Rapid exhumation in the Western Alps driven by slab detachment and glacial erosion

Abstract

Inverse ApproachOur method to convert thermochronometric ages to exhumation rates combines a thermal model, to predict temperature, with a closure temperature calculation for each thermochronometric system (Fox et al., 2014). A thermal model is used to predict temperature in space and time, as well as a material-point cooling rate, from which we calculate the characteristic closure temperature and its depth. The exhumation rate or, equivalently, the surface erosion rate at this point in space is a function of time, and is related to the age, , through a travel-time expression,

3-D GPS velocity field and its implications on the present-day post-orogenic deformation of the Western Alps and Pyrenees

“…This suggests a wedge of softer material in the lower crust below the Alps , in some way similar to the Andes of Patagonia where a localized uplift due to glacier mass changes is modeled based on a wedge of softer material in the continental lithosphere (Klemann et al, 2007). This does not exclude contributions from deep processes for part of the uplift (Fox et al, 2015) or erosion-induced rebound (Champagnac et al, 2007;Genti et al, 2015;Vernant et al, 2013). A careful and detailed model of the response to the Last Glacial Maximum of the Pyrenees and the Alps will certainly bring valuable new insights on post-orogenic mountain processes.…”

“…Can tectonic velocities, likely below 1 mm yr −1 , be resolved for the Western Alps and the Pyrenees mountains? Can uplift patterns in these two mountain belts help constrain studies of ongoing tectonics and dynamics (e.g, Champagnac et al, 2007;Fox et al, 2015;Genti et al, 2015;Vernant et al, 2013)?…”

Deciphering neotectonics from river profile analysis in the karst Jura Mountains (northern Alpine foreland)

“…Fox et al 2015). In this framework, numerous studies focused on river morphology to quantify the interplay between tectonics and fluvial erosion (e.g., Jackson et al 1996;Demoulin 1998;Snyder et al 2000;Kirby and Whipple 2001;Whipple 2004;Wobus et al 2006;Sougnez and Vanacker 2010;Castelltort et al 2012;Walsh et al 2012).…”

“…The Plio-Pleistocene to present-day rock uplift (Serpelloni et al 2013) and exhumation (Fox et al 2015) documented in the European western and central Alps could be partly explained by an erosion-driven isostatic rebound (Schlunegger and Hinderer 2003;Cederbom et al 2004;Champagnac et al 2007Champagnac et al , 2009van der Beek and Bourbon 2008;Valla et al 2011) and/or by deep-seated processes such as slab breakoff (Sue et al 1999;Lippitsch et al 2003;Baran et al 2014;Fox et al 2015). In the Alpine realm, including the Jura arc, Serpelloni et al (2013) established a positive correlation between uplift rates and topography, with uplift rates ranging from 1 to 3 mm/year in the core of the Alps, and from 0.5 to 1.5 mm/year within the Jura Mountains.…”

Glacial buzzcutting limits the height of tropical mountains

“…Furthermore, most mountain ranges affected by Pleistocene glaciation have a hypsometric maximum between the upper and lower bounds of ELA fluctuation, much in the way that Brozović et al (1997) first described the glacial buzzsaw's signature in the Karakoram. It should also be noted that thermochronometric data support the 20 coincidence of a rapid shift in exhumation rate and the onset of Pleistocene glaciation in many places that bear the glacial buzzsaw signature (Thomson et al, 2010;Shuster, 2011;Herman et al, 2013;Fox et al, 2015), thus adding confidence that, at least in some places, the topographic signal of buzzcutting is matched by an expected increase in exhumation rate coincident with Pleistocene glaciation. In summary, the glacial buzzsaw hypothesis is presently supported by a topographic signature that can be found on a global scale, 25…”