| The geomorphology, geology, and Quaternary stratigraphy of the seismically locked 'Guerrera Gap' may reflect the long-term tectonic history of a unique portion of the Mexican subduction zone.; Results indicate that uplift has been occurring at La Saladita for sometime, and a series of 3 marine terraces of paleo-shorelines are present. In contrast, the lagoon El Plan shows evidence of long-term interseismic subsidence, possibly stretching back into the Holocene. The drainage basin of El Plan is tilted to the southeast. The lagoon Mitla shows evidence of high interseismic subsidence rates, with the most extensive drainage basin in the Guerrero Gap, with a tilt perpendicular to the coastline. Coyuca Lagoon has many characteristics of long term interseismic subsidence, perhaps the best indicators being a series of man made shell mounds and sand bars that are now submerged within the lagoon. Coyuca Lagoon has a tilt to the west away from Acapulco. The lagoon Tres Palos, in the Acapulco Gap, shows a high tilt and drainage to the southeast. It has heavy alluvial sedimentation, which can be clearly seen in its sediment core stratigraphy. It too shows interseismic subsidence over long time scales. (Abstract shortened by UMI.)... |
