DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Item Tectonic control of erosion in the southern Central Andes.(2018) Val, Pedro Fonseca de Almeida e; Venerdini, Agostina L.; Ouimet, William; Alvarado, Patricia; Hoke, Gregory D.Landscape evolution modeling and global compilations of exhumation data indicate that a wetter climate, mainly through orographic rainfall, can govern the spatial distribution of erosion rates and crustal strain across an orogenic wedge. However, detecting this link is not straightforward since these relationships can be modulated by tectonic forcing and/or obscured by heavy-tailed frequencies of catchment discharge. This study combines new and published along-strike average rates of catchment erosion constrained by 10Be and river-gauge data in the Central Andes between 28◦S and 36◦S. These data reveal a nearly identical latitudinal pattern in erosion rates on both sides of the range, reaching a maximum of 0.27 mm/a near 34◦S. Collectively, data on topographic and fluvial relief, variability of rainfall and discharge, and crustal seismicity suggest that the along-strike pattern of erosion rates in the southern Central Andes is largely independent of climate, but closely relates to the N–S distribution of shallow crustal seismicity and diachronous surface uplift. The consistently high erosion rates on either side of the orogen near 34◦S imply that climate plays a secondary role in the mass flux through an orogenic wedge where the perturbation to base level is similar on both sides.Item Regional landscape response to thrust belt dynamics : the Iglesia basin, Argentina.(2018) Ruetenik, Gregory A.; Hoke, Gregory D.; Moucha, Robert; Val, Pedro Fonseca de Almeida eIntermontane basins are often the result of regionally variable uplift in tectonic settings. Wedge-top basins, a type of intermontane basin, form along thrust faults within a fold and thrust belt, and provide an ideal environment to study the regional fluvial and surface response to local variations in rock uplift. This study simulates the formation and evolution of an intermontane basin using a landscape evolution model. The modelling results demonstrate that large trunk streams maintain connectivity during basin formation for two reasons: (1) their stream power is enhanced by the capture of smaller streams, enabling them to incise through the uplifting downstream region, and (2) they acquire increased sediment yield to completely infill the upstream accommodation space rather than forming an endorhic basin. During active deformation of the fold-and-thrust belt, both channel slope and erosion rates are reduced upstream of the intermontane basin and these changes propagate as a wave of low erosion into the uplands. For a uniform background uplift rate in a landscape previously at steady state, this reduced rate of erosion results in a net surface uplift upstream of the basin. Following the eventual breach of the basin’s bounding structural barrier, a wave of high erosion propagates through the basin and increases the channel slope. This onset of increased erosion can be delayed by up to several million years relative to the onset of downstream uplift. Observed paleoerosion rates in paired wedge-top and foreland basin sequences, and presentday stream profiles in the Argentine Precordillera support our modelling results. Our results may be extrapolated to other foreland systems, and are potentially identifed using low-temperature thermochronometers in addition to paleoerosion rates.