An Integrated Study of the Chuacus Metamorphic Belt (Guatemala): A UHP Terrane Along the North America-Caribbean Plate Boundary?

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This project that is jointly supported by the Division of Earth Sciences and the Office of International Science and Engineering, is designed to study a recently discovered Chuacus terrane in Guatemala. This terrane was developed in a subduction - collision of continental microplate environment, and opens an excellent opportunity to address this problem at the southern margin of the North-American plate in the Caribbean region. The formation and exhumation of deeply subducted rocks to mantle depths has been one of the most exciting problems in the field of continental dynamics for the last two decades. This project undertakes an integrated petrochemical-geochronological study, and the specific tasks involve field study along orogen-perpendicular traverses, petrochemical characterization of eclogitic and gneissic rocks to constrain thermobaric structures, and dating of subduction, collision and exhumation of continental materials by U-Pb SHRIMP and 40Ar-39Ar methods. The proposed research provides basic information concerning the age, protolith, HP-UHP metamorphism and tectonic evolution of a continental-affiliated terrane. This gneissic terrane, with mafic eclogitic layers, contrasts with the oceanic-affiliated HP terranes to the south of Motagua Valley. The subparallel occurrence of continental-derived and oceanic-derived eclogitic terranes in central Guatemala is unique, and provides a challenge for geosciences for their formation and juxtaposition. Spatial and temporal relations of oceanic subduction followed by subudction and collision of continent may have been involved in the early development of the Caribbean plate. This project supports research of a Ph.D. student from Colombia, a Japanese post-doc, Stanford faculty members and undergraduates and personnel from both Guatemala and Mexico. An essential part of this collaborative research with local scientists will involve training young Mexican and Guatemalan scholars in scientific writing and in research methods and techniques to which they lack access at the present time. Such tri-national cooperative project will enhance mutual friendship, exchanges, and both scientific cooperation and educational training.