Studies of particles for extraterrestrial origin: 4. Microscopic spherules from recent volcanic eruptions

Wright, Frances W.; Hodge, P. W.

doi:10.1029/jz070i016p03889

Cited by 30 publications

(21 citation statements)

References 6 publications

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“…The ellipsoidal shape of these particles indicates that they were once molten droplets. The similarity of the chemical analysis to the analysis of magnetic spheroids derived from recent volcanic eruptions (12) and the proximity of these samples to the Hawaiian Islands suggests a volcanic origin. Two particles have characteristics common to more than one category; they have internal structures similar to those of Groups I and II but chemical compositions similar to Group III particles.…”

mentioning

confidence: 75%

The Ocean: A Natural Source of Carbon Monoxide

Swinnerton

Linnenbom

Lamontagne

1970

Science

128

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The surface waters of the western Atlantic are supersaturated with respect to the partial pressure of carbon monoxide in the atmosphere. Under these conditions, the net transport of carbon monoxide across the air-sea interface must be from the sea into the atmosphere. Thus, the ocean appears to act as a source of carbon monoxide. The ocean may be the largest known natural source of this gas, contributing possibly as much as 5 percent of the amount generated by burning of fuels by man.

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confidence: 75%

The Ocean: A Natural Source of Carbon Monoxide

Swinnerton

Linnenbom

Lamontagne

1970

Science

128

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“…The origin of the DSDP spherules is ascribed to submarine volcanism, but their SiC>2 content is ~50 percent (Von der Borch, 1971). The Fe contents of volcanic microspherules from a variety of locales is generally less than 30 percent (Wright and Hodge, 1965), which further distinguishes them from the Fe-rich spheroids. Spheres containing skeletal and dendritic magnetite have been found in association with kimberlite pipes and other explosive endogenous structures.…”

Section: Volcanicmentioning

confidence: 99%

The significance of magnetic spheroids and magnesioferrite occurring in K/T boundary sediments

Cisowski¹

1990

Geological Society of America Special Papers

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A comparison of the high field magnetic properties of small magnetic spheroids associated with some marine Cretaceous/Tertiary (K/T) boundary clays and of spheroidal or glassy byproducts of impact indicates significant differences. Tektite glass may have a similar room-temperature coercivity spectrum, but low-temperature measurements reveal the presence of abundant very fine superparamagnetic grains. Ablation spherules are significantly more magnetic than K/T spherules, and their isothermal remanence acquisition and demagnetization behaviors also differ from the "single domain" character of the boundary spherules. Impact glass from terrestrial craters and upper Eocene clinopyroxene spherules exhibit significantly higher remanent coercive force values, probably reflecting compositional differences.Among nonimpact materials, industrial fly ash represents a close magnetic analogue to the K/T boundary magnetic forms. The K/T spherules also share some morphological and chemical features with magnetic spherules present in fly ash. Magnesioferrite and Fe-spinel, two rare natural minerals present in the K/T spheroids, have been associated with naturally combusted bituminous shales. This suggests that a hypothesized global combustion event synchronous with the termination of the Cretaceous may have also, in part, involved the combustion of fossil fuel. Cisowski, S. M., 1990, The significance of magnetic spheroids and magnesioferrite occurring in K/T boundary sediments, in Sharpton

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“…In another study, Pigati et al (14) confirmed the previously reported YDB peak in spherules at Murray Springs, Arizona, and also claimed to find several non-YDB spherule peaks in Chile. However, the Chilean sites are known to contain abundant volcanic spherules (22), and yet Pigati et al (14) did not perform any analyses of candidate spherules with SEM and EDS, which are crucial for differentiating impact-related YDB spherules from volcanic spherules, detrital magnetic grains, framboids, and other spherule-like particles.…”

Section: Significancementioning

confidence: 99%

Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago

Wittke

Weaver

Bunch

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

124

187

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Airbursts/impacts by a fragmented comet or asteroid have been proposed at the Younger Dryas onset (12.80 ± 0.15 ka) based on identification of an assemblage of impact-related proxies, including microspherules, nanodiamonds, and iridium. Distributed across four continents at the Younger Dryas boundary (YDB), spherule peaks have been independently confirmed in eight studies, but unconfirmed in two others, resulting in continued dispute about their occurrence, distribution, and origin. To further address this dispute and better identify YDB spherules, we present results from one of the largest spherule investigations ever undertaken regarding spherule geochemistry, morphologies, origins, and processes of formation. We investigated 18 sites across North America, Europe, and the Middle East, performing nearly 700 analyses on spherules using energy dispersive X-ray spectroscopy for geochemical analyses and scanning electron microscopy for surface microstructural characterization. Twelve locations rank among the world's premier end-Pleistocene archaeological sites, where the YDB marks a hiatus in human occupation or major changes in site use. Our results are consistent with melting of sediments to temperatures >2,200°C by the thermal radiation and air shocks produced by passage of an extraterrestrial object through the atmosphere; they are inconsistent with volcanic, cosmic, anthropogenic, lightning, or authigenic sources. We also produced spherules from wood in the laboratory at >1,730°C, indicating that impactrelated incineration of biomass may have contributed to spherule production. At 12.8 ka, an estimated 10 million tonnes of spherules were distributed across ∼50 million square kilometers, similar to well-known impact strewnfields and consistent with a major cosmic impact event.Clovis-Folsom | lechatelierite | tektite | wildfires

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Studies of particles for extraterrestrial origin: 4. Microscopic spherules from recent volcanic eruptions

Cited by 30 publications

References 6 publications

The Ocean: A Natural Source of Carbon Monoxide

The Ocean: A Natural Source of Carbon Monoxide

The significance of magnetic spheroids and magnesioferrite occurring in K/T boundary sediments

Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago

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