Fig. 5: Petrography and oxygen isotopic and chemical compositions of anhydrous silicate minerals in Bennu samples (OREX-501054-0, OREX-501059-0, OREX-803114-0, OREX-800045-103 and OREX-800045-107).
From: The variety and origin of materials accreted by Bennu’s parent asteroid
a,b, Backscattered electron images of a chondrule-like olivine grain (Δ17O = −7‰; a) and an AOA-like olivine grain (Δ17O = −23‰; b). c, Oxygen isotopic compositions of individual olivine (Ol) and low-Ca pyroxene (Lpx). Oxygen isotopic compositions reflect three different groupings: a solar-like composition as found in primitive components of other CCs (CAIs and AOAs), a 16O-enhanced composition at Δ17O = −5‰ and a near-terrestrial (planetary) composition. TF, terrestrial fractionation line; CCAM, carbonaceous chondrite anhydrous mineral line; PCM, primitive chondrule mineral line (Methods). d, CaO contents (wt%) versus oxygen isotopic compositions (Δ17O) of olivine grains in Bennu (this study), Ryugu and the Ivuna CI chondrite33. The right panel is a histogram of Δ17O values in Bennu olivine grains. Error bars in c and d are 2 s.d. measurement errors.
