Deformation history of the Maya and Chortis blocks: Insight to the evolution of the Motagua fault zone, Guatemala

Abstract

Structural analysis of units astride the Motagua fault zone, the boundary between the North American and Caribbean plates in Guatemala, is critical to understanding the tectonic evolution of the northwestern Caribbean region. Existing models consider minimal geochronological data and are based on little structural data. Furthermore, published studies of the region predate concepts of microstructures and kinematic indicators. This study integrates classical structural analysis, contemporary techniques, and geochronological data to constrain a tectonic model for the Maya and Chords blocks. Four ductile phases in the Maya block and five in the Chortis block signal two separate tectonic collisions, as progression of structures and strain fields of Maya and Chortis is not correlative. Evidence is presented for collision of Chords and southwestern Mexico at ∼120Ma and for Maya and the Nicaraguan Rise at ∼70Ma. Four brittle phases in both blocks reflect recent deformation following translation of Chords to its current position