Inside the volcano: Three-dimensional magmatic architecture of a buried shield volcano

The nature and growth of magmatic plumbing systems are of fundamental importance to igneous geology. Traditionally, magma chambers have been viewed as rapidly emplaced bodies of molten rock or partially crystallized magma mush connected to the surface by a narrow cylindrical conduit (referred to as the balloon-and-straw model). Recent data suggest, however, that magma chambers beneath volcanoes are formed incrementally through amalgamation of smaller intrusions. Here we present the first high-resolution three-dimensional reconstruction of an ancient volcanic plumbing system as a large laccolithic complex. By integrating seismic reflection and gravity data, we show that the similar to 200 km(3) laccolith appears to have formed through partial amalgamation of smaller intrusions. The complex appears to have fed both surface volcanism and an extensive sill network beneath the volcanic edifice. Numerous sills are imaged within the volcanic conduit, indicating that magma stalled at various levels during its ascent. Our results reveal for the first time the entire multicomponent plumbing system within a large ancient shield volcano.

Automated summary

This study presents the first high-resolution three-dimensional reconstruction of an ancient volcanic plumbing system, revealing a large laccolithic complex formed incrementally through amalgamation of smaller intrusions. Seismic reflection and gravity data show that the complex fed surface volcanism and an extensive sill network, with numerous sills indicating magma stalling at different levels during ascent. This research provides insight into the multicomponent plumbing system within a large ancient shield volcano for the first time.