A frost “buzzsaw” mechanism for erosion of the eastern Southern Alps, New Zealand

Hales, Tristram C.; Roering, J. J.

doi:10.1016/j.geomorph.2008.12.012

Cited by 116 publications

(104 citation statements)

References 102 publications

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“…In northern Bhutan, these features have the potential to supply streams with sediment eroded from below the depth of significant cosmic-ray penetration (attenuation depths of 160 g cm −2 , or about 60 cm; Gosse and Phillips, 2001;Balco et al, 2008). The breakdown of colluvium and hillslope material in these cold and high-elevation catchments is likely facilitated by effective freeze-thaw cycles (Matsuoka, 1990a) and frost-cracking (Coutard and Francou, 1989;Matsuoka, 1990bMatsuoka, , 1994Hales and Roering, 2009;Delunel et al, 2010). The widespread presence of debris-covered glaciers in northern Bhutan (Nagai et al, 2013) attests to the frequent occurrence of these cold-climate processes.…”

Section: Discussionmentioning

confidence: 99%

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

et al. 2015

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Section: Discussionmentioning

confidence: 99%

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

et al. 2015

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“…Most glacial erosion models assume erosion rate to be proportional to ice sliding velocity raised to some power (Harbor and others, 1988) and periglacial processes such as frost cracking can reduce high peaks to rock debris easily transported away by glaciers (Hales and Roering, 2009;Delunel and others, 2010). These two processes imply that glacial erosion is most efficient at and above the Equilibrium Line Altitude (ELA), that separates the ice accumulation and ablation regions of a glacier (Anderson and others, 2006;Egholm and others, 2009;Sternai and others, 2013), at least outside of the high latitudes (Thomson and others, 2010).…”

Section: Plio-pleistocenementioning

confidence: 99%

The Exhumation history of the European Alps inferred from linear inversion of thermochronometric data

Fox

Herman

Willett

et al. 2016

American Journal of Science

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ABSTRACT. Thermochronometric data collected across the Alps over the last three decades allows for investigation of the evolution of this orogen, which is subject to changes in climate and geodynamics. Exhumation rates are inferred from the thermochronometric ages using a statistical inversion method based on the fact that the distance a sample traveled since closure is equal to the integral of the exhumation rate from the present day to the age of the sample. Exhumation rates are assumed to be spatially correlated but are free to vary through time. This results in the quantification of exhumation rates across the Alps, since 32 Ma, along with assessments of the quality of these inferences. We find that exhumation rates are initially fast in the internal arc of the Western Alps at rates up to 0.8 km/Myr at 30 Ma, decreasing at 20 Ma to 0.3 km/Myr to remain slow to the present. At the same time, around 20 Ma, rates across the External Crystalline Massifs of Western Alps increase to 0.6 km/Myr. We also find that the onset of high exhumation rates in the Tauern Window and the Lepontine Dome occurs at around 20 Ma, a time characterized by major reorganizations in the Alpine chain. A general increase in exhumation rates at around 5 Ma over the entire Alps is not confirmed. Instead we find that the Western Alps exhibit a 2 to 3 fold increase in exhumation rate over the last 2 Ma, during a recent event not seen further east, in spite of very similar topographic characteristics. We attribute this strong signal to detachment of the European slab in the Western Alps, combined with efficient glacial erosion.

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“…In fact, we found that published values of ELAs from the same ranges can differ by as much as 1000 m, mostly because of the climate characteristics, the hypsometry, and the orientation of the glaciated basins [Allen, 1998;Flint, 1971;Gilbert, 1904;Huybers and Roe, 2009]. Hence we are forced to use a less direct measure of glaciation, but one that takes into account other periglacial processes, such as frost shattering [Delunel et al, 2010;Hales and Roering, 2009], which may affect topography at high latitude/high elevation. Note that when coslat increases, the latitude decreases.…”

Section: Climate Variablesmentioning

confidence: 99%

Tectonics, climate, and mountain topography

et al. 2012

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[1] By regressing simple, independent variables that describe climate and tectonic processes against measures of topography and relief of 69 mountain ranges worldwide, we quantify the relative importance of these processes in shaping observed landscapes. Climate variables include latitude (as a surrogate for mean annual temperature and insolation, but most importantly for the likelihood of glaciation) and mean annual precipitation. To quantify tectonics we use shortening rates across each range. As a measure of topography, we use mean and maximum elevations and relief calculated over different length scales. We show that the combination of climate (negative correlation) and tectonics (positive correlation) explain substantial fractions (>25%, but <50%) of mean and maximum elevations of mountain ranges, but that shortening rates account for smaller portions, <25%, of the variance in most measures of topography and relief (i.e., with low correlations and large scatter). Relief is insensitive to mean annual precipitation, but does depend on latitude, especially for relief calculated over small ($1 km) length scales, which we infer to reflect the importance of glacial erosion. Larger-scale (averaged over length scales of $10 km) relief, however, correlates positively with tectonic shortening rate. Moreover, the ratio between small-scale and large-scale relief, as well as the relative relief (the relief normalized by the mean elevation of the region) varies most strongly with latitude (strong positive correlation). Therefore, the location of a mountain range on Earth with its corresponding climatic conditions, not just tectonic forcing, appears to be a key factor in determining its shape and size. In any case, the combination of tectonics and climate, as quantified here, can account for approximately half of the variance in these measures of topography. The failure of present-day shortening rates to account for more than 25% of most measures of relief raises the question: Is active tectonics overrated in attempts to account for present-day relief and exhumation rates of high terrain?

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A frost “buzzsaw” mechanism for erosion of the eastern Southern Alps, New Zealand

Cited by 116 publications

References 102 publications

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be

The Exhumation history of the European Alps inferred from linear inversion of thermochronometric data

Tectonics, climate, and mountain topography

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