Madison Myers says new evidence from Yellowstone supervolcano rocks points to the Lava Creek Tuff eruption unfolding in several closely spaced pulses, not one blast. In the Yellowstone Caldera Chronicles, she writes that the field evidence should make readers "put on your boots and don’t forget your hand lens!"
The rocks come from the Sour Creek dome, just north of Yellowstone Lake, where field geologists have spent over the past 5 years remapping deposits and comparing them with argon dating results. Myers, an Associate Professor with the Department of Earth Sciences at Montana State University, says that work shows some deposits erupted one after another and that several rocks contain fragments of earlier erupted material that had already cooled and solidified before being torn up and re-erupted.
Sour Creek dome rocks
Rocks in the Sour Creek dome turned out to be younger than previously mapped, and some were the same age as Yellowstone Caldera after argon dating methods were used. The dome is a resurgent dome formed by magma injection at shallow depths, and it is thought to be driven by repressurization of the magma body that erupted the Lava Creek Tuff and formed Yellowstone Caldera.
That result changes the old picture of the Lava Creek Tuff eruption, which had been interpreted as just two main pulses, members A and B. Myers says the new evidence points instead to a sequence rather than a single event, with numerous smaller pulses spread over weeks to decades to centuries.
Yellowstone Caldera sequence
The eruption itself happened roughly 631,000 years ago, and Yellowstone Caldera formed soon after. The revised reading does not just rename the layers; it changes how the sequence is reconstructed, because the same-age rocks and recycled fragments show that the eruption record at Sour Creek dome preserved repeated activity rather than one abrupt release.
For researchers studying Yellowstone, the open issue is how precisely those eruptive pulses unfolded in time. The new field work narrows the answer to a multi-pulse sequence, but the spacing between the pulses still sets the timing of the full Lava Creek Tuff eruption history.
