Late Pleistocene rhyolitic explosive volcanism at Los Azufres Volcanic Field, central Mexico Article uri icon

abstract

  • Los Azufres Volcanic Field hosts the second most important geothermal field of Mexico, with a production of 188 MW of electricity. Based on fieldwork and new geochronological data ( 14 C and 40 Ar/ 39 Ar) we define that activity at Los Azufres Volcanic Field started some 1.5 Ma with the emission of basaltic to rhyolitic lavas, and pyroclastic material. The late Pleistocene explosive activity in the southwest sector (Guangoche volcano area) of Los Azufres occurred in a narrow period of time between >31 and <26 ka. The pyroclastic stratigraphy of the S, SW, and W sectors is represented by diverse deposits of dacitic and rhyolitic composition, including a debris avalanche deposit related to a sector collapse of San Andrés volcano, several pyroclastic sequences associated with plateau forming lavas, and Guangoche volcano. Guangoche volcano was the focus of late Pleistocene eruptive activity with two Plinian and one subplinian events that deposited pumice-rich falls and pyroclastic flows and surges. These deposits are informally named the White Pumice (29 ka), which originated from a 23-km-high eruptive column and the ejection of 1.7 km 3 of tephra that covered an area of at least 223 km 2 with a mass discharge rate of 9 × 10 7 kg/s; the Ochre Pumice fall (<26 ka), deposited from a 16-km-high eruptive column involving 1.3 km 3 of tephra at a mass discharge rate of 1.9 × 10 7 kg/s; and the Multilayered fallout (≪26 ka) that resulted from an 11-km-high eruptive column with 1 km 3 of tephra at a mass discharge rate of 4.6 × 10 6 kg/s. The complete late Pleistocene stratigraphy suggests that explosive events at Los Azufres Volcanic Field have been intense. They are the subject of ongoing investigations to better understand this kind of large magnitude eruptions. © 2012 The Geological Society of America. All rights reserved.

publication date

  • 2012-01-01