Extended Data Figure 1: Comparison of experimental compositions with natural rocks.
a–f, ‘Fresh’ MORB rocks (red field), ALL-MORB21 (red circle), altered MORB rocks41 (pale blue circles), exhumed blueschist, greenschist and/or eclogitic rocks (yellow circles) and starting material from this (dark blue circle) and previous studies (green circles) of carbonated MORB compositions. In a, rocks altered MORB and exhumed rock compositions that fall on the Mg-Fe side of the maj–cpx join from Extended Data Fig. 5 plot below the dashed line, compositions that lie on the Ca side of this join are plotted as orange circles with yellow outlines or purple circles with blue outlines and sit above the dashed curve. This confirms that magnesite will be the stable carbonate phase at high pressure in the vast majority of natural crustal rocks, as is the case for ATCM1. Data and corresponding references for this figure are provided in the online source data file.
