Thermal alteration of CM carbonaceous chondrites: Mineralogical changes and metamorphic temperatures

Petrographic, chemical and spectroscopic evidence for thermal metamorphism in carbonaceous chondrites I: CI and CM chondrites

We present a comprehensive description of petrologic, chemical and spectroscopic features of thermally metamorphosed CI-like and CM (and CM-like) chondrites. Only two such CI chondrites have so far been discovered i.e. Y-86029 and Y82162. Thermal metamorphism in these chondrites is apparent in their low contents of H2O, C and the most thermally labile trace elements, partial dehydration of matr...

The Role of Microchemical Environments in the Alteration of Cm Carbonaceous Chondrites

Introduction: Aqueous fluids have left their fingerprint on almost all the known chondrite groups and attest to the fact that water was a widespread agent of change in the early solar system [1,2]. The interaction of liquid or gaseous water with the primary products of nebular processes caused significant textural, mineralogical, compositional and isotopic changes that are often very complex to...

Early Alteration of Matrices in Parent Bodies of Ci/cm Carbonaceous Chondrites: Kinetic-thermodynamic Modeling

Modeling Aqueous Alteration of Cm Carbonaceous Chondrites: Implications for Cronstedtite Formation by Water-rock Reaction

Introduction: CM carbonaceous chondrites display a wide range of aqueous alteration products that occurred by low temperature water-rock reactions on their parent bodies [1,2]. Previous modeling studies have verified that these reactions occurred at low temperatures (0-50C), for they reproduced many of the observed mineral assemblages [3]. The dominant phases are tochilinite and Mg-Fe phyllosil...

Thermal Metamorphism of Cm Carbonaceous Chondrites: Effects on Phyllosilicate Mineralogy and Presolar Grain Abundances

Introduction: CM carbonaceous chondrites have been constituent materials of hydrated planetesimals in the early solar system. They consist mainly of hydrous minerals as a result of extensive aqueous alteration. At a certain period after the aqueous alteration, many CM chondrites have been heated to higher temperature [e.g., 1], which caused evaporation loss of highly volatile elements [2] and d...