Fig. 1.

Oxygen three-isotope diagram of bulk and chondritic components from CM and CO chondrites. The CCAM (carbonaceous chondrite anhydrous mineral; Clayton et al., 1977), Y&R (Young and Russell, 1998), and PCM (primitive chondrule minerals; Ushikubo et al., 2012) lines are shown for reference. The terrestrial fractionation line (TFL) is also shown. CM2 bulk data include falls data from Clayton and Mayeda (1999) and the two falls Sayama (Grossman and Zipfel, 2001) and Maribo (Haack et al., 2012). Both altered and less altered lithologies from the CM2 Paris are reported (Hewins et al., 2014). CM2 matrices and CO3 bulk falls are from Clayton and Mayeda (1999) and Greenwood and Franchi (2004), respectively. The Murchison-anhydrous data are from anhydrous mineral separates of the Murchison CM2 chondrite (Clayton and Mayeda, 1984). Y-81020 data are SIMS olivine and pyroxene analyses from chondrules in the Yamato 81020 CO3.0 chondrite (Tenner et al., 2013). The dashed line indicates the linear regression through the oxygen isotope data for the CM2 bulk compositions, Paris, and the anhydrous mineral separates of Murchison.