Arc Magmatism Controlled by Switches in Tectonic Style: Insights From the NE Asian Margin in the Cretaceous

Abstract

Abstract A relation between tectonics and arc magmatism has been proposed in the west Pacific‐type accretionary orogens, but the specific mechanism remains unclear. This study examines the Cretaceous records in NE Asia in order to unravel this link. Two tectono‐magmatic episodes, namely the Early and Late Cretaceous, are recognized. The first episode was under (trans‐)extension, consisting of both mafic and felsic, depleted and enriched, and deep‐ and shallow‐derived arc magmas. The second episode experienced several compressive events with highly evolved and shallow‐derived (mid‐crustal level) arc magmas. We propose that (trans‐)extension thinned the arc crust, facilitating deep mafic magmas to ascend and cool rapidly, maintaining their geochemical diversity. Compression led to magmatic emplacement around the middle crust; and the warm crust allowed highly‐evolved granitoids to form. Therefore, tectonic setting controls arc magmatism in NE Asia, and is likely representative of other west Pacific‐type orogens.