2016
DOI: 10.1002/2016gl070874
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Olivine settling in cosmic spherules during atmospheric deceleration: An indicator of the orbital eccentricity of interplanetary dust

Abstract: A new type of cosmic spherule is reported with textures suggesting settling of olivine during atmospheric deceleration. Numerical simulations of entry heating reveal that relict forsterite, which survives melting, can settle over the 1–2 s of flight at high entry angles and entry velocities up to 16 km s−1. Enhanced crystallization of phenocrysts by heterogeneous nucleation on accumulated relict forsterites is the most likely origin of the observed cumulate textures in cosmic spherules. Such textures in cosmic… Show more

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Cited by 17 publications
(20 citation statements)
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“…Typically, coarse‐PO spherules contain significant interstitial glass (>10 vol%) and low vesicle abundances (<10 vol%) and include particles with cumulate textures described by Genge et al. (). Coarse‐skeletal PO spherules are the most abundant group in the Larkman Nunatak collection comprising 43.9% of PO spherules and are characterized by the skeletal nature of their olivine phenocrysts.…”
Section: Resultsmentioning
confidence: 99%
“…Typically, coarse‐PO spherules contain significant interstitial glass (>10 vol%) and low vesicle abundances (<10 vol%) and include particles with cumulate textures described by Genge et al. (). Coarse‐skeletal PO spherules are the most abundant group in the Larkman Nunatak collection comprising 43.9% of PO spherules and are characterized by the skeletal nature of their olivine phenocrysts.…”
Section: Resultsmentioning
confidence: 99%
“…Previous studies on melted spherules have demonstrated that micrometeoroids can have both stable non‐spinning flights as well as flights with high spin rates (Genge et al [2016] and Genge 2017b). Evidence of stable flight histories includes cumulative settling of dense phases such as olivine and/or metal beads (Genge et al 2016), the floating of low‐density phases (i.e., vesicles) away from the particle’s leading front (Genge et al 2017), and the preservation of a coherent remnant magnetic field on cooling below the curie point (Suavet et al 2011). Spinning cosmic spherules appear rarer but are evidenced by hollow spherules containing a single large off‐center void (Suavet et al, 2011; Suttle and Folco 2020).…”
Section: Discussionmentioning
confidence: 99%
“…2A), this is evidence of orientated flight during atmospheric entry and demonstrates that the denser phases (olivine, metal and [fragments of the] intermetallic alloys) within the spherule migrated under gravitational force to the leading front of the particle. Furthermore, cumulate textures potentially indicate relatively high entry velocities (>16 kms −1 ), typical of highly eccentric orbits of dust released from the main and outer asteroid belt 43 . Thus, KT01 may have originated from either an asteroid in the middle or outer zone of the main belt.…”
Section: Discussionmentioning
confidence: 99%