In the September issue of GSA TODAY Guillaume Girard and John Stix of McGill University in Montreal join the debate regarding future scenarios of intracaldera volcanism at Yellowstone National Park, USA.
Using data from quartz petrography, geochemistry, and geobarometry, Girard and Stix suggest that magma ascent during the most recent eruptions of intracaldera rhyolites occurred rapidly from depths of 8-10 km to the surface along major regional faults, without intervening storage.
They consequently predict that future volcanism, which could include large-volume lava flows and phreatomagmatic rhyolitic eruptions, has a higher probability of resuming along three fault-controlled NNW-trending lineaments on the western caldera rim and across the central and northeastern caldera.
The first two were the focus of recent (70,000 to 174,000 years ago) volcanism, while the last is the most active area of current caldera unrest.
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