RELATIONSHIP BETWEEN SUBDUCTION ZONE DYNAMICS AND THE GEOMORPHOLOGY OF THE RESULTING OROGEN

The relationship between the angle of the subducting plate and the dynamics of the subduction zone (e.g. resultant magmatism, earthquakes, and deformation) has been well characterized. This study uses GIS to display the subducting plate age and motion, location of earthquakes and volcanoes, and uplift patterns for multiple subduction zone boundaries. Measurements were made along the subducting plates direction of motion for each boundary. These measurements include: the distance from trench to axis of volcanism; the width of uplifted area; the offset of uplifted area from trench; and the offset of maximum elevations from trench. These measurements were compared to the plate convergence rate; age of subducted lithosphere; and angle of subduction determined from the Wadati-Benioff Zone. The preliminary study focused on the Andean Subduction zone. There were a couple notable patterns that were observed. First, the subduction zones with older lithosphere at the trench tended to have steeper angles of subduction. The general relationship between the age of the subducting slab and angle of subduction is not a new, however, this project’s goal is to illustrate the relationship between subduction angle and morphology of the overlying orogen. Therefore, the second observation: the steeper angles of subduction lead to the formation of an orogen that is closer to the trench, was somewhat wider, and had a higher maximum elevation. This suggests that there is a dynamic coupling between the evolving orogen and the subduction zone dynamics.