GEOLOGIC EVALUATION OF PLATE KINEMATIC MODELS FOR THE NORTH-AMERICAN CARIBBEAN PLATE BOUNDARY ZONE

Four published plate kinematic models for the present-day North American-Caribbean plate boundary predict significantly different fault behavior along this dominantly strike-slip plate boundary zone (PBZ). Using a computer graphics system, we compare the deformational pattern predicted by the four kinematic models with geologic and seismic observations along the entire length of the PBZ from Central America to the northern Lesser Antilles. Our results indicate that none of the kinematic models predict all the geologic and seismic observations across the entire PBZ. However, all four models predict mapped fault character and observed earthquake focal mechanisms along certain segments of the PBZ. We conclude that the present-day deformation within the North American-Caribbean plate boundary zone cannot be described by rotation about a single pole. Instead, the Caribbean "plate" appears to be segmented into at least three major "sub-plates" or blocks, each of which requires an individual pole of rotation to describe its motion relative to the North American plate. Sub-plate boundaries correspond to two poorly studies zones of diffuse deformation within the Caribbean plate (Honduras Depression of Central America and Beata Ridge of the Caribbean Sea).