Spectral reflectance properties of carbonaceous chondrites 4: Aqueously altered and thermally metamorphosed meteorites

Evidence for the effects of space weathering spectral signatures on low albedo asteroids

“…Albedo values are from IMPS data set (Tedesco et al 2004). In some asteroid spectra, there was a second band located around 0.9 μm (Cloutis et al 2011(Cloutis et al , 2012), however we did not find this band in the meteorite spectra (including laboratory altered meteorites). dots, meteorites are shown in squares and laboratory altered meteorites are shown in triangles and stars: heated and irradiated, respectively.…”

Spectral reflectance properties of carbonaceous chondrites: 8. “Other” carbonaceous chondrites: CH, ungrouped, polymict, xenolithic inclusions, and R chondrites

“…Comparison of these spectra indicates that the CM2-type inclusions in PRA 04401 cause reflectance to decrease. With increasing grain size, the PRA 04401 spectra become darker and more blue-sloped, consistent with the behavior of other CM2 spectra (Johnson and Fanale, 1973;Cloutis et al, 2012b). However, expected CM2-type absorption bands, near 0.7, and 1.1 lm are not apparent in the PRA 04401 spectra, even given its high CM2 abundance.…”

Modal mineralogy of CI and CI-like chondrites by X-ray diffraction

“…We note here that modal mineralogy in combination with infrared (IR) spectroscopy is helping to strengthen links between meteorites and their parent bodies (Beck et al, 2010McAdam et al, 2015). A significant fraction of C-type asteroids appear to have dehydrated surfaces with spectral features similar to those of the thermally metamorphosed CI-like chondrites (Hiroi et al, 1993(Hiroi et al, , 1996Osawa et al, 2005;Cloutis et al, 2012). The timing and mechanism of the thermal metamorphism remains poorly constrained, although studies of mineral textures (Nakato et al, 2008) and organics (Yabuta et al, 2010;Orthous-Daunay et al, 2013;Quirico et al, 2014) in the heated CM chondrites indicate that the process was short-lived and probably took place on the order of hours to several years.…”