Extended Data Fig. 5: Raman spectra for inclusion 2c at different areas (a-d).

Coesite (cs) peaks (RRUFF ID: X050094⁶⁷) have been observed in almost all spectra; the peaks in area (a) and (c) at ~800 and 858 cm⁻¹ are assigned to ringwoodite (rw) or partially retrogressed olivine (ol), possibly accompanied by enstatite (En) in (a). Diagnostic Raman peaks have been observed in (b) at ~787, 735, 626, 375 cm⁻¹, which could be assigned to phase D (D). The accompanied vibration at ~2849 cm⁻¹ in (b) is consistent with the OH stretching of phase D^23,68,69. A few peaks at ~781 and 735 cm⁻¹ seem recurring in (d). Spectra were collected at GIA. Red circle, triangle, orange stars: undefined peaks. The orange stars with the peak around 831 cm⁻¹ could be overlapped with other hydrous phase such as super hydrous phase B^70,71.