The North America-Caribbean plate boundary west of the Motagua-Polochic fault system:: a fault jog in Southeastern Mexico

We propose a model for the western end of the North American-Caribbean plate boundary. We suggest that, beyond the surface trace of the Motagua-Polochic fault system, interplate strain is distributed along the Reverse Faults Tectonic Province, a zone of long, narrow anticlines cut along their flanks by reverse faults that generally eliminate the intervening synclines, and the strike-slip faults of southeastern Mexico, a system of at least nine major faults with left-lateral displacement and documented seismic activity. The reverse faults act as a stepover (fault jog) between the strike-slip faults and the Motagua-Polochic system. Comparison with available stress data and models of the stress field at a stepover agree well with the observed pattern of folding and faulting in the area. Proposed displacement and seismicity along each individual fault in the SE Mexico strike-slip system must be small because interplate strain is shared between at least seven major strike-slip faults. We suggest that motion between North America and the Caribbean dies out at the northwestern end of the strike-slip faults. (C) 2000 Elsevier Science Ltd. All rights reserved.