Article
Continental crustMantle transition
zoneDisintegrated
slabs1,400 1,600 2,000 2,400 2,600 2,800 3,000 3,200Depth, kmDepth, km1,800 2,0002006004000500300100b2006004000Distance, km500300100aMantle transition
zone Disintegrated slabsContinental crustOceanic crustOceanic crust5 сm/yr5 сm/yrPartially molten
mantleDiapirsDiapirs T=250 oC
18.2 myrs T=250 oC
19.8 myrsMantle
protokeelMantle
protokeelExtended Data Fig. 3 | Termination of the protokeel detachment from the
slab after the beginning of arc-continent collision. The evolution of the
experiment shown in Fig. 2a, b is shown (40-Myr-old lithosphere, subducting
plate velocity of 5 cm yr−1, elevated mantle potential temperature (Tp = 1, 550 °C,
ΔT = 250 °C)) for longer experiment run times. a, Growth of basaltic arc on the
former oceanic crust at 18.2 Myr ago. b, Growth of the arc composed of basaltic
and felsic volcanic rocks derived by f luid-f luxed melting of the mantle wedge
and melting of the hydrated slab, respectively, at 19.8 Myr ago. We note the
preservation of the protokeel thickness and its underplating by hydrated
diapirs derived from slab fragments. The reduced degree of decompression
melting (narrow red zones) is due to the strong upper mantle depletion. The
colour key is shown in Fig. 1. The protokeel source mantle (T > 1,300 °C, melt
depletion >20%) under the subducting plate is outlined in magenta for better
visibility.