Resolving the crustal composition paradox by 3.8 billion years of slab failure magmatism and collisional recycling of continental crust

摘要: Abstract In the standard paradigm, continental crust is formed mainly by arc magmatism, but because compositions of magma rising from mantle are basaltic and estimated to contain about 60% SiO2 much less MgO than basalt, two do not match. To resolve this paradox, most researchers argue that large amounts magmatic fractionation produce residual cumulates at base crust, which arcs inferred have magmatically thickened form eclogites ultimately founder sink into mantle. Not only there problems with contrasting bulk compositions, model also fails prior collision modern thick as documented their eruption close sea level, in cases ancient sequences, intercalation marine sedimentary rocks. Our study Cretaceous batholiths North American Cordillera resolves crustal composition paradox we find arc-derived commonly believed; instead during waning stages consequent slab failure. Because typically silica contents >60% derived directly mantle, they missing link formation crust. Slab failure magmas worldwide compositionally similar tonalite-trondhjemite-granodiorite suites old 3.8 Ga, points collective long-lived plate tectonics. provides (1) an alternative solution interpret compiled detrital zircon arrays, episodic peaks coincide periods supercontinent amalgamation easily interpreted represent collisions new failure; (2) models early whole-earth differentiation more reasonable those invoking progressive growth