High Mg# of the continental crust explained by calc-alkaline differentiation.

ABSTRACT: We used compiled geochemical data to investigate the mechanisms that control Mg# (molar ratio of Mg/(Mg + Fe_T)) in andesitic arc lavas. We find that andesites from mature continental arcs with crustal thickness of >45 km have systematically higher Mg# than those from oceanic arcs with crustal thickness of <30 km. The elevated Mg# in continental arc lavas results from strong Fe depletion during high-pressure differentiation favored in thick crusts. This proposal is reinforced by our compiled melting/crystallization experiment data. We show that the Mg# characteristics of continental arc lavas match that of the continental crust. These findings suggest that the formation of many high-Mg# andesites and the continental crust may not require slab-melt/peridotite interactions. Instead

SUBMITTER: Tang M 

PROVIDER: S-EPMC9976743 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature