Fig. 4: Mantle thickness comparison between results from decompressional melting modeling and observations from the Kangjinla ophiolitic section.

Variations of partial melting degrees (F) versus pressure (P, kbar) for the isentropic decompressional melting residues (a), and F versus distance from the north end (m) for the Kangjinla peridotites (b). F in a was acquired by thermodynamic modeling as shown in Fig. 3, while F in b was calculated using spinel Cr# and the updated equation (F = 9*ln(Cr#)+23)¹³. Petrological column shown in b is the same as those shown in Fig. 1d. Gray zones in a and b mark the mantle “depletion” extents of the Kangjinla peridotites, and indicate the required pressure differences produced by the isentropic decompressional fractional melting in a.