Genge, Matthew J., van Ginneken, Matthias, Suttle, Martin D. (2020) Micrometeorites: Insights into the flux, sources and atmospheric entry of extraterrestrial dust at Earth. Planetary and Space Science, 187 . Article Number 104900. ISSN 0032-0633. (doi:10.1016/j.pss.2020.104900) (KAR id:88148)
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Official URL: https://doi.org/10.1016/j.pss.2020.104900 |
Abstract
Micrometeorites (MMs) provide constraints on the flux and sources of extraterrestrial dust falling on Earth as well as recording the processes occurring during atmospheric entry. Collections of micrometeorites have been recovered from a wide variety of environments including Antarctic moraine, rock traps, ice and snow and on roof tops in urban areas. Studies of the mineralogy and composition of MMs suggest that most particles (>98%) >50 μm in diameter have asteroidal sources, whilst ~50% of particles smaller than 50 μm are likely to be derived from comets. The relative abundance of S(IV)-type asteroid materials, similar to ordinary chondrites increases with size, although C-type asteroidal materials, similar to carbonaceous chondrites dominate over all. Although MMs provide excellent evidence on the nature and abundance of extraterrestrial dust at the Earth’s orbit they are not without bias and uncertainty. Mineralogical and compositional change during atmospheric entry makes the exact nature of their precursors uncertain complicating evaluation of source beyond basic classes of material. This is particularly true at larger sizes when complete melting to form cosmic spherules occurs, however, unmelted MMs >50 μm in size are also often thermally altered. Mixing with atmospheric oxygen and mass fractionation by evaporation furthermore complicates the use of oxygen isotope compositions in identifying parent bodies. All MM collections are suggested to exhibit biases owing to: (1) collection method, (2) terrestrial weathering, (3) terrestrial contamination, and (4) erosion and deposition by terrestrial surface processes. Even in the least biased collections, those collected by dedicated melting of Antarctic snow, erosive loss of material is suggested here to make fluxes uncertain by factors of up to ~2. The abundance of asteroid-derived MMs observed in collections contradicts models of the orbital evolution of interplanetary dust to Earth, which suggests >70% should be provided by comets.
Item Type: | Article |
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DOI/Identification number: | 10.1016/j.pss.2020.104900 |
Uncontrolled keywords: | Micrometeorites; Meteors; Interplanetary dust; AsteroidsComets |
Subjects: | Q Science > QE Geology > QE515 Geochemistry |
Divisions: | Divisions > Division of Natural Sciences > Physics and Astronomy |
Funders: | Science and Technology Facilities Council (https://ror.org/057g20z61) |
Depositing User: | Matthias van Ginneken |
Date Deposited: | 14 May 2021 13:58 UTC |
Last Modified: | 21 Sep 2022 15:44 UTC |
Resource URI: | https://kar.kent.ac.uk/id/eprint/88148 (The current URI for this page, for reference purposes) |
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