Spectral Effects of Heating C3.00-Ungrouped Chwichiya 002 and Other Type 3 Carbonaceous Chondrites Under Vacuum

Abstract

Three petrological type-3 carbonaceous chondrites; C3.00-ungrouped Chwichiya 002, CV3ox NWA 14743, and CK3 NWA 15337 were heated under vacuum up to 700℃. Additionally, carbonaceous chondrite matrix constituents: saponite and serpentine were also heated under the same conditions up to 900℃. Bi-directional reflectance spectroscopy data were collected under vacuum. The spectra show variability in their albedo as temperature increases. Measurements were made using a Bruker 80v FTIR spectrometer, at a resolution of 4 cm-1, relative to Spectralon and InfraGold in the VISNIR and IR, respectively. The 2.7 µm OH-associated absorption feature remains consistent in the meteorites, whereas the phyllosilicates display a gradual weakening of the same feature. The aromatization and volatilization of carbon, organic matter, and opaques such as sulfides could explain the increase in albedo observed. As heating ensues, the reaction of primary silicates with evolved water could lead to deepening and the persistence of the 2.7 µm band in the meteorites. The characterization of the spectral properties of the primitive carbonaceous chondrites presented in this study could help understand and interpret future experiments and help establish any links to parent-body asteroids.