A laboratory model of splash‐form tektites

Elkins-Tanton, Linda T.; Aussillous, Pascale; Bico, José; Quéré, David; Bush, John W. M.

doi:10.1111/j.1945-5100.2003.tb00317.x

Cited by 43 publications

(42 citation statements)

References 30 publications

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“…Splashform tektites are acknowledged by most workers to have formed from the rotation of ejected melt under the influence of surface tensions (Baker 1958;Ford 1988;Elkins-Tanton et al 2003). Droplets are the most common splashform Darwin glass.…”

Section: Discussionmentioning

confidence: 99%

Physical distribution trends in Darwin glass

Howard

2009

Meteorit & Planetary Scien

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Abstract— Darwin glass formed by impact melting, probably during excavation of the 1.2 km diameter Darwin crater, Tasmania, Australia. The glass was ejected up to 20 km from the source crater and forms a strewn field of >400 km2. There is at least 11,250 m3of glass in the strewn field and relative to the size of the crater this is the most abundant ejected impact glass on Earth. The glass population can be subdivided on the basis of shape (74% irregular, 20% ropy, 0.5% spheroid, 6% droplet, and 0.7% elongate) and color (53% dark green, 31% light green, 11% black, and 5% white). The white glasses contain up to 92 wt% SiO2 and are formed from melting of quartzite. Black glasses contain a minimum of 76 wt% SiO2 and formed from melting of shale. Systematic variations in the proportion of glasses falling into each of the color and shape classes relative to distance from the crater show: 1) a decrease in glass abundance away from the crater; 2) the largest fragments of glass are found closest to the crater; 3) small fragments (<2 g) dominate finds close to the crater; 4) the proportion of white glass is greatest closest to the crater; 5) the proportion of black glass increases with distance from the crater and 6) the proportion of splashform glasses increases with distance from the crater. These distribution trends can only be explained by the molten glass having been ballistically ejected from Darwin crater during impact and are related to 1) the depth of excavation from the target rock stratigraphy and/or 2) viscosity contrasts between the high and low SiO2 melt. The high abundance and wide distribution of ejected melt is attributed to a volatile charged target stratigraphy produced by surface swamps that are indicated by the paleoclimate record.

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Section: Discussionmentioning

confidence: 99%

Physical distribution trends in Darwin glass

Howard

2009

Meteorit & Planetary Scien

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“…The net effect of the viscosity is to increase the critical Weber number needed before disruption of the liquid sphere occurs. In looking at the movement of liquid spheres through a fluid, the critical value of the Weber number that determines when the ram pressure of the fluid exceeds the surface tension of the liquid has the form (Elkins-Tanton et al 2003):…”

Section: Chondrule Collisionsmentioning

confidence: 99%

Chondrule collisions in shock waves

Ciesla

2006

Meteoritics &Amp; Planetary Science

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Chondrule collisions in shock wavesAbstract-Detailed numerical models have shown that solar nebula shock waves would be able to thermally process chondrules in a way that is consistent with experimental constraints. However, it has recently been argued that the high relative velocities that would be generated between chondrules of different sizes immediately behind the shock front would lead to energetic collisions that would destroy the chondrules as they were processed rather than preserving them for incorporation into meteorite parent bodies. Here the outcome of these collisions is quantitatively explored using a simple analytic expression for the viscous dissipation of collisional energy in a liquid layer. It is shown that molten chondrules can survive collisions at velocities as high as a few hundred meters per second. It is also shown that the thermal evolution of chondrules in a given shock wave varies with chondrule size, which may allow chondrules of different textures to form in a given shock wave. While experiments are needed to further constrain the parameters used in this work, these calculations show that the expected outcomes from collisions behind shock waves are consistent with what is observed in meteorites.

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“…The liquefied rock was then ejected and aerodynamically shaped into spherules, teardrops, ovoids, and dumbbells that are often vesicular and often contain lechatelierite. Collectively, these are called splash-form tektites or microtektites (8,27,41). Most YDB spherules are highly reflective spheroids similar to those in each group, but ∼10-20% of them exhibit complex aerodynamic shapes, consistent only with splash-formed microtektites.…”

Section: Melrose Blackwatermentioning

confidence: 99%

“…Such spherules can appear as multiples (i.e., are accretionary), are typically nonvesicular, and do not contain lechatelierite (27,41). The second is a melt-and-quench group, in which compressive and frictional heating by the impactor subjected the target rocks and impactor to high temperatures that boiled both of them (41).…”

Section: Melrose Blackwatermentioning

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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A laboratory model of splash‐form tektites

Cited by 43 publications

References 30 publications

Physical distribution trends in Darwin glass

Physical distribution trends in Darwin glass

Chondrule collisions in shock waves

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

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