Origin of desert loess from some experimental observations

Whalley, W. Brian; Marshall, John R.; Smith, Bernard

doi:10.1038/300433a0

Cited by 114 publications

(61 citation statements)

References 18 publications

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“…His experimental error was to use perfect quartz particles as his impactors; these tended to lack internal defects and be very resistant to breakage (see discussion [19]). When Whalley et al [4] repeated the experiments with more realistic material, i.e. quartz from granite containing internal stresses, silt sized quartz particles were produced.…”

Section: Abrasion Experimentsmentioning

confidence: 99%

“…There has been considerable discussion about the possibility of producing particles by aeolian impact [4,[15][16][17].…”

Section: Impact Mechanismsmentioning

confidence: 99%

“…Much of the discussion has concerned the production of loess sized particles (say around 30 μm) of quartz, from impactors which were sand sized quartz particles (say around 500 μm). Whalley et al [4] produced some elegant ideas which would allow the enormous loess deposits of North China to be produced by impact shattering of particles in the northern deserts. The result of a high energy impact may be a shattering of a particle into relatively large fragments, or the chipping off of a small fragment, the removal of a small projection, the formation of a small particle by stress combination, or there may be no product at all, simply a rebound.…”

Section: Impact Mechanismsmentioning

confidence: 99%

“…Loess emanating from glaciated areas, whether through latitude or altitude, has been widely seen as the product of glacial grinding, although this simple view is now being modified [1]; where the source is thought to be a hot desert opinions are still divided between those who favour weathering, especially by salt and frost, those who promote abrasion by running water or wind, and those who believe that the fine particles were brought into the desert regions from zones of particle formation [2]. The abrasion group includes proponents of fracture of suitable grains by interparticle impact; a mechanism proposed by Smalley & Vita-Finzi [3] but developed by Whalley et al [4].…”

Section: Introductionmentioning

confidence: 99%

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Loess and dust on Earth and Mars: particle generation by impact mechanisms

O’Hara-Dhand

Taylor²,

Smalley

et al. 2010

Open Geosciences

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Impact between windblown quartz grains as a source of desert dust is consistent with laboratory abrasion experiments and has received some field confirmation in the Negev. The suggestion is that an important process on Mars now gains support from laboratory studies; even though their geochemical interpretation is controversial, they show that dust generation by impact is tenable even for quartz. A simple mechanism for small dust production from sand seas is proposed; internal stresses can be mobilized by impact energy. A speculative mechanism (the andesite scenario) is proposed for fine particle production by particle impact on Mars. The internal stress range in terrestrial sand grains may vary, depending on the nature of the source rock, and this may influence particle production by impact processes.

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Section: Abrasion Experimentsmentioning

confidence: 99%

“…There has been considerable discussion about the possibility of producing particles by aeolian impact [4,[15][16][17].…”

Section: Impact Mechanismsmentioning

confidence: 99%

Section: Impact Mechanismsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Loess and dust on Earth and Mars: particle generation by impact mechanisms

O’Hara-Dhand

Taylor²,

Smalley

et al. 2010

Open Geosciences

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“…Mechanisms are still being suggested (e.g. Nahon andTrompette, 1982, Whalley andothers, 1982) but Hardcastle not only detected the problem, he provided an elegantly worked-out solution: "Having found the loess to be a dry-land deposit, we must find the still-missing factor in the dust-heap theory.…”

Section: In the Years 1890-91 John Hardcastle Published Four Papers Imentioning

confidence: 99%

Early Discoverers XXXIII: John Hardcastle on Glacier Motion and glacial Loess

Smalley

1983

J. Glaciol.

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Interglacial dust, ocean fertilisation and Neoproterozoic earth oxygenation

DaSilva,

Pufahl,

James

2024

The Depositional Record

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Feedback processes that drove Earth's second major increase in ocean–atmosphere oxygen levels during the Neoproterozoic are poorly constrained. Variability in seawater redox over geological timescales is commonly linked to changes in the biogeochemical cycling of P and thus the rate of primary production and generation of photosynthetic oxygen. In the modern surface ocean, an important source of bioessential P and micronutrients (Fe, Cu, Co, Zn, Mo, Cr and Ni) is aeolian dust derived from deserts and arid, post‐glacial landscapes. It is interpreted herein that glacial retreat following the Sturtian (ca 717 to 660 Ma) and Marinoan (ca 650 to 635 Ma) snowball glaciations provided copious dust to the global ocean. Correlation of interglacial siltstone successions in palaeogeographical context suggests that such dust accumulation was diachronous and concentrated in the palaeo‐horse latitudes (30° N and 30° S). Delivery of this dust from continents is likely reflected in the steep increase in global radiogenic Sr isotope values (87Sr/86Sr) in post‐Sturtian carbonates, and changes in the δ18O signatures of Cryogenian zircons derived from subducted marine sediments. Accumulation of sedimentary organic matter also peaked during interglacial periods, suggesting a causal link between glaciation, aeolian dust and primary production. This relationship implies windblown dust was an important source of P and micronutrients for an evolving biological pump that stimulated primary production, enhanced burial of organic carbon and increased ocean–atmosphere oxygen concentrations. Thus, delivery of aeolian dust to the global ocean was likely critical for sustaining Earth's second major increase in oxygen. Sequestration of atmospheric CO2 in organic‐rich siltstones and shales is also interpreted to have been an important negative feedback process, which together with silicate weathering, prevented runaway greenhouse conditions during interglacial periods. The oxygen produced by this aeolian marine biological pump may have helped pave the way for the evolution of multicellular animals in the Ediacaran.

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Origin of desert loess from some experimental observations

Cited by 114 publications

References 18 publications

Loess and dust on Earth and Mars: particle generation by impact mechanisms

Loess and dust on Earth and Mars: particle generation by impact mechanisms

Early Discoverers XXXIII: John Hardcastle on Glacier Motion and glacial Loess

Interglacial dust, ocean fertilisation and Neoproterozoic earth oxygenation

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