Abundance and importance of petrological type 1 chondritic material

Abstract

We review the mineralogy, petrology, and abundance of petrological type 1 extraterrestrial material. Such material has been completely altered by aqueous processing on its parent bodies. As well as the four meteorite groups that contain type 1 members (CI, CM, CR, and CY), we summarize data from the 2019 fall Flensburg and a recent reanalysis of the "meteorite" Bench Crater found on the Moon, along with fine-grained micrometeorites, interplanetary dust particles, and xenoliths in meteorites. Type 1 materials exhibit a remarkably high diversity of alteration conditions (temperature, water-to-rock [W/R] ratios, and fluid composition) and starting mineralogy. Type 1 material comprises a significant component of the modern extraterrestrial flux to the Earth and was likely common throughout the solar system during the whole course of its history, pointing to both widespread accretion with ices and heating of parent bodies. Type 1 materials are composed predominantly of various phyllosilicates, carbonates, sulfides, and magnetite. Some type 1 materials appear to be part of a "CM clan" typified by serpentine-rich phyllosilicate compositions and an oxygen isotope composition that falls in the 16 O-rich part of the CM field. Others span a wide range in d 18 O (>30&) and fall on or above the terrestrial fractionation line (+ve D 17 O). Positive D 17 O values are unusual for carbonaceous meteorites but are relatively common in type 1 materials. The wide variation in oxygen isotopes, as well as in textures, mineralogy, and bulk chemistry, points to multiple parent bodies that may originate in the inner and/or outer solar system. Cometary materials, or transition objects such as Main Belt comets or type D asteroids, are likely the source of much of the type 1 materials on Earth but relating them to specific parents requires more study.

Incorporation of 16O-rich anhydrous silicates in the protolith of highly hydrated asteroid Ryugu

“…A total of 5.4 grams of surface and subsurface materials of the C-type asteroid 162173 Ryugu were collected by the Hayabusa2 spacecraft during its two touchdowns and then brought back to Earth on December 5 th , 2020. Initial characterization of these fragments at the JAXA curation facility revealed that Ryugu materials mineralogically resemble those of CI (Ivuna-type) chondrites 1,2 , an extremely rare meteorite group in our collections 11 . From a chemical perspective, CI chondrites are among the most primitive meteorites, having a bulk composition similar to that of the solar photosphere (e.g., ref 12,13 ).…”

“…From a chemical perspective, CI chondrites are among the most primitive meteorites, having a bulk composition similar to that of the solar photosphere (e.g., ref 12,13 ). However, paradoxically, they also contain very high abundances of mineral phases (e.g., carbonates, magnetite, phyllosilicates, and sul de) produced by extensive interactions between water and the original mineralogy on their parent asteroids (e.g., refs 11,14 ). Despite having a solar-like bulk elemental composition, the CI chondrites are the furthest of all carbonaceous chondrite meteorites from the solar value in terms of oxygen isotopes (e.g., ref 15 ).…”

Extended time scales of carbonaceous chondrite aqueous alteration evidenced by a xenolith in LaPaz Icefield 02239 (CM2)

“…Analyses of the matrix areas were subjected to much higher 16 OH À signal than the olivine and pyroxene Note: Clasts with a C1 affinity are commonplace in the CMs but rarely recorded (Russell et al, 2022). a Kerraouch et al (2021).…”

Xenon in the Protoplanetary Disk (PPD), in Two Planets, and a Comet

“…As Pepin has shown in several reports, an extrapolation to a primitive reservoir using fission-corrected atmospheric Xe data and hydrodynamic fractionation models to obtain the primitive composition U-Xe (Table 2), that differs slightly from Xe-PR(-5), specifically in the case of isotope 124 Xe. Evolution of terrestrial Xe since Archean times, as proposed by Avice et al (2017Avice et al ( , 2018, or continuing accretion of Type I carbonaceous volatile-rich matter (Russell et al 2022) are possible explanations. Many relevant questions like timing and mechanisms of fractionation processes also require further investigations.…”

“…Now we consider another apparently novel Xe isotopic pattern reported by King et al (2019) in Yamato carbonaceous (CY) chondrites. These carbonaceous chondrites originate from a distinct parent body that shows a distinct and heavy oxygen isotopic signature on the terrestrial fractionation line (Russell et al 2022). King et al (2019) reported noble gas data, including Xe, and concluded that the CY samples show varying degrees of aqueous alteration and might present possible analogs for asteroid Ryugu.…”