However, this remains highly speculative since there is no substantial field work supporting such a tectonic uplift rate. On the contrary, evidence points to a transtensional/extensional scenario in the area (Bran et al ., ). Therefore, we suggest that glacio‐isostatic adjustment following deglaciation (Ivins and James, ) together with local tectonic subsidence should represent the key factors forcing the RSL changes in the Beagle Channel central sector.…”

“…The Lago Acigami lake basin lies along a northwest-southeast trending tectonic lineament (Tassone et al, 2005;Bran et al, 2017) of the southern slope of the Fuegian Andes (Fig. 1A).…”

Characterization of Sobradinho landslide in fluvial valley using MASW and ERT methods

“…For example, the Electrical Resistivity Tomography (ERT) and the Multi-channel Analysis of Surface Waves (MASW) (which were adopted in this study) are based on the electrical and seismic properties of materials, respectively. ERT has been extensively used for the determination of landslide slip surface and its hydrological characteristics (Kneisel, 2006;Panek et al, 2008;Burda et al, 2013;Dostál et al, 2014;Szalai et al, 2014;Ling et al, 2016;Bran et al, 2017;Kristyanto et al, 2017;Qiao et al, 2017;Carlini et al, 2018;Mita et al, 2018;Kasprzak et al, 2019).…”

Morphometry and spatial distribution of glacial cirques in the Western Fuegian Andes of Argentina, southernmost South America

“…This deformation produced the pervasive strikeslip faulting present through the basement domain (Cunningham, 1994;Ghiglione and Cristallini, 2007) and is responsible for the exhumation of the Cordillera Darwin metamorphic complex (Nelson, 1982;Kohn et al, 1995). The northern shore of the Beagle Channel's central segment is characterized by several E-W oriented glacial valleys, parallel to the channel, which are interspersed with a series of oblique NW-SE trending lineaments that extend across the mountain belt (Bran et al, 2018) (Fig. 2).…”

“…2). The northern portion is composed almost entirely of intensely deformed marine volcanic and sedimentary rocks (schists, carbonaceous slates, sandstones, tuffs, breccias, rhyolite and basalts) of Upper Jurassic age (the Lemaire Formation; Borrello, 1969), whereas the flanks facing south are formed by strongly folded marine meta-sedimentary rocks (dark slates, tuffs, and sandstones) of Lower Cretaceous age (the Yahgan Formation; Kranck, 1932). In the SW part, covering a smaller area, accretion prisms schists (phyllites and amphibolites) of Upper Palaeozoic age emerge (the Lapataia Formation; Caminos et al, 1981).…”