Sodium-metasomatism in chondrules in CO3 chondrites: Relationship to parent body thermal metamorphism

Cryptic Metamorphic Effects in Chondrules from Highly Unequilibrated Ordinary Chondrites: an Insidious Parent-body Process

Introduction: Type 3 ordinary chondrites display a wide variety of metamorphic grades, ranging from little metamorphosed type-3.0 chondrites up to nearly equilibrated type 3.9's. Researchers commonly assume that pristine-looking chondrules found in the lowest petrological subtypes have been unaffected by metamorphic processes, and can be used to constrain pre-accretionary processes. Last year, ...

Oxygen Isotopes in Co3 Chondrites

Introduction: The results of a number of studies seem to indicate that CO3 chondrites can be subdivided into a metamorphic series analogous to that seen in ordinary chondrites [1,2,3]. It has been suggested that this sequence is the result of hydrothermal alteration on the CO parent body [4]. One particularly intriguing feature of CO3 chondrites is the reported general correlation between whole...

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...

Carbon and Oxygen Isotopes in Co3 Chondrites

Lithium Isotopic Analyses of Chondrites and Chondrules

Introduction: Light stable isotopes provide insights and constraints on nebular and parent body processes. Lithium isotope studies of chondrites offer such potential, with some specifically unique aspects. Lithium is monovalent, the lightest of nongaseous elements, it has a 15% mass difference between its 2 isotopes (Li and Li), it is fluid mobile, and it is one of the fastest diffusing element...