A high-resolution in situ X-ray diffraction study of mineral transitions due to post-hydration heating in CM chondrite meteoritesOPEN ACCESS 

· by · in , , ,

Laura E. Jenkins, Ashley J. King, Martin R. Lee, Luke Daly, Stephen P. Thompson, Sarah J. Day, Lucy Saunders, Pierre-Etienne Martin & Fahkri Bintang

Earth, Planets and Space, Volume 76, article number 172, Published: 26 December 2024

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“The effects of post-hydration heating over a broad range of temperatures are evident in many Mighei-like carbonaceous (CM) chondrites as a variety of mineral transitions. To better understand these processes and how a CM chondrite’s starting composition may have affected them, we experimentally heated two meteorites with different degrees of aqueous alteration, Allan Hills 83100 and Murchison, at 25 °C temperature steps from 200 °C to 950 °C and 300 °C to 750 °C, respectively. During heating, synchrotron in situ X-ray diffraction patterns were collected. With the exception of calcite decomposition and its products, most mineral transitions were unaffected by starting composition. Key observations include: (1) partial decomposition of tochilinite at 200 °C, which indicates that tochilinite breakdown might be a two-stage process due to its intergrown layers of brucite/amakinite and mackinawite; (2) the breakdown of serpentine occurring at 300 °C with transitional phases appearing at 525 °C and 575–600 °C, while secondary olivine formed at 600 °C; (3) cronstedtite decomposing faster than lizardite, (4) the formation of secondary enstatite at 750 °C, and (5) calcite decomposition temperature differing significantly between meteorites, occurring at 725 °C and 575 °C in ALH 83100 and Murchison, respectively. The results for calcite are likely controlled by differences in its microstructure and chemical composition, related to the meteorite’s impact history and degree of aqueous alteration. The difference in calcite decomposition temperature also explains the contrasts in the observed breakdown products, with clinopyroxene occurring in both meteorites, and oldhamite only in ALH 83100. Mineral transitions due to post-hydration heating have been characterized with a high resolution XRD method, enabling a better understanding of processes occurring on the parent asteroids of CM chondrites.”

Related posts (automatically generated):

  1. Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returnsOPEN ACCESS 
  2. Style and intensity of hydration among C-complex asteroids: a comparison to dessicated carbonaceous chondritesOPEN ACCESS 
  3. High-resolution cathodoluminescence of calcites from the Cold Bokkeveld chondrite: New insights on carbonatation processes in CM parent bodiesOPEN ACCESS 
  4. Spectral and mineralogical effects of heating on CM chondrite and related asteroids
  5. Fine-Grained Equant Troilite in the CM Chondrite Shidian: Potential Evidence for Low Temperature Post-Hydration Heating
  6. Kinetic analysis of dehydration/dehydroxylation from carbonaceous chondrites by in situ heating experiments under an infrared microscopeOPEN ACCESS 
  7. High‐mass resolution molecular imaging of organic compounds on the surface of Murchison meteorite
  8. Thermal history of matrix forsterite grains from Murchison based on high-resolution tomographyOPEN ACCESS 
  9. Thermal Metamorphism in the CM Parent Body — Evidence from Weakly Altered CM Chondrites LaPaz (LAP) 04565 and 02333
  10. High Resolution Micro Raman Spectroscopy on the Winchcombe Carbonaceous Chondrite (CM2)
Tags: , , , , , , , ,