Almost forgot Geochimica et Cosmochimica Acta for 1 Aug (vol. 402):
Eckart, L. M. Busemann, H. Krietsch, D. et al. Noble gases in CO chondrites: Primordial components, effects of parent body thermal alteration, and cosmic ray exposure ages P 104 .2025.04.021
Hewins, R. H. Zanetta, P-M. Leroux, H. et al. Accretion of the anomalous CR2 chondrite Northwest Africa 14674: Implications for the complexities of the CR parent bodies P 234 .2025.05.037
Quirico, E. Yabuta, H. Beck, P. et al. Co-evolution of organics and water in experimentally shocked Murchison and EET 90628 chondrites P 316 .2025.05.046
Again and again, I repeat myself: The majority of asteroids/meteorites (unmelted, “primitive” ones) preserve evidence from the dawn of the Solar System. In this month’s GeCoA, we see three examples, in three different meteorite groups. Starting with Eckart et al., we se noble gases (yes, inert gases) preserved and recovered from meteorites. These gases, precisely because they’re inert, are themselves untainted, primitive evidence. Eckart et al. specifically single out the CO group and its history.
And then we get to the CR chondrites. These carbonaceous chondrites formed in the outer Solar System, clearly. They broadly resemble the CI and CM chondrites, which by multiple lines of argument formed in a cool, wet place. And yet, the CRs are not CIs or CMs- why? Why are there three (…or more) types of rocks from the same place? And the meteorite NWA 14674 is, itself, not like the other CRs.
Speaking of cool and wet: these carbonaceous chondrites preserve water and organics from the early Solar System, itself from the presolar nebula, and also infalling from the broader galaxy. Yet the early Solar System was a wild place, rocks careening and crashing. Part of our understanding of these recovered water/organic samples is that they’re not-so-primitive; some are affected by impacts on their parent asteroids(/comets?). Quirico et al. do experimental astronomy, “crashing” meteorite materials.