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Can the magmatic conditions of the Martian nakhlites be discerned via investigation of clinopyroxene and olivine crystallographic slip-systems?
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  • Sammy Griffin,
  • Luke Daly,
  • Sandra Piazolo,
  • Lucy V Forman,
  • Benjamin E Cohen,
  • Martin Lee,
  • Patrick W Trimby,
  • Raphaël Baumgartner,
  • Gretchen K Benedix,
  • Ben Hoefnagels
Sammy Griffin
University of Glasgow

Corresponding Author:[email protected]

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Luke Daly
University of Glasgow
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Sandra Piazolo
School of Earth and Environment, The University of Leeds
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Lucy V Forman
Curtin University
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Benjamin E Cohen
University of Edinburgh
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Martin Lee
University of Glasgow
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Patrick W Trimby
Oxford Instruments
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Raphaël Baumgartner
Unknown
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Gretchen K Benedix
Curtin University
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Ben Hoefnagels
CityGIS
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Abstract

Deformation is a near ubiquitous process that is observed within nearly all naturally forming rocks, terrestrial and extra-terrestrial. Large area electron backscatter diffraction (EBSD) is a technique that enables slip-systems (a form of plastic deformation) to be inferred at a comparable scale to representative texture analysis (≥100 crystals). Extensive laboratory and studies on naturally occurring samples have identified preferential extrinsic parameters for specific slip-system signatures within olivine and clinopyroxene for mantle conditions. Slip-systems in both olivine and augite (high Ca-clinopyroxene) for 21 large area EBSD datasets sourced from 16 different Martian nakhlite meteorites were analysed and assessed against these parameters. When investigating the high and low deformation regions within the samples 10 of the 21 sections exhibited a shift in the slip-system patterns between the low and high deformation regions. The secondary signatures identified within the low deformation regions are inferred to relate to emplacement deformation. Thus, these samples exhibit both shock and emplacement signatures. The observed variations in deformation patterns for the two main regimes of deformation indicate heterogeneous sampling of the nakhlite ejecta crater. Our findings indicate that shock deformation is prevalent throughout the nakhlites, and that great care needs to be taken when interpreting slip-deformation of crystals within apparent lower deformation regions.