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. 2019 Nov 20;5(11):eaax5078. doi: 10.1126/sciadv.aax5078

Fig. 3. STEM-EDS maps and chemical and oxygen isotopic compositions of UPL and the matrix.

Fig. 3

An annular dark field (ADF)–STEM image (A) and a combined STEM-EDS map (B) for Fe (red), Mg (green), Si (blue), and S (yellow) show that both UPL and the matrix consist mainly of amorphous silicates (Amo; magenta), forsterite (Fo; light green), enstatite (En; cyan), and Fe─Ni sulfides (Sulf; yellow). Spongy organics (OM; red) (C) are heterogeneously distributed in the UPL. Compositions of GEMS-like materials (Amo + Sulf) in the UPL and the matrix, plotted in the Si─Mg─Fe diagram (D), are relatively homogeneous and enriched in Fe compared with those of GEMS in CP-IDPs (1, 3, 4). Olivine (Ol), pyroxene (Px), and serpentine (Serp) solid solution lines are also shown in (D). at %, atomic %. The oxygen isotopic compositions of UPL and the matrix are plotted in the oxygen three-isotope diagram (E). GEMS-like materials in UPLs and the matrix plot around the GEMS (2) mass fractionation (GF) line, suggesting their similar origins. The constituents in UPLs and the matrix show relatively heavy-oxygen isotopic compositions compared with the bulk meteorite (15). SMOW, standard mean of ocean water; TF, terrestrial mass fractionation line; CCAM, carbonaceous chondrite anhydrous mineral line.