Aqueous alteration of chondrules from the Murchison CM carbonaceous chondrite: Replacement, pore filling, and the genesis of polyhedral serpentine

Serpentinisation of Chondrules in the Murchison Cm Carbonaceous Chondrite by Centripetal Replacement and Cementation

Elephant Moraine 96029, a very mildly aqueously altered and heated CM carbonaceous chondrite: Implications for the drivers of parent body processing

Elephant Moraine (EET) 96029 is a CM carbonaceous chondrite regolith breccia with evidence for unusually mild aqueous alteration, a later phase of heating and terrestrial weathering. The presence of phyllosilicates and carbonates within chondrules and the fine-grained matrix indicates that this meteorite was aqueously altered in its parent body. Features showing that water-mediated processing w...

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...

Pristine Pre-accretionary Signatures in Cm Chondrite Silicates: a Common Parent-body with the Co Chondrites?

Introduction: The Mighei-like carbonaceous (CM) chondrites are one of the most abundant and aqueously altered group of carbonaceous chondrites [1–4]. The organic molecules present and the effects of aqueous alteration have been extensively studied in the CM chondrites [e.g., 1,3,5]. As many CM chondrites are extensively aqueously altered, the compositions and formation histories of their anhydr...

The paradox between low shock-stage and evidence for compaction in CM carbonaceous chondrites explained by multiple low-intensity impacts

Petrographic analysis of eight CM carbonaceous chondrites (EET 96029, LAP 031166, LON 94101, MET 01072, Murchison, Murray, SCO 06043, QUE 93005) by electron imaging and diffraction, and X-ray computed tomography, reveals that six of them have a petrofabric defined by shock flattened chondrules. With the exception of Murchison, those CMs that have a strong petrofabric also contain open or minera...