Basement, Curie isotherm and shallow-crustal structure of the Trans-Mexican Volcanic Belt, from aeromagnetic data

Abstract

Regional aeromagnetic data from the western part of the Trans-Mexican Volcanic Belt (TMVB) have been analyzed using the spectral method to estimate depths to the magnetic basement and shallower magnetic interfaces. The basal calc-alkaline volcanic products (Miocene-Early Pliocene) of the TMVB become thinner from west to east, whereas the Plio-Quaternary volcanism becomes thinner from east to west. The underlying sedimentary Mesozoic sequence is thicker in the east. A crystalline basement proper is observed from the Guadalajara City area to the east. To the west of Guadalajara, the basement is represented by a granitic substratum which is extensively exposed in the Jalisco block. Preliminary estimates indicate that the Curie point isotherm ranges from 7 to 14 km, which is in agreement with heat flow studies in the area. The crustal structure inferred from the aeromagnetic data and regional geology, is constructed for ten sections which correspond to the geophysical profiles.