Fig. 3

IR absorption analyses of liquid inclusion residues and solid graphitic inclusions. (a) AFM-IR spectra recorded on and next to dried-up liquid inclusion residues in garnets (cf. Fig. 2 for locations). Two vibrational bands around 1280 cm^− 1 and 1660 cm^− 1 are readily apparent (even more so in the garnet background-subtracted spectra S1.1–S1.2 and S2.2–S2.1). The grey-shaded area indicates the region of the spectrum in which the OPO power significantly drops; the recorded intensities in this region thus carry no spectral information. (b,c) AFM-IR maps of absorption intensities at around 1280 cm^− 1 recorded on the dried-up liquid inclusion residues further show this signal is confined to the residues (cf. Fig. 2 for location; corresponding maps of 1660 cm^− 1 peak intensities are shown in Supplementary Fig. S4). O-PTIR map (d) of 1653 cm^− 1 IR absorption intensity shows how this signal is observed along a line of solid graphitic inclusions (see Supplementary Fig. S1a for location). IR absorption intensities in (b–d) are not to scale.