The NE-SW Axaxalpa fault system in the eastern sector of the Transmexican Volcanic Belt: Kinematics, geometry, and recent activity

The Axaxalpa fault system (AFS), located in the eastern sector of the Transmexican Volcanic Belt (TMVB), consists of NE-SW oriented faults that record two deformation events. The oldest event (D1) corresponds to faults with left strike-slip kinematics, which were active during the late Miocene. These faults cutiddle-late Miocene volcanic structures in the northern zone of the eastern sector of the TMVB and are likely associated with intrusive bodies along their trace. The second event (D2) is related to the normal movement of the NE-SW faults. This activity started in the Pliocene and continued into the Holocene. The fault-slip data inversion of the faults located in the southern zone of the AFS for the D2 suggests that the main stress directions are 131°/59° (trend/dip), 223°/01°, and 314°/31° for σ₁, σ₂, and σ₃ respectively, and stress ratio R = (σ2- σ3)/(σ1- σ3) = 0.44. In the northern sector, the main stress directions are 292°/76°, 047°/06°, 138°/12° for σ₁, σ₂, and σ₃ respectively, and stress ratio R = 0.45. The mesoscopic fractures associated with D2 are mainly extensional and hybrid and have three orientations: NE-SW, NNW-SSW, and ∼E-W. Additionally, the morphological lineaments primarily show a NE-SW orientation, with subordinate NW-SE and ∼E-W orientations. The D2 event controls the volcanic vent's location and forms monogenetic volcanic lineaments parallel to the NE-SW faults.

Based on the AFS orientation, it is clear that this fault system is incompatible with the field stress recorded in the TMVB. This fact suggests that the AFS is probably related to a reactivated basement structure inside of a tridimensional deformation with a complex deformation history. In the southern zone of the eastern sector of the TMVB, the Cretaceous Papalutla fault probably represents the continuation of the AFS.