Southern Mexico is a very interesting area where the subducting Cocos slab drastically changes its geometry: from a flat slab in Central Mexico to a ~ 45° dip angle beneath Chiapas. Also, the currently active volcanic arc, the modern Chiapanecan volcanic arc, is oblique and situated far inland from the Middle America trench, where the slab depth is ~ 200 km.
Continue reading “Chiapas, Mexico. Internal Structure. Mantle.”
Extensive diversity and complexity of tectonic regimes characterizes the perimeter of the Caribbean plate, involving no fewer than four major plates (North America plate, South America plate, Nazca plate, and Cocos plate). Inclined zones of deep earthquakes (Wadati-Benioff zones), ocean trenches, and arcs of volcanoes clearly indicate subduction of oceanic lithosphere along the Central American and Atlantic Ocean margins of the Caribbean plate. While crustal seismicity in Guatemala, northern Venezuela, and the Cayman Ridge and Cayman Trench indicate transform fault and pull-apart basin tectonics.
Continue reading “Central America Tectonic Setting”