Potrillo volcanic field

Potrillo volcanic field
Potrillo volcanic field viewed from the south, just west of Kilbourne hole, after light snow from winter storm Goliath
Highest point
Elevation	5,561 ft (1,695 m)
Prominence	657 ft (200 m)
Coordinates	31°54′N 107°12′W / 31.900°N 107.200°W / 31.900; -107.200Coordinates: 31°54′N 107°12′W / 31.900°N 107.200°W / 31.900; -107.200
Geography
Location	New Mexico, United States / Chihuahua, Mexico
Geology
Age of rock	< 2.65 million year
Mountain type	Volcanic field
Volcanic arc/belt	Rio Grande rift
Last eruption	> 150,000 years ago

The Potrillo volcanic field is a monogenetic volcanic field located on the Rio Grande Rift, in a portion of its rift valley, in southern New Mexico, United States and northern Chihuahua, Mexico. The volcanic field lies 22 miles (35 km) southwest of Las Cruces, New Mexico.

The Rio Grande rift is a north–south rift valley in the Basin and Range Province of western North America.

The Rio Grande rift is a tectonically active structure that has evolved during two stages:

What is thought is that molten rock went into crustal cracks which sometimes exploded violently onto the earth’s surface up and down the rift. Several thousand years ago, here in the Potrillo volcanic field, white-hot magma rose from 50 miles (80 km) under the surface up through structural fractures toward the surface to change all the landscape appearance.

In some places molten rock intruded into depositional sand but it failed to erupt through the surface, so erosion took place to expose the igneous formations. In other places molten rock erupted explosively, producing clouds of solidified lava that later fell back to earth as ash, forming a cone around the vent. In some cases, it erupted several times as a succession of lava flows from a single vent forming widespread basalt layers taking on the form of a shield. At times, molten rock came into contact with water-saturated sand and it produced superheated and highly pressurized water vapor that exploded though the earth’s surface with a devastating force creating large craters known as maars or lakes.

In the Potrillo volcanic field, there are 10 to 15 foot thick layers of basalt spread across the volcanic field, from lava breaching the walls of the cinder cone and shield volcanoes, spilling down the flanks and spreading across the surrounding surface. The Potrillo area is generally classified as part of the southern Rio Grande rift and shows the Cenozoic tectonic evolution of that structure. Extension took place in an intense 30–20 Ma phase, involving low-angle normal faults, and a less intense <10 Ma phase, involving high-angle normal. Mack & Seager (1995) argued that the Quaternary magmatism reached the surface via a transfer zone linking two adjacent N–S-trending, long-lived, extensional structures—the West Robledo and Camel Mountain faults.