Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades

Abstract

Past studies of tectonically active mountain ranges have suggested strong coupling and feedbacks between climate, tectonics and topography. For example, rock uplift generates topographic relief, thereby enhancing precipitation, which focuses erosion and in turn influences rates and spatial patterns of further rock uplift. Although theoretical links between climate, erosion and uplift have received much attention, few studies have shown convincing correlations between observable indices of these processes on mountain-range scales. Here we show that strongly varying long-term (>10(6)-10(7) yr) erosion rates inferred from apatite (U-Th)/He cooling ages across the Cascades mountains of Washington state closely track modern mean annual precipitation rates. Erosion and precipitation rates vary over an order of magnitude across the range with maxima of 0.33 mm yr(-1) and 3.5 m yr(-1), respectively, with both maxima located 50 km west (windward) of the topographic crest of the range. These data demonstrate a strong coupling between precipitation and long-term erosion rates on the mountain-range scale. If the range is currently in topographic steady state, rock uplift on the west flank is three to ten times faster than elsewhere in the range, possibly in response to climatically focused erosion.

Tectonic controls of Holocene erosion in a glaciated orogen

“…6d). Even in the neighboring glaciated Cascade Range, ∼ 70 km to the east of the Olympic Mountains, where the modern precipitation gradient is not as large, there is a strong linear relationship indicating erosion scales with precipitation over diverse timescales, thus making it an important condition for setting Holocene and older erosion rates (Reiners et al, 2003;Moon et al, 2011).…”

Geochronology of the Baye Mn oxide deposit, southern Yunnan Plateau: Implications for the late Miocene to Pleistocene paleoclimatic conditions and topographic evolution

“…The formation and preservation of weathering profiles, and their depth and stratigraphic complexity, reflect the balance between weathering and erosion (Tardy and Roquin, 1992;Thomas, 1994). Previous studies have shown that erosional processes are jointly related to climatic changes, tectonic uplift, and topographic evolution (Molnar and England, 1990;Montgomery and Brandon, 2002;Reiners et al, 2003;Burbank et al, 2003). Thus, investigating the mineralogy, geochemistry, stratigraphy, and geochronology of weathering profiles may provide valuable information on climatic, landscape, and tectonic evolution in the geological past (Tardy, 1993;Vasconcelos, 4 1999a; Girard et al, 2002).…”

Tectonic controls of Holocene erosion in a glaciated orogen

“…6D). Even in the neighboring, 370 glaciated Cascade Range (~70 km to the east of the Olympic Mountains) where the modern precipitation gradient is not as large, there is a strong linear relationship suggesting erosion scales with precipitation over diverse timescales, thus making it an important condition for setting Holocene and older erosion rates (Moon et al, 2011;Reiners et al, 2003). Second, our data do not suggest that destabilization of the landscape via glacial incision has played a primary role in setting the Holocene erosion pattern.…”

“…There are many examples of ranges where there have been significant changes to topography [Adams and Ehlers, 2017;Brardinoni and Hassan, 2006;Simon H Brocklehurst and Whipple, 2007;Glotzbach et al, 2013;Hobley et al, 2010;D. R. 410 Montgomery, 2001;Robl et al, 2008] and erosion during and after glaciation (Moon et al, 2011;Reiners et al, 2003;Christeleit et al, 2017), and others where such changes are not clearly observed (Thomson et al, 2010). More generally, these changes were explored in a coupled ice dynamic/landscape evolution model testing the modification of topography and erosion rates due to alpine glaciation (Yanites and Ehlers, 2012).…”