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 the Tizapan Group (Late Miocene-Early Pliocene), Chapala Group (Late Miocene-Early Pliocene), Travesaño Group (Early Pliocene), Grande Group, Palo Verde Group and Zacoalco Group (Late Pliocene-Early Pleistocene), Santa Cruz Group, and Acatlan Group(Early Pleistocene). For the Michoacan-Guanajuato Volcanic Field (MGVF), magnetostratigraphic studies led to. an improved understanding of time and spatial patterns of volcanis. 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 magmatic evolution as shown by a decrease in size of volcanic edifices.