Southwestward volcanic migration in the western Trans-Mexican Volcanic Belt during the last 2 Ma

Abstract

K-Ar dating and paleomagnetic results for the Chapala region provide age estimates for Miocene to Pleistocene volcanic rocks. For the Michoacan-Guanajuato Volcanic Field (MGVF), magnetostratigraphic studies led to an improved understanding of time and spatial patterns of volcanism. Trends of volcanism in the MGVF suggest a 90 km trenchward migration of volcanic activity around the Brunhes-Matuyama boundary (0.78 Ma). In the Chapala region a transitional and smaller spatial migration occurred around the Pliocene-Pleistocene boundary. This migration implied a change in magnetic evolution as shown by a decrease in size of volcanic edifices. -from Authors