4.12 Weathering in Arid Regions

Warke, Patricia

doi:10.1016/b978-0-12-374739-6.00060-9

Cited by 13 publications

(4 citation statements)

References 111 publications

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“…The relatively young age of 35 ky (Cortés et al, 2012) for smooth fan surfaces along the Mejillones fault (90 km south of the fan studied here) implies that modification rates along the Ata-cama coast are signicantly higher than in most other arid environments. As moisture availability is generally the limiting factor for weathering in arid climates (e.g., Warke, 2013), the cause of rapid fan-surface modification along the Atacama coast is the camanchaca, which provides considerable amounts of moisture and dissolved salts leading to extremely high weathering rates (Eriksen, 1981;Schemenauer and Cereceda, 1992;Berger, 1993;Goudie et al, 2002). This effectively decreases the morphological factor (Eq.…”

Section: Discussionmentioning

confidence: 99%

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

et al. 2014

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. (2014) 'Debris-ow dominance of alluvial fans masked by runo reworking and weathering. ', Geomorphology., Further information on publisher's website:http://dx.doi.org/10.1016/j.geomorph.2014.04.028Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Geomorphology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in Geomorphology, 217, 2014Geomorphology, 217, , 10.1016Geomorphology, 217, /j.geomorph.2014 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractArid alluvial fan aggradation is highly episodic and fans often comprise active and inactive sectors. Hence morphology and texture of fan surfaces are partly determined by secondary processes of weathering and erosion in addition to primary processes of aggradation. This introduces considerable uncertainty in the identification of formative processes of terrestrial and Martian fans from aerial and satellite imagery. The objectives of this study are (i) to develop a model to describe the sedimentological and morphological evolution of inactive fan surfaces in arid settings, and (ii) to assess the relative importance of primary processes of aggradation and secondary processes of weathering and reworking for surface morphology and sedimentology and for the stratigraphic record. We studied an alluvial fan characterized by a recently active sector and a long-abandoned, inactive sector along the coast of the hyperarid Atacama Desert. Here, rates of primary geomorphic activity are exceptionally low because of extreme aridity, whilst weathering * Corresponding author. Tel.: +3130 2532778, E-mail: t.dehaas@uu.nl Preprint submitted to GeomorphologyJune 2, 2014rates are relatively high because of the effects of coastal fogs. Long-term processes of fan aggradation and reworking were determined through sedimentological facies analysis of stratigraphic sections. Ground surveys for textural and morphological patterns at the fan surface were integrated with remote-sensing by an Unmanned Airborne Vehicle (UAV). Discharges and sediment-transport capacities were calculated to estimate the efficiency of secondary runoff in reshaping the inactive fan sector. Stratigraphic sections reveal that the fan was dominantly aggraded by debris flo...

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Section: Discussionmentioning

confidence: 99%

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

et al. 2014

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“…In arid environments, frost, salt, and chemical weathering rates are all limited by moisture availability. Given adequate moisture, these weathering mechanisms substantially exceed insolation weathering rates [ Warke , ]. Gully activity and fan formation, during periods of high obliquity [e.g., Dickson and Head , ], imply the presence of sufficient liquid water for enhanced salt and chemical weathering and possibly frost weathering during certain periods and at certain locations in the late Amazonian.…”

Section: Discussionmentioning

confidence: 99%

Local late Amazonian boulder breakdown and denudation rate on Mars

Haas

Hauber

Kleinhans

2013

Geophysical Research Letters

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[1] Inactive fan surfaces become smoother and develop desert pavement over time by weathering and erosion. We use this mechanism to estimate late Amazonian boulder breakdown and surface denudation rates on a young ( 1.25 Ma) (Schon et al., 2009) fan on Mars. This is done by comparing boulder size and surface relief between lobes of different ages. The boulder breakdown rate is 3.5 m/Myr, surface smoothing (denudation) rate is approximated as 0.89 m/Myr. These rates exceed previous estimates for the Amazonian by orders of magnitude. We attribute this to locality, high initial smoothing rates after morphological activity and obliquity and eccentricity-driven variation in the availability of (metastable) liquid water, which acts as a catalyst for weathering during these periods. The results have major implications for process interpretation of Martian landforms, as they imply that typical small-scale morphology may be subdued within <1 Myr. Citation:de Haas, T., E. Hauber, and M. G. Kleinhans (2013), Local late Amazonian boulder breakdown and denudation rate on Mars,

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“…In contrast, the greatly enhanced backweathering rates in gully alcoves may result from the presence of liquid water, CO 2 ice, or both. The presence of liquid water generally results in enhanced weathering rates as shown on Earth [e.g., Selby, 1980;Sass, 2005;Krautblatter and Moser, 2009;Warke, 2013], by enhancing chemical modification rates, freeze-thaw cycles, and hydration-dehydration and crystallization cycles in the presence of salts, which are abundant on Mars [e.g., Clark and Hart, 1981;Rodriquez-Navarro, 1998;Jagoutz, 2006;Head et al, 2011].…”

Section: The Potential Role Of Liquid Water In Backweathering and Impmentioning

confidence: 99%

“…Many of these factors are interconnected, and weathering is indirectly included in many of these parameters, e.g., the loss of rock strength and opening of joints are largely weathering phenomena. Lastly, the presence of liquid water greatly enhances weathering and thereby backweathering rates [e.g., Selby , ; Sass , ; Viles , ; Warke , ].…”

Section: Introductionmentioning

confidence: 99%

Recent (Late Amazonian) enhanced backweathering rates on Mars: Paracratering evidence from gully alcoves

2015

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract Mars is believed to have been exposed to low planet-wide weathering and denudation since the Noachian. However, the widespread occurrence of alcoves at the rim of pristine impact craters suggests locally enhanced recent backweathering rates. Here we derive Late Amazonian backweathering rates from the alcoves of 10 young equatorial and midlatitude craters. The enhanced Late Amazonian Martian backweathering rates (10 −4 -10 −1 mm yr −1 ) are approximately 1 order of magnitude higher than previously reported erosion rates and are similar to terrestrial rates inferred from Meteor crater and various Arctic and Alpine rock faces. Alcoves on initially highly fractured and oversteepened crater rims following impact show enhanced backweathering rates that decline over at least 10 1 -10 2 Myr as the crater wall stabilizes. This "paracratering" backweathering decline with time is analogous to the paraglacial effect observed in rock slopes after deglaciation, but the relaxation timescale of 10 1 -10 2 Myr compared to 10 kyr of the Milankovitch-controlled interglacial duration questions whether a paraglacial steady state is reached on Earth. The backweathering rates on the gullied pole-facing alcoves of the studied midlatitude craters are much higher (∼2-60 times) than those on slopes with other azimuths and those in equatorial craters. The enhanced backweathering rates on gullied crater slopes may result from liquid water acting as a catalyst for backweathering. The decrease in backweathering rates over time might explain the similar size of gullies in young (<1 Ma) and much older craters, as alcove growth and sediment supply decrease to low-background rates over time.

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4.12 Weathering in Arid Regions

Cited by 13 publications

References 111 publications

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering

Local late Amazonian boulder breakdown and denudation rate on Mars

Recent (Late Amazonian) enhanced backweathering rates on Mars: Paracratering evidence from gully alcoves

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