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Item type:Publication, Heinrich events and tectonic uplift as possible drivers for late Quaternary fluvial dynamics in the western Peruvian Andes(Elsevier B.V., 2022-11-01)Late Quaternary fluvial valley development in Peru is considered to be driven by summer insolation maxima in the precession cycle, which coincide with increased precipitation and rising lake levels in the central Andes. Our literature review, however, indicates that fluvial aggradation does not always coincide with summer insolation maxima but may also occur during transitions between insolation maxima and minima or even during summer insolation minima. Tectonic uplift as a driver of fluvial incision has not been considered in the current terrace formation models, despite the Peruvian margin being located above an active subduction zone. We present new chronologic, stratigraphic and geomorphic data of the Cañete River valley over the past 102 ± 6 ka. We mapped its fluvial terraces (11.5°-13° southern latitude) along a 75-km long reach perpendicular to the strike of the Andes. Five fluvial terraces and one floodplain level were identified with relative elevations of up to 181.1 m above the floodplain. Thirty-three (pIR) IRSL ages of eight fluvial terraces and one alluvial fan sediment sample showed that their ages in part correspond to summer insolation maxima of the precession cycle, but that a better match exists with pluvial periods that coincided with Heinrich events of the northern hemisphere and rising lake levels in the Andes. The chronology of terraces of the Cañete River agrees with those of previously studied fluvial systems between 7° and 16° southern latitude in Peru, suggesting a regional-scale fluvial response possibly to the Heinrich events. Reconstructed longitudinal profiles and terrace ages were utilised to calculate vertical incision rates. We calculated a mean rate of 1.8 ± 0.10 mm a−1 over the last 102 ± 6 ka, but incision rates varied considerably within this time period possibly in response to changes in the Qs: Qw ratio as a consequence of increased sediment input during the wet Heinrich events. A set of 1338 GNSS measurements of daily, vertical crustal deformation of the years 2009–2015 showed a continuous and positive trend in interseismic, accumulative vertical crustal movements with a time-averaged, crustal uplift rate of 1.9 ± 3.6 mm a−1. The positive trend in vertical movements, together with data from literature suggest landscape rejuvenation along the forearc and western Cordillera in central Peru. It is proposed that maximally ∼0.5 mm a−1 of the total incision over the past 102 ka may possibly be related to nonrecoverable, interseismic deformation. Climate change-driven variations in the Qs:Qw ratio are superimposed on the long-term tectonic uplift trend, and both are considered the main drivers of fluvial incision. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Performance Comparison of SRTM v. 3.0, AW3D30, ASTER GDEM3, Copernicus and TanDEM-X for Tectonogeomorphic Analysis in the South American Andes(Elsevier B.V., 2023-07-01)Digital Elevation Models (DEMs) are widely used to assess the degree of tectonic activity in mountainous landscapes. But hardly ever have quality assessments of DEMs been carried out to assess their suitability for the calculation of the most widely used tectonogeomorphic indices. For that reason, we have analysed the five most commonly used DEMs for two tectonic basins in the Peruvian Andes. Those are the 30-m SRTM v.3.0, AW3D30, ASTER GDEM3, Copernicus and the 12-m TanDEM-X. The analysed indices are related to the characteristics of 22 drainage networks and we included a vertical accuracy assessment based on available GNSS control points. Copernicus produced the smoothest river profiles followed by AW3D30 and TanDEM-X. River profiles from the rainforest-covered Moyobamba tectonic basin were noisier than those from the more arid Huancayo tectonic basin. All DEMs performed statistically similar in the calculation of drainage basin area, θ, m/n, Ksn and the Hypsometric Integral. Copernicus and TanDEM-X generated the longest drainage networks. TanDEM-X showed the highest vertical accuracy with a RMSE of 3.174 m in the rugged Huancayo basin, and 2.172 in the Moyobamba basin, followed by AW3D30. Copernicus showed very uneven results between both tectonic basins. TanDEM-X allowed the most detailed mapping of fluvial and tectonic landforms, with the identification of six out of seven fluvial terraces, while Copernicus performed best of all 30-m DEMs. The overall best performing DEMs were Copernicus and TanDEM-X, closely followed by AW3D30. ASTER GDEM3 generally performed worst. In general, there was more statistical variability between DEMs in the more rugged Huancayo basin, suggesting that steeper slopes had a significant impact on the calculated indices. Our results provide a clear guideline for the scientific community of which DEMs to pick for the calculation of the various tectonogeomorphic indices.