Formation of Continental Crust by Diapiric Melting of Recycled Crustal Materials in the Mantle Wedge

Abstract

Continental crust (CC) provides the long-term record of origin and evolution of Earth's lithosphere, atmosphere, hydrosphere, and biosphere (Cawood et al., 2013). On the modern Earth, and since the commencement of plate tectonics, the CC is interpreted to be extracted primarily by subduction-related magmatism from the mantle (Rudnick, 1995) in accretionary orogens (Cawood et al., 2009). However, this raises a well-known paradox of CC formation that mantle-derived melts are generally basaltic and differ from CC, which has an overall andesitic-dacitic composition (Figure 1a; Rudnick & Gao, 2014). Resolving this discrepancy has proven to be a challenge, and three models are generally invoked: (a) delamination of mafic/ultramafic rock of lower crust into the mantle (