Yellowstone's volcanism is the most recent in a 17 million-year history of volcanic activity that progressed from southwest to northeast along the Snake River Plain.
Hot spot volcanism is responsible for Yellowstone eruptions.
Yellowstone's volcanism is the most recent in a 17 million-year history of volcanic activity that progressed from southwest to northeast along the Snake River Plain. A track of volcanic complexes can be traced for more than 750 km (450 mi) and marks the surface manifestation of hot spot volcanism where a plume of mantle material rises into the crust, is stored, then erupts. Similar to today's Yellowstone Plateau Volcanic Field, at least six other large volcanic centers along this path generated multiple caldera-forming eruptions. The calderas are no longer visible because they are buried beneath younger basaltic lava flows and sediments that blanket the Snake River Plain. Eruptions from each of the volcanic centers lasted a few million years before crustal movement reoriented the center of magmatic activity. There was a 2.3-million-year hiatus between the last significant caldera-forming event in the adjacent and older Heise Volcanic Field, and the inception of volcanic activity in the modern Yellowstone Plateau.
Yellowstone Plateau Volcanic Field evolved as three repeat cycle.
Three extraordinarily large explosive eruptions in the past 2.1 million years each created a giant caldera within or west of Yellowstone National Park. During these eruptions, enormous volumes of hot, fragmented volcanic rocks spread outward as pyroclastic density currents over vast areas. The hot ash, pumice, and other rock fragments accumulated and welded together to form extensive sheets of hard lava-like rock. In some sections, these welded ash-flow tuffs are more than 400 m thick! These ash-flow sheets—from oldest to youngest, the Huckleberry Ridge, Mesa Falls, and Lava Creek Tuffs—account for more than half the material erupted from Yellowstone in the past 2.1 million years. Because such enormous amounts of magma were erupted during each explosive event, the roof of the magma-storage regions collapsed, and the ground above subsided by many hundreds of meters to form the calderas.
|Caldera-forming ash-flow tuff||Age (millions of years)||Volume erupted (km3)||Area covered (km2)||Caldera dimensions (km)||Caldera name|
|Lava Creek Tuff||- 0.640||1,000||7,500||85 x 45||Yellowstone caldera|
|Mesa Falls Tuff||-1.3||280||2,700||16 km in diameter||Henry's Fork caldera|
|Huckleberry Ridge Tuff||-2.1||2,450||15,500||75-95 x 40-601||Big Bend Ridge, Snake River, and Red Mountains caldera segments|
1Inferred first-cycle caldera boundary is irregular; caldera consists of three overlapping collapse areas.
Before and after these caldera-forming events, eruptions in the Yellowstone area produced rhyolitic and basaltic rocks—large rhyolite lava flows and some smaller pyroclastic flows in and near where the calderas collapsed and basalt lava flows around the margins of the calderas.
The most recent eruptions were thick lava flows.
Large volume rhyolitic lava flows (approximately 600 km3 (144 mi3) were erupted in the caldera between 180,000 and 70,000 years ago, distributed primarily along two north-south alignments of vents.
Aerial view of the striking NW rim of the Yellowstone caldera and intracaldera rhyolite lava flows at Madison Junction in Yellowstone National Park. View is looking north. The steep-facing caldera wall, 500 m tall, formed when the area in the foreground collapsed during eruption of the Lava Creek Tuff 640,000 years ago. The thick West Yellowstone rhyolite lava flow erupted about 110,000 years ago, and the Nez Perce Creek flow erupted 160,000 years ago.