Date/heure
Date(s) - 21 septembre 2023
13 h 00 min - 14 h 00 min
Catégories
Quantification of Earth Surface Processes in the Eastern Central Andes: Transport Rates on millennial to decadal timescales
Résumé: The eastern Central Andes in northwestern Argentina and southern Bolivia mark the eastern border of the Central Andean Plateau. With an average elevation of about 3.7 km the semi-arid to arid Central Andean Plateau (Altiplano-Puna) constitutes the world’s second largest orogenic plateau. The internally-drained region is characterized by compressional basin-and-range topography. A transsect from the eastern low-elevation foreland areas to the Central Andes in the west shows a distinctive barrier with steep gradients in topography, climate, and ecology. The cordilleras in the transition zone from east to west are actively deformed and are exposed to the South-American Monsoon System.
This environment provides unique opportunities to understand and describe rates of transport processes on the Earth’s surface. On millennial to centennial timescales, we rely on cosmogenic nuclides to quantify rates and show their differences between dry and wet areas. At decadal time scales, we use remote-sensing observations from radar and optical wavelengths to identify and measure change. We suggest new data-driven approaches relying on radarinterferometric coherence and UAV observations to measure areas of active erosion that go beyond landscape steepness analyses. We demonstrate the complexity of Earth Surface Processes and show that long-term rates are dictated by tectonic preconditioning and deformation gradients, but shorter-timescale fluctuations are guided by climate-driven processes. Late Pleistocene climate variations and associated processes have increased landslide frequency and triggered glacial advances – both signals are visible in present-day records and will be explored during this presentation.