Cooperation among tectonic and surface processes in the St. Elias Range, Earth's highest coastal mountains

Abstract

Investigations of tectonic and surface processes have shown a clear relationship between climate‐influenced erosion and long‐term exhumation of rocks. Numerical models suggest that most orogens are in a transient state, but observational evidence of a spatial shift in mountain building processes due to tectonic‐climate interaction is missing. New thermochronology data synthesized with geophysical and surface process data elucidate the evolving interplay of erosion and tectonics of the colliding Yakutat microplate with North America. Focused deformation and rock exhumation occurred in the apex of the colliding plate corner from > 4 to 2 Ma and shifted southward after the 2.6 Ma climate change. The present exhumation maximum coincides with the largest modern shortening rates, highest concentration of seismicity, and the greatest erosive potential. We infer that the high sedimentation caused rheological modification and the emergence of the southern St. Elias, intercepting orographic precipitation and shifting focused erosion and exhumation to the south.

Which are the highest peaks in the US Arctic? Fodar settles the debate

“…Chamberlin is covered by the largest glacier and also shows signs of the largest changes to its peak. In recent years, many glaciated peaks in Alaska have experienced massive rock/ice avalanching (Molnia and Angeli, 2014), and the destabilizing effect of climate warming on mountain peaks has been noted worldwide (Gruber and Haeberli, 2007;Huggel, 2009;Huggel et al, 2012;Enkelmann et al, 2015). For example, Mt.…”

Evaluation of detrital thermochronology for quantification of glacial catchment denudation and sediment mixing

“…Most studies use thermochronometry on bedrock samples but the use of detrital samples has been shown to be a powerful tool and became increasingly popular (e.g., Enkelmann et al, 2009Enkelmann et al, , 2011Enkelmann et al, , 2015Stock et al, 2006;Rahl et al, 2007;Vermeesch, 2007Vermeesch, , 2013Whipp et al, 2009;Avdeev et al, 2011;Thomson et al, 2013). Although there is a general loss of the spatial information of where the cooling age is sourced within the catchment, there are several advantages that come with dating detrital material: (1) the age distribution of a detrital sample can provide an integrated picture of the cooling age pattern for the entire catchment, (2) using detrital thermochronometry on sedimentary strata of known depositional age allows quantification of changes in either the source rock exhumation rates, or catchment area through time (e.g., Bernet and Garver, 2005;Bernet et al, 2009), and (3) detrital samples can provide age information from regions that may be otherwise inaccessible for bedrock sampling due to thick vegetation cover, lacking infrastructure, political reasons, landscapes that are too steep, or ice coverage.…”

Late Miocene to Pleistocene Source to Sink Record of Exhumation and Sediment Routing in the Gulf of Alaska From Detrital Zircon Fission‐Track and U‐Pb Double Dating

“…The efficient interplay between tectonics and climate‐driven surface processes has built the highest coastal mountain range on earth with up to 5,000 m of local relief (Figure ; Bruhn et al, ; Enkelmann, Koons, et al, ; Enkelmann et al, ; Gulick et al, ; Pavlis et al, ). This impressive landscape is the result of voracious glacial erosion and the effective transport of sediment by tidewater glaciers into the Gulf of Alaska (Enkelmann, Koons, et al, ; Headley et al, ; Jaeger et al, ; Pavlis et al, ; Péwé, ; Spotila et al, ; Falkowski et al, ). Glaciation in the St. Elias Mountains is suggested to have started by ~6–5 Ma (Lagoe et al, ) with sediment mainly deposited on the Yakutat shelf.…”