Peridotites deformed pyroxenites

Figure 27 Occurrences of isoclinally folded and boudinaged mafic layers in the Beni Bousera otogenic peridotite, northern Morocco, after Allegre and Turcotte, 1986 reproduced by permission of Nature Publishing Group from Nature, 1986, 323, 123-127. In their marhle cake model, Allegre and Turcotte interpret these mafic layers as subducted oceanic lithosphere—modified by partial melting and metamorphism—that was stirred, stretched, and thinned by mantle convection (see, also, Kornprobst et al., 1990 Blichert-Toft et al., 1999). For Pearson et al. (1993), these pyroxenites would rather derive from crystallization products of partial melts from subducted crust. They would have been emplaced as dikes in the hanging wall of a subduction zone and deformed during the exhumation of the...

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