The 36-18 Ma Indian Peak-Caliente ignimbrite field and calderas, southeastern Great Basin, USA: Multicyclic super-eruptions

More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions. More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions. More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions. More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions. More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions. More than 50 ignimbrite cooling units, including 22 of regional (> 100 km(3)) extent, are distinguished on the basis of stratigraphic position, chemical and modal composition, 40Ar/39Ar age, and paleomagnetic direction. The most voluminous ash flows spread as far as 150 km from the caldera complex across a high plateau of limited relief-the Great Basin altiplano, which was created by late Paleozoic through Mesozoic orogenic deformation and crustal thickening. The resulting ignimbrite field covers a present area of similar to 60,000 km(2) in east-central Nevada and southwestern Utah. Before post-volcanic extension, ignimbrites had an estimated aggregate volume of similar to 33,000 km(3). At least seven of the largest cooling units were produced by super-eruptions of more than 1000 km(3). The largest, at 5900 km(3), originally covered an area of 32,000 km(2) to outflow depths of hundreds of meters. Outflow ignimbrite sequences comprise as many as several cooling units from different sources with an aggregate thickness locally reaching a kilometer; sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances, thus manifesting a lack of synvolcanic crustal extension. Fallout ash in the mid-continent is associated with two of the super-eruptions.