Figure F2. Schematic drawings of crustal accretion models (modified from Korenaga and Kelemen, 1997). Black arrows = movement of the crystal mush, blue arrows = dominant zones where hydrothermal circulation removes latent and sensible heat. A. Gabbro glacier in which the lower oceanic crust crystallizes in a thin magma lens at the base of the sheeted dike complex from which cumulates subside downward and outward to form the lower crust (e.g., Henstock et al., 1993; Phipps Morgan and Chen, 1993; Quick and Denlinger, 1993). B. Hybrid model in which some crystallization occurs in an upper melt lens and some within sill-like bodies in the lower crust (e.g., Boudier et al., 1996). C. “Sheeted” or “stacked” sill model in which the lower ocean crust forms by crystallization of multiple sill-like intrusions (e.g., Bédard et al., 1988; Kelemen and Aharonov, 1998; Kelemen et al., 1997).
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