Imperial College London
Alternate

DrMatthewGenge

Faculty of Engineering, Department of Earth Science & Engineering

Senior Lecturer in Earth and Planetary Science
 
 
 
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Contact

 

+44 (0)20 7594 6499m.genge

 
 
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Location

 

1.45Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Suttle:2017:10.1016/j.epsl.2017.07.052,
author = {Suttle, M and Genge, MJ},
doi = {10.1016/j.epsl.2017.07.052},
journal = {Earth and Planetary Science Letters},
pages = {132--142},
title = {Diagenetically altered fossil micrometeorites suggest cosmic dust is common in the geological record},
url = {http://dx.doi.org/10.1016/j.epsl.2017.07.052},
volume = {476},
year = {2017}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We report the discovery of fossil micrometeorites from Late Cretaceous chalk. Seventy-six cosmic spherules were recovered from Coniacian (87±1 Ma) sediments of the White Chalk Supergroup. Particles vary from pristine silicate and iron-type spherules to pseudomorphic spherules consisting of either single-phase recrystallized magnetite or Fe-silicide. Pristine spherules are readily identified as micrometeorites on the basis of their characteristic mineralogies, textures and compositions. Both magnetite and silicide spherules contain dendritic crystals and spherical morphologies, testifying to rapid crystallisation of high temperature iron-rich metallic and oxide liquids. These particles also contain spherical cavities, representing weathering and removal of metal beads and irregular cavities, representing vesicles formed by trapped gas during crystallization; both features commonly found among modern Antarctic Iron-type (I-type) cosmic spherules. On the basis of textural analysis, the magnetite and Fe-silicide spherules are shown to be I-type cosmic spherules that have experienced complete secondary replacement during diagenesis (fossilization). Our results demonstrate that micrometeorites, preserved in sedimentary rocks, are affected by a suite of complex diagenetic processes, which can result in disparate replacement minerals, even within the same sequence of sedimentary beds. As a result, the identification of fossil micrometeorites requires careful observation of particle textures and comparisons with modern Antarctic collections. Replaced micrometeorites imply that geochemical signatures the extraterrestrial dust are subject to diagenetic remobilisation that limits their stratigraphic resolution. However, this study demonstrates that fossil, pseudomorphic micrometeorites can be recognised and are likely common within the geological record.
AU  - Suttle,M
AU  - Genge,MJ
DO  - 10.1016/j.epsl.2017.07.052
EP  - 142
PY  - 2017///
SN  - 0012-821X
SP  - 132
TI  - Diagenetically altered fossil micrometeorites suggest cosmic dust is common in the geological record
T2  - Earth and Planetary Science Letters
UR  - http://dx.doi.org/10.1016/j.epsl.2017.07.052
UR  - https://www.sciencedirect.com/science/article/pii/S0012821X17304399
UR  - http://hdl.handle.net/10044/1/50285
VL  - 476
ER  -
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