The interplay between physical and chemical erosion over glacial-interglacial cycles

Schachtman, N. S.; Roering, Joshua J.; Marshall, Jill; Gavin, Daniel G.; Granger, Darryl E.

doi:10.1130/g45940.1

Cited by 17 publications

(7 citation statements)

References 32 publications

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“…The variations in chemical erosion rate within basins in these simulations have implications for interpretations of the sedimentary record, such as measurements of sediment flux and composition in montane lakes (e.g., Schachtman et al, 2019) and marine sediments (e.g., Zachos et al, 2001, 2008). It is well known that changes in sedimentary signatures are not synchronous with the drivers of change due to time lags in the propagation of signals through the channel networks (e.g., Braun et al, 2015).…”

Section: Discussionmentioning

confidence: 98%

The Importance of Hillslope Scale in Responses of Chemical Erosion Rate to Changes in Tectonics and Climate

Ferrier

Perron

2020

JGR Earth Surface

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Chemical erosion is of wide interest due to its influence on topography, nutrient supply to streams and soils, sediment composition, and Earth's climate. While controls on chemical erosion rate have been studied extensively in steady-state models, few studies have explored the controls on chemical erosion rate during transient responses to external perturbations. Here we develop a numerical model for the coevolution of soil-mantled topography, soil thickness, and soil mineralogy, and we use it to simulate responses to step changes in rates of rock uplift, soil production, soil transport, and mineral dissolution. These simulations suggest that tectonic and climatic perturbations can generate responses in soil chemical erosion rate that differ in speed, magnitude, and spatial pattern and that climatic and tectonic perturbations may impart distinct signatures on hillslope mass fluxes, soil chemistry, and sediment composition. The response time of chemical erosion rate is dominantly controlled by hillslope length and is secondarily modulated by rates of rock uplift, soil production, transport, and mineral dissolution. This strong dependence on drainage density implies that a landscape's chemical erosion response should depend on the relative efficiencies of river incision and soil transport and thus may be mediated by climatic and biological factors. The simulations further suggest that the timescale of the hillslope response may be long relative to that of river channel profiles, implying that chemical erosion response times may be limited more by the sluggishness of the hillslopes than by the rate of signal propagation through river channel profiles. Plain Language Summary The flux of dissolved solutes out of mountainous regions is of wide interest due to its influence on topography, ecosystems, sediment, and climate. Here we develop a new model to calculate the responses of chemical erosion rate to changes in rates of rock uplift, soil production, soil transport, and mineral dissolution. These simulations suggest that tectonic and climatic perturbations can generate distinct responses in soil chemical erosion rate. They also show that the time it takes chemical erosion rates to respond to changes in climate or tectonics is primarily controlled by the length of the hillslope and secondarily by rates of rock uplift, soil production, soil transport, and mineral dissolution. This strong dependence on hillslope length implies that chemical erosion responses may be affected by climate and life to the extent that these factors affect how easily rivers cut through rock and how easily soil moves downhill. This further implies that chemical erosion response times may be limited mainly by how slowly hillslopes respond to changes in climate and tectonics, rather than by how slowly river networks do.

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Section: Discussionmentioning

confidence: 98%

The Importance of Hillslope Scale in Responses of Chemical Erosion Rate to Changes in Tectonics and Climate

Ferrier

Perron

2020

JGR Earth Surface

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“…189,190 . Elsewhere, detrital records 191 have also been used to reconstruct changes in weathering intensity and, when paired with data on paleo-denudation rates, to infer the coupling between erosion and weathering over glacial-interglacial timescales 192 .…”

Section: Records From Geological Archivesmentioning

confidence: 99%

Mountains, erosion and the carbon cycle

Hilton

West

2020

Nat Rev Earth Environ

262

209

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Mountain building results in high erosion rates and the interaction of rocks with the atmosphere, water and life. Carbon transfers that result from increased erosion could control the evolution of Earth's long-term climate. For decades, attention has focused on the hypothesised role of mountain building in drawing down atmospheric carbon dioxide (CO2) via silicate weathering. However, it is now recognized that mountain building and erosion affect the carbon cycle in other important ways. For example, erosion mobilises organic carbon (OC) from terrestrial vegetation, transferring it to rivers and sediments and thereby acting to draw down atmospheric CO2 in tandem with silicate weathering. Meanwhile, exhumation of sedimentary rocks can release CO2 through the oxidation of rock OC and sulfide minerals. In this Review we examine the mechanisms of carbon exchange between rocks and the atmosphere and discuss the balance of CO2 sources and sinks. Our Review demonstrates that OC burial and oxidative weathering, not widely considered in most models, control the net CO2 budget associated with erosion. Therefore, lithology strongly influences the impact of mountain building on the global carbon cycle, with an orogeny dominated by sedimentary rocks, and thus abundant rock OC and sulfides, tending towards being a CO2 source.

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“…dry periods (Berner et al, 1983;Dixon et al, 2016;Jenny, 1941;Schachtman et al, 2019), potentially increasing the ratio of pristine source rock to weathered soil in suspended sediments and thus the riverine PIC flux. Moreover, glacial activity during cooler periods may accelerate erosion and thus PIC production and potentially preservation (because of decreased residence times).…”

Section: Natural Controls Of Pic and Their Variation Through Timementioning

confidence: 99%