A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018.
Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent of granite.
Valles Caldera is a 13.7-mile (22.0 km) wide volcanic caldera in the Jemez Mountains of northern New Mexico. Hot springs, streams, fumaroles, natural gas seeps and volcanic domes dot the caldera floor landscape. The highest point in the caldera is Redondo Peak, an 11,253-foot (3,430 m) resurgent lava dome located entirely within the caldera. Also within the caldera are several grass valleys, or valles, the largest of which is Valle Grande, the only one accessible by a paved road. In 1975, Valles Caldera was designated as a National Natural Landmark by the National Park Service with much of the caldera being within the Valles Caldera National Preserve, a unit of the National Park System.
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrounding atmosphere. New Zealand geologist Patrick Marshall (1869–1950) coined the term ignimbrite from the Latin igni- [fire] and imbri- [rain].
The Bishop Tuff is a welded tuff that formed 764,800 ± 600 years ago as a rhyolitic pyroclastic flow during the approximately six day eruption that created the Long Valley Caldera. Large outcrops of the tuff are located in Inyo and Mono Counties, California, United States. Approximately 200 cubic kilometers of ash and tuff erupted outside the caldera.
The Jemez Mountains are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States.
Redondo Peak is a conspicuous summit in the Jemez Mountains of New Mexico, in the southwestern United States. It is located entirely within the Valles Caldera National Preserve. It is the second highest summit in the Jemez after Chicoma Mountain. It is the most visually prominent peak in the range when viewed from the south, for example, from Albuquerque. From many other directions it is less prominent or not visible, due to its location in the center of the Valles Caldera, well away from the caldera's rim.
The Pajarito Plateau is a volcanic plateau in north central New Mexico, United States. The plateau, part of the Jemez Mountains, is bounded on the west by the Sierra de los Valles, the range forming the east rim of the Valles Caldera, and on the east by the Puye escarpment, which rises about 300 to 400 feet above the Rio Grande valley about a mile (1.6 km) west of the river. The Rio Grande passes through White Rock Canyon to the southeast, and the Caja del Rio across the river is sometimes regarded as part of the plateau. The plateau is occupied by several notable entities, including Bandelier National Monument, the town of Los Alamos and its remote suburb White Rock, and Los Alamos National Laboratory. Elevations range from about 5,600 feet at the river to about 7,800 feet where the plateau merges into the mountain range.
The Lava Creek Tuff is a voluminous sheet of ash-flow tuff located in Wyoming, Montana and Idaho, United States. It was created during the Lava Creek eruption around 630,000 years ago, which led to the formation of the Yellowstone Caldera. This eruption is considered the climactic event of Yellowstone's third volcanic cycle. The Lava Creek Tuff covers an area of more than 7,500 km2 (2,900 sq mi) centered around the caldera and has an estimated magma volume of 1,000 km3 (240 cu mi).
La Garita Caldera is a large caldera in the San Juan volcanic field in the San Juan Mountains around the town of Creede in southwestern Colorado, United States. It is west of La Garita, Colorado. The eruption that created the La Garita Caldera is among the largest known volcanic eruptions in Earth's history, as well as being one of the most powerful known supervolcanic events.
The Jemez Lineament is a chain of late Cenozoic volcanic fields, 800 kilometers (500 mi) long, reaching from the Springerville and White Mountains volcanic fields in East-Central Arizona to the Raton-Clayton volcanic field in Northeastern New Mexico.
Caja del Rio is a dissected plateau, of volcanic origin, which covers approximately 84,000 acres of land in northern Santa Fe County, New Mexico, United States. The region is also known as the Caja, Caja del Rio Plateau, and Cerros del Rio. The center of the area is approximately 15 miles (23 km) west of Santa Fe, New Mexico. Most of the Caja is owned by the United States Forest Service and managed by the Santa Fe National Forest. Access is through New Mexico Highway 599, Santa Fe County Road 62, and Forest Service Road 24.
This timeline of volcanism on Earth includes a list of major volcanic eruptions of approximately at least magnitude 6 on the Volcanic explosivity index (VEI) or equivalent sulfur dioxide emission during the Quaternary period. Other volcanic eruptions are also listed.
Panizos is a Late Miocene caldera in the Potosí Department of Bolivia and the Jujuy Province of Argentina. It is part of the Altiplano-Puna volcanic complex of the Central Volcanic Zone in the Andes. 50 volcanoes active in recent times are found in the Central Volcanic Zone, and several major caldera complexes are situated in the area. The caldera is located in a difficult-to-access part of the Andes.
The Polvadera Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 13 to 2.2 million years, corresponding to the Miocene through early Quaternary.
The Keres Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 13 to 6 million years, corresponding to the Miocene epoch.
The Puye Formation is a geologic formation exposed east of the Jemez Mountains of northern New Mexico. Radiometric dating constrains its age to between 5 and 2 million years, corresponding to the Pliocene epoch.
The Tewa Group is a group of geologic formations exposed in and around the Jemez Mountains of northern New Mexico. Radiometric dating gives it an age of 1.85 million to 72 thousand years, corresponding to the Pleistocene epoch.
The Peach Spring Tuff is a pyroclastic flow sheet deposit spanning 32,000 km2 in California, Arizona, and Nevada. The source of the Peach Spring Tuff is the Silver Creek Caldera located outside of Oatman, AZ. The Silver Creek Caldera was found to be a match to the Peach Spring Tuff after an ignimbrite sample from within the caldera matched the phenocryst makeup and age of the Peach Spring Tuff. The caldera eruption is dated to the early Miocene, radiometrically dated to 18.78 +/- 0.02 Ma using argon-argon dating methods on sanidine crystals. The Peach Spring Tuff has a rhyolitic composition with thickness ranging from 10-140 m depending on location. The Peach Spring Tuff is the only geologic evidence of a super-eruption in this region.
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