Magmatic Tempos in Large Hot Orogens in Comparison with Continental Margin Arcs.

Geochronologic data combined with a geographic information system-based spatial analysis of plutons in the Bohemian Massif, Variscan belt, allow us to describe the apparent magma fluxes and episodic temporal pattern of plutonism, different from the cyclic pattern of continental margin arcs. The former is interpreted as reflecting a secular thermotectonic evolution of the orogen and magma sources changing from mantle-dominated to intracrustal, paralleled by increasing significance of crustal recycling at the expense of crustal growth. The analysis also suggests that crustal thickening, commonly regarded as the main cause of plutonism in collisional orogens, may be of relatively lower significance than late-stage mantle delamination. [ABSTRACT FROM AUTHOR]

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