New Understanding of the Southeastern Caribbean Plate Boundary
Gary Pavlis and graduate students from IU's Department of Geological Sciences have been involved in the BOLIVAR (Broadband Ocean-Land Investigation of Venezuela and the Antilles Arc Region) study of the southeastern Caribbean plate boundary since 2003. This project is part of a large collaborative program with Rice University, the University of Texas at Austin, the Scripps Institution of Oceanography, and others. Indiana's primary role in this project was the deployment of a large, passive array experiment to image the upper mantle along the northern boundary of South America that marks the plate boundary between South America, the Caribbean, and the Atlantic. This experiment was the first successful deployment of a new generation of broadband ocean bottom seismometers.
This area that was studied is a tectonic "corner" defined by the southern termination of the Antilles subduction zone. The three-dimensional geometry of this corner has been a subject of controversy for decades. The prevailing model was an expected partial subduction of the Caribbean plate beneath the South America plate. This study revealed a surprising result seen in the diagram below.
We see a remnant of the Atlantic sitting at the base of the transition zone. This result indicates that the dominate process that has operated on the southeast Caribbean plate margin for the past 20 million years is vertical shearing of the Atlantic Plate and a linked trench rollback that has led to the previously well documented eastward propagation of the trench over this time period.
Students in the Department of Geological Sciences are involved in field work collecting data and also in its analysis. With a student/faculty ratio under 3/1 it can be far easier to become involved in research projects and field work than at many other institutions.