Tectonic control of erosion in the southern Central Andes

Detrital Thermochronology Reveals Major Middle Miocene Exhumation of the Eastern Flank ofthe Andes That Predates the PampeanFlat Slab (33°–33.5°S)

“…Our data definitively demonstrate the continuity of exhumation across the flat slab transition with the additional constraint of AFT track lengths that indicate rapid cooling initiated at circa 16 Ma and agree with independent geological evidence (Buelow et al, 2018;Pinto et al, 2018;Porras et al, 2016). The estimated lag time-derived average exhumation rate from~16 Ma to recent (~200-275 m/Myr) is consistent with tectonically active orogens (for which rates may vary between 100-1,000 m/Myr; e.g., Burbank, 2002;Montgomery & Brandon, 2002) and is comparable to that obtained by Riesner et al (2019) for Cordón del Portillo using an AHe vertical sampling profile, as well as decadal and millennial scale erosion rates for the Frontal Cordillera (Carretier et al, 2013;Pepin et al, 2013;Val et al, 2018) over the same range of latitudes.…”

The Case for Tectonic Control on Erosional Exhumation on the Tropical Northern Andes Based on Thermochronology Data

“…cosmogenic radionuclides (e.g., Godard et al, 2014;Scherler et al, 2014;Val et al, 2018) and thermochronology data (e.g., Bermúdez et al, 2013;Fitzgerald et al, 1999;Schildgen et al, 2007) as well as numerical models (Godard et al, 2006;Roe & Brandon, 2011), have shown a strong correlation between exhumation rates and tectonic variables. Tectonics, expressed as rock and/or surface uplift, increases a landscape's relief, and consequently the steepness of fluvial channels, resulting in increased exhumation rates (e.g., Kirby & Whipple, 2012).…”

Contrasting Impacts of a Hotter and Drier Future on Streamflow and Catchment Scale Sediment Flux in the High Andes

“…Annual precipitation also exhibits significant interannual variability on either side of the range, with higher annual precipitation associated with El Niño events and lower annual precipitation associated with La Niña (Bozkurt et al, 2018;Cortés et al, 2011;Masiokas et al, 2006). Previous estimates of catchment-averaged erosion rates in the high Andes approach 0.30 mm/a and are identical within uncertainty using either 10 Be or stream gauge data (Carretier et al, 2013;Val et al, 2018). Erosion rates reflect tectonic processes within the region and are highest between 33° and 34°S (Val et al, 2018).…”

“…Black lines across vertical bars represent median erosion rates for each scenario depicted. Erosion rates calculated using observed stream gauge data from this and other studies along with 10 Be results from other studies(Carretier et al, 2013;Val et al, 2018) are shown for comparison to the baseline period scenarios. Note different y-axis limits for the Río Choapa, the northernmost catchment in this study, which also has the lowest observed erosion rates.…”