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In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome , a resurgent dome is not formed by the extrusion of highly viscous lava onto the surface, but rather by the uplift and deformation of the surface itself by magma movement underground.
Caldera is the type locality for a resurgent dome caldera, the formation of which was first developed by C.S. Ross, R.L. Smith, and R.A. Bailey during field work at Valles in the 1960s. [19] This type locality and associated studies have been used to studied other resurgent domes around the world, including Yellowstone Caldera.
Although the Valles caldera is not unusually large, it is relatively young (1.25 million years old) and unusually well preserved, [31] and it remains one of the best studied examples of a resurgent caldera. [6] The ash flow tuffs of the Valles caldera, such as the Bandelier Tuff, were among the first to be thoroughly characterized. [32]
Such uplifts are common in very large calderas, apparently due to the upward pressure of below-ground magma. Toba is probably the largest resurgent caldera on Earth. Large earthquakes have recently occurred in the vicinity of the volcano, notably in 1987 along the southern shore of the lake at a depth of 11 km (6.8 mi). [29]
After the formation of the caldera, sediments and [14] tuffs within the caldera were uplifted [15] over an angular area of 350 square kilometres (140 sq mi), forming the 1 kilometre (0.62 mi) high resurgent dome known as Cordón La Pacana. [16] This resurgent dome is cut by numerous faults and features a poorly developed graben on its summit. [14]
The Yellowstone Caldera has two resurgent domes formed by magma upwelling called Sour Creek and Mallard Lakes. [8] The magma chambers under the Yellowstone Caldera provides heat and energy for large hydrothermal systems. [8] [9] The Yellowstone Caldera has the greatest concentration of hydrothermal features in the world, and is an active system ...
The field comprises four overlapping calderas, multiple lava domes, resurgent domes, crater lakes, and numerous bimodal lavas and tuffs of basaltic and rhyolitic composition, originally covering about 17,000 km 2 (6,600 sq mi). Volcanism began 2.15 million years ago and proceeded through three major volcanic cycles.
[10] [1] A tectonic block inside the caldera rises 700 metres (2,300 ft) above the rim of the caldera; it is a resurgent dome formed by welded tuff. [3] The highest point of the dome is 1,200 metres (3,900 ft). [9] Alternative theories are that La Reforma is a dome which was eroded to form a circular pattern or a set of tectonic blocks.