Magmatic genesis, magmatic plumbing system, and geodynamic mechanism of Changbaishan volcanoes: New evidence from mineralogical, geochemical, and geothermobarometric data

Abstract

The Changbaishan volcanic field (mainly comprising Tianchi, Wangtian'e, Namphothe, and Tumen River volcanoes), located in the intraplate domain of the eastern Eurasian plate, has exhibited vigorous Cenozoic volcanism. However, the magmatic system and deep geodynamic mechanisms related to the volcanic activity underlying this active region remain controversial; namely, whether the magma originates from the mantle or subducted Pacific slab; whether the magma reservoir is multi- or single-layered with a large scale; and the source of the driving force of volcanic activity. In this study, we present an integrated analysis of newly acquired geochemical and geochronological data spanning all eruptive phases since the Pliocene, combined with existing datasets, and reconstruct the volcanic evolution of Changbaishan volcanic field. Geochemical results reveal homogeneous trace element patterns and Sr-Nd-Pb isotopic compositions across the Tianchi, Wangtian'e, and Tumen volcanic centers, indicating that the magma originated from an enriched mantle source formed by the mechanical mixing and fluid-melt metasomatism between the asthenosphere mantle and subducted Pacific slab components. Fractional crystallization is identified as the dominant magma differentiation mechanism. Mineral thermobarometers reveal a multi-tiered magma storage system, with shallow (ca. 3–5 km), intermediate (ca. 8–18 km), and deep-seated (ca. 25–36 km) reservoirs beneath Tianchi volcanoes. Moreover, the magma reservoirs of Wangtian'e volcano are located at depths of 8–15 and 25–36 km, contrasting with deeper magma sources (ca. 26–50 km) beneath the Tumen River volcano. These findings demonstrate that the stagnant Pacific slab in the mantle transition zone exerts fundamental control over regional volcanism through both material contributions and dynamic forces and resolves the genetic connections between surface volcanism and deep mantle processes. Furthermore, we also reconcile previous controversies regarding the origin of magma from the mantle and subducted Pacific slab with a multi-layered magma reservoir.