Rudraswami, NG, Shyam Prasad, M, Dey, S et al. (5 more authors) (2016) Relict of Olivines in Micrometeorites: Precursors and interactions in the Earth's atmosphere. Astrophysical Journal, 831 (2). ISSN 0004-637X
Abstract
Antarctica micrometeorites (~1200) and cosmic spherules (~5000) from deep sea sediments are studied using electron microscopy to identify Mg-rich olivine grains in order to determine the nature of the particle precursors. Mg-rich olivine (FeO < 5wt%) in micrometeorites suffers insignificant chemical modification during its history and is a well-preserved phase. 420 forsterite grains enclosed in 162 micrometeorites of different types - unmelted, scoriaceous and porphyritic - are examined in this study. Forsterites in micrometeorites of different types are crystallized during their formation in solar nebula; their closest analogues are chondrule components of CV-type chondrites or volatile rich CM chondrites. The forsteritic olivines are suggested to have originated from a cluster of closely related carbonaceous asteroids that have Mg-rich olivines in the narrow range of CaO (0.1−0.3 wt%), Al2O3 (0.0−0.3wt%), MnO (0.0−0.3wt%) and Cr2O3 (0.1−0.7wt%). Numerical simulations carried out with the Chemical Ablation Model (CABMOD) enable us to define the physical conditions of atmospheric entry that preserve the original compositions of the Mg-rich olivines in these particles. The chemical compositions of relict olivines affirm the role of heating at peak temperatures and the cooling rates of the micrometeorites. This modelling approach provides a foundation for understanding the ablation of the particles and the circumstances in which the relict grains tend to survive.
Metadata
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Copyright, Publisher and Additional Information: | © 2016. The American Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Keywords: | atmospheric effects, Earth, interplanetary medium , minor planets, asteroids: general, Sun: general | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Institution: | The University of Leeds | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Physical Chemistry (Leeds) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Depositing User: | Symplectic Publications | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Date Deposited: | 09 Sep 2016 12:39 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Last Modified: | 05 Oct 2017 16:11 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Published Version: | https://doi.org/10.3847/0004-637X/831/2/197 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Status: | Published | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Publisher: | American Astronomical Society | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Identification Number: | https://doi.org/10.3847/0004-637X/831/2/197 |