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Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming
Rejuvenation of previously intruded silicic magma is an important process leading to effusive
rhyolite, which is the most common product of volcanism at calderas with protracted
histories of eruption and unrest such as Yellowstone caldera (Wyoming), Long Valley caldera
(California), and Valles caldera (New Mexico) in the United States.
Although orders of magnitude
smaller in volume than rare caldera-forming supereruptions, these relatively frequent
effusions of rhyolite are comparable to the largest eruptions of the 20th century, and pose a
considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption
of silicic magma is unclear, particularly because the time between reheating of a subvolcanic
intrusion and eruption is poorly quantified.
This study uses nanometer-scale trace element
diffusion in sanidine crystals to reveal that rejuvenation of a near-solidus or subsolidus silicic
intrusion occurred in ∼10 mo or less following a protracted period (220 k.y.) of volcanic repose,
and resulted in effusion of ∼3 km3 of high-silica rhyolite lava at the onset of Yellowstone's last
volcanic interval. The future renewal of effusive silicic volcanism at Yellowstone will likely
require a comparable energetic intrusion of magma that remelts the shallow subvolcanic reservoir
and generates eruptible rhyolite on month to annual time scales.
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