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Nano-FTIR Investigation of the CM Chondrite Allan Hills 83100
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  • Jordan Young,
  • Timothy D. Glotch,
  • Mehmet Yesiltas,
  • Victoria E. Hamilton,
  • Laura Brucia Breitenfeld,
  • Hans A. Bechtel,
  • Stephanie Gilbert Corder,
  • Ziheng Yao
Jordan Young
Stony Brook University
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Timothy D. Glotch
Stony Brook University

Corresponding Author:[email protected]

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Mehmet Yesiltas
Kirklareli University
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Victoria E. Hamilton
Southwest Research Institute
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Laura Brucia Breitenfeld
Stony Brook University
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Hans A. Bechtel
Advanced Light Source Division, Lawrence Berkeley National Laboratory
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Stephanie Gilbert Corder
Lawrence Berkeley National Laboratory
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Ziheng Yao
Stony Brook University
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Abstract

Mid-infrared (MIR) spectroscopy has been used with great success to quantitatively determine the mineralogy of geologic samples. It has been employed in a variety of contexts from determining bulk composition of powdered samples to spectroscopic imaging of rock thin sections via micro-FTIR. Recent advances allow for IR measurements at the nanoscale. Near field nanoscale infrared imaging and spectroscopy with a broadband source (nano-FTIR) enable understanding of the spatial relationships between compositionally distinct materials within a sample. This will be of particular use when analyzing returned samples from Bennu and Ryugu, which are thought to be compositionally like CI or CM2 carbonaceous chondrites. Returned samples will likely contain olivine/pyroxene chondrules that have been transformed into hydrous phyllosilicates, sulfides, carbonates, and other alteration phases. The use of near-field infrared techniques to probe the boundaries between once pristine chondrules and alteration phases at the nanoscale is a novel approach to furthering our understanding of the compositional evolution of carbonaceous asteroids and the processes that drive their evolution. Here we report the results of nano-FTIR spectroscopy and imaging measurements performed on the carbonaceous chondrite Allan Hills (ALH) 83100 (CM1/2). We show with nanoscale resolution that spatially resolved Fe-Mg variations exist within the phylosilicates around a chondrule rim. We also present effects of crystal orientation on the nano-FTIR spectra to account for the spectral differences between the meteorite and mineral spectra.