The Aztlán Fault System: Seismic and gravity characterization 315 Boletín de la Sociedad Geológica Mexicana Volumen 67, núm. 2, 2015, p. 315-335 D GEOL DA Ó E G I I C C O A S 1904 M 2004 . C EX . ICANA A C i e n A ñ o s The Aztlán Fault System: control on the emplacement of the Chichinautzin Range volcanism, southern Mexico Basin, Mexico. Seismic and gravity characterization José Oscar Campos-Enríquez1,*, Javier Francisco Lermo-Samaniego2, Yanet Teresa Antayhua-Vera3, Marcos Chavacán3, Victor-Manuel Ramón-Márquez3,4 1 Instituto de Geofísica, Universidad Nacional Autónoma de México, México, D.F., México. 2 Instituto de Ingeniería, Universidad Nacional Autónoma de México, México, D.F., México. 3 Programa de Posgrado de Ciencias de la Tierra, Universidad Nacional Autónoma de México, D.F., Mexico. 4 Facultad de Ingeniería, Benemérita Universidad Autónoma de Puebla, Puebla, México. *
[email protected] Abstract Gravity and seismic studies enabled us to establish the major features of the shallow crustal structure beneath Chichinautzin Range. Accordingly, the Chichinautzin Range evolved above Mesozoic calcareous rocks lying on a metamorphic basement. To the north and south this basement is downfaulted. Nevertheless the north dipping faults downward displace the basement to larger depths (2 to 3 km) in the Mexico and Toluca basins. In the Morelos Basin, the basin is shallower. As block-faulting evolved, the basement edge migrated southwards, thus widening an E-W oriented major depression south of the Mexico Basin. In particular, gravity modeling enabled us to integrate the different faults mapped up to today in and around the Chichinautzin Range into a fault system that can be correlated from the Nevado de Toluca.