Continental erosion and large‐scale relief

Abstract

A worldwide investigation of continental erosion is carried out by the study of large drainage basins, on the basis of hydrological data, environmental factors, and basin relief distribution. Inside each basin, mean geochemical and mechanical denudation rates are defined. A multicorrelation analysis shows that the mechanical denudation rates Ds are uncorrelated with environmental factors and correlated with mean basin elevation H, while chemical denudation rates Dd are insensitive to relief but correlated with mean annual precipitation. Furthermore, two linear relationships between H and •6Hare detected: (1) Ds (m/10 •yr) = 419 x 1 (m) -0.245, with V (explained variance) = 95.1%; this law concerns basins related to orogenies younger than 250 Ma. The negative intercept is interpreted as a continental sedimentation rate of 245 m/m.y. An alternative model in which one invokes a critical elevation, separating erosion from sedimentation, is equally successful and leads to lower sedimentation rates (60-110 m/m.y.). For both models, one derives from the slope of the adjustments, erosion time constants Copyright 1988 by the American Geophysical Union Paper number 7T0908. 0278-7407/88/007T-0908510. O0 on the •der of 2.5 m.• (2) Ds (m/103 yr) = 61 x 10 VH (m), with = 86.5%

Crustal redistribution, crust–mantle recycling and Phanerozoic evolution of the continental crust

“…Tectonic forces are only capable of sustaining high orogenic elevations while they are still active because erosion will tend to remove "excess" crust (Ahnert, 1970;Pinet and Souriau, 1988) and thin the crust back to the equilibrium values of ca. 38 km, close to sealevel (Christensen and Mooney, 1995).…”

Tectonics, climate, and mountain topography

“…Based on Late Pleistocene erosion rates calculated from riverborne cosmogenic 10 Be in SE Tibet, Henck et al [2011] recently postulated that the tectonic setting is more prominent than rainfall or relief to explain erosion rates, but the same method led Moon et al [2011] to the opposite conclusion for the Washington Cascades, where denudation scales with precipitation rate. Several studies have attempted to provide a global (i.e., worldwide) view of the relationship of Earth's topography to snow lines and glaciations [Broecker and Denton, 1989;Egholm et al, 2009;Pedersen et al, 2010;Porter, 1977], to links between climate and erosion [Molnar, 2004;Willenbring and von Blanckenburg, 2010;Zhang et al, 2001], to relationships between relief and erosion [Ahnert, 1970;Dietrich et al, 2003;Montgomery and Brandon, 2002;Portenga and Bierman, 2011;Simoes et al, 2010;von Blanckenburg, 2005], and to relationships linking all of climate, topography, and erosion [Pinet and Souriau, 1988], but to the best of our knowledge, none has tried to relate topography to quantitative measures of both climate and tectonics.…”

Sediment budget in the Ucayali River basin, an Andean tributary of the Amazon River

“…However, SSY spatial distribution is heterogeneous along the Andes, because of the different environmental conditions including climate, soil and topography. Since the early work of Ahnert (1970) associating the age of a mountain range and its denudation rates, numerous studies have contributed to the knowledge of the relation between tectonic, topography, lithology, climate, vegetation and erosion (Milliman & Meade, 1983;Pinet & Souriau, 1988;Milliman & Syvitski, 1992;Summerfield & Hulton, 1994;Dadson et al, 2003Dadson et al, , 2004Aalto et al, 2006;Syvitski & Milliman, 2007;Pepin et al, 2013). All those works suggest a heterogeneous spatial distribution of the denudation rates in the Andean range due to the interaction between climate and orography, from north to south and from east to west.…”