Model of mantle-crust interaction and magma generation in the suprasubduction orogen (Paleozoic of the Urals)

Abstract

A model of magma formation in the crust of the Urals mobile belt, which is the best example of epioceanic suprasubduction orogen, has been developed. Magma formation occurs both in the relic oceanic and in the newly formed orogen crust. In the first case small bodies of practically non-potassium plagiogranites are formed, in the second one can see large gabbro-tonalite-granodiorite-granite (GTGG) and essentially granite massifs. The main conclusion is that the formation of a new earth crust of the Urals mobile belt and magma generation in it was initiated by the replacement of low-water mantle magmatism with water-rich one. The latter accompanies crustal magma generation at all its stages. In the areas of intense water magmatism, centers of long-term (up to 100 million years or more) endogenous activity (CLEA) are formed, the products of which are GTGG and granite massifs. Two main stages are distinguished in the evolution of the CLEA: 1) spontaneous partial melting (automigmatization) of products of water-rich basic magmatism - hornblende gabbros and diorites, and formation of tonalite, granodiorite and plagiogranite melts; 2) partial melting of the tonalite and granodiorite which produces the melts of adamellitic and granite composition.

Keywords

• мантийно-коровое взаимодействие
• геодинамика
• магматизм
• мигматизация
• изотопия
• mantle-crustal interaction
• geodynamics
• magmatism
• migmatization
• isotopy