Olivine settling in cosmic spherules during atmospheric deceleration: An indicator of the orbital eccentricity of interplanetary dust

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 1-2s of flight at high entry angles and entry velocities up to 16...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Genge, MJ, Suttle, M, Van Ginneken, M
Other Authors: Science and Technology Facilities Council (STFC)
Format: Article in Journal/Newspaper
Language:unknown
Published: American Geophysical Union 2016
Subjects:
Science & Technology
Physical Sciences
Geosciences
Multidisciplinary
Geology
cosmic spherules
ANTARCTIC MICROMETEORITES
EARTHS ATMOSPHERE
ASTEROID DUST
COLLECTION
MODEL
ICE
METEORITES
LIQUIDS
MELTS
Meteorology & Atmospheric Sciences
MD Multidisciplinary
Antarctic
Antarc*
Online Access:http://hdl.handle.net/10044/1/41298
https://doi.org/10.1002/2016GL070874
Description
Summary: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 1-2s of flight at high entry angles and entry velocities up to 16 km s-1. Enhanced crystallisation 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 spherules reveal interplanetary dust with higher encounter velocity with the Earth that correspond to orbital eccentricities >0.3. The relative abundance of cumulate spherules suggests 14% of ordinary chondrite-related, S(IV)-type asteroid dust over the last 800 kyr had relatively high orbital eccentricity owing to secular and planetary perturbations. The textures of cosmic spherules collected from sediments can therefore be used to trace dust orbital variations with time which may influence terrestrial climate.

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