Large volcanic calderas, aka supervolcanoes, are enormous craters tens of kilometers in diameter produced by giant, explosive eruptions that rank among the most violent geologic events. Geophysical studies of recently active calderas and investigations of their eruption products suggest that their magmatic systems are driven by intrusion of mantle-derived basalt in the deep crust, a process commonly referred to as magmatic underplating.
However, direct confirmation of this connection and our understanding of the processes involved have been limited by lack of a crustal section exposing rocks deeper than about 5 km beneath a caldera.
In a new study published in the journal Geology, Quick et al. report evidence for a 285-million-year-old fossil caldera, more than 13 km in diameter, in northwest Italy, situated atop a tilted crustal section that was exposed by uplift and erosion to reveal the caldera's magmatic plumbing system from the surface to a depth of greater than 25 km.
This unprecedented exposure of magmatic plumbing provides a model for interpreting geophysical profiles and magmatic processes beneath active calderas, and direct confirmation of the cause-and-effect link between intrusion mantle-derived basalt in the deep crust and explosive volcanism.
- J.E. Quick, S. Sinigoi, G. Peressini, G. Demarchi, J.L. Wooden, and A. Sbis. Magmatic plumbing of a large Permian caldera exposed to a depth of 25 km. Geology, 2009; DOI: 10.1130/G30003A.1
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