Quaternary intra-arc extension in the central Trans-Mexican volcanic belt
Suter, Max; Martinez, Margarita Lopez; Legorreta, Odranoel Quintero; Martinez, Miguel Carrillo (2001) Quaternary intra-arc extension in the central Trans-Mexican volcanic belt. Geological Society of America Bulletin, vol.113, no.6, pp.693-703, Jun 2001
| Authors | Suter, Max; Martinez, Margarita Lopez; Legorreta, Odranoel Quintero; Martinez, Miguel Carrillo |
|---|---|
| Year | 2001 |
| Title | Quaternary intra-arc extension in the central Trans-Mexican volcanic belt |
| Source | Geological Society of America Bulletin, vol.113, no.6, pp.693-703, Jun 2001 |
| ISSN | 0016-7606 |
| GeoRef | 2001-043105 |
| Keywords | active faults; Cenozoic; deformation; displacements; earthquakes; East Pacific; extension; faults; grabens; half grabens; Mexico; Middle America Trench; neotectonics; North Pacific; Northeast Pacific; orientation; Pacific Ocean; Quaternary; seismic risk; seismicity; slip rates; subduction zones; systems; tectonics; Trans-Mexican volcanic belt; volcanism |
| Notes | Includes appendix |
| DOI | 10.1130/0016-7606(2001)113<0693:QIAEIT>2.0.CO;2 |
Abstract
The Trans-Mexican volcanic belt is an active volcanic arc related to subduction along the Middle America trench and characterized by shallow seismicity and synvolcanic to postvolcanic extensional arc-parallel faulting. Major intra-arc basins within the central part of the belt between long 99 degrees W and 102 degrees W are from west to east the Cuitzeo and Acambay grabens, the Aljibes half-graben, and the Mezquital graben. In this region, approximately 100 east-west-striking, >2 km long, steeply dipping normal faults, expressed by pronounced multi-event fault scarps, have been mapped. Of the 100 faults, approximately 65 displace rocks of known Quaternary age younger than 1.6 Ma, and 22 cut rocks with a documented age younger than 750 ka. Known historical surface ruptures are limited to faults of the Acambay graben. Overall, the faults cause north-south to north-northwest-south-southeast-oriented extension of <1 km, which is distributed over a 30-50-km-wide zone that has 5-10 faults in cross section and a relative extension of <3%. Quaternary vertical slip rates, estimated for 13 of the faults, have a mean of 0.07 mm /yr. They are highest at the southern margin of the Cuitzeo graben, the northern margin of the Acambay graben, and in the Aljibes half-graben, where they measure between 0.16 and 0.18 mm /yr. The north-south to north-northwest-south-southeast-oriented Quaternary bulk extension rate of the system is likely to be 0.2+ or -0.05 mm/yr. This fault system is in an initial stage of coalescence. Its western and eastern parts consist mostly of isolated fault segments, whereas in the central part deformation is localized onto a few through-going faults. The longest of these are the Venta de Bravo fault 45 km and the Acambay-Tixmadeje fault 34 km. The short fault traces have a simple structure, whereas the longer ones are commonly composed of two or more segments. There is no obvious migratory pattern of Quaternary fault activity, which suggests that the entire region is tectonically active.