The Maya-Chortís Boundary: A Tectonostratigraphic Approach

Abstract

This work presents an updated revision of the complex stratigraphic and tectonic relationships that characterize the geologic boundary between the Chortís and Maya continental blocks of the Caribbean region. Based on field, petrologic, structural and geochronological work in key areas of central Guatemala, as well as analysis of the relevant literature, we propose a new tectonostratigraphic structure that more fully appraises the fundamental tectonic role played by major faults that cut across the continental isthmus between the Americas, and bound separate tectonostratigraphic terranes (or fault blocks according to author JDK). Accordingly, we subdivide the area into seven of these units, from south to north: Chortís, Yoro, Sula, El Tambor, Jacalteco, Achí, and Maya, bounded respectively by the Agúan-La Ceiba, Jocotán-Chamelecón, Motagua, Baja Verapaz (defined in this work), and Chixoy-Polochic fault zones. Unfortunately, the extreme paucity of modern geologic data bearing on the pre-Cretaceous cover and basement units in the entire region constitutes a major obstacle for building convincing paleogeographic models to explain the complex tectonic evolution of the area from Precambrian to Cenozoic time. Consequently, this work should be taken as an attempt line to understand more clearly the nature and contact relationships between deep crustal blocks in nuclear Central America, and as a contribution to interpret their geologic evolution in plate tectonic terms.