Generation of Continental Lithospheric Mantle by Tectonic Isolation of Oceanic Plate

Abstract Continental formation models invoke subduction or plume‐related processes to create the buoyant, refractory character of continental lithospheric mantle (CLM). From similarities in melt depletion, major element composition, modal clinopyroxene, and Os isotope systematics it has been proposed that oceanic lithosphere is likely protolith non‐cratonic CLM, however, a direct link between two difficult ascertain. Using dredged peridotite xenoliths from Ferrel Seamount, off west coast Baja California, Mexico, we show tectonic isolation an plate may lead CLM. are coarse‐grained spinel lherzolite, rare harzburgite. Bulk‐rock clinopyroxene trace compositions reveal two‐stages refertilization following with infiltration by mid‐ocean ridge basalt‐type melts, followed addition host alkali basalt. Melt depletion correlations 187 Os/ 188 highly siderophile abundances indicate preserved ancient. these observations, represent abandoned Pacific‐Farallon ridge. The history MORB‐melt consistent peridotites representing was subsequently incorporated into Baja‐Guadalupe microplate during “ridge jump.” These demonstrate rafted onto margin provides viable means for producing We suggest continuation late‐stage, low degree provide CLM propose model preserve facilitate this continued evolution.