COLLABORATIVE RESEARCH: Geologic and GPS Study: DisplacementPartitioning and Arc-Parallel Extension in the Aleutian Volcanic Island Arc

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9714887 Oldow In circumstances where the convergence vector between two plates is oblique to the suture, deformation is partitioned into arc-parallel (strike-slip) and arc normal (thrust) components. The parameters controlling this partitioning are not well known, and several models exist. This research in the Aleutian arc takes advantage of a curved suture between plate where the vector varies smoothly from near O (orthogonal) to near 90o (pure strike-slip) to address some of the possible parameters. If the coupling between upper and lower plates remains constant, increasing arc-parallel extension in the upper plate with increasing obliquity should be observed. However, no arc-parallel extension need occur if coupling decreases with increasing obliquity. This project will employ GPS technology to determine translations of the islands along the Aleutian arc and structural analysis to determine operative slip and deformation response. Results should document partitioning of strain with increasing obliquity, identify operative slip mechanisms and allow testing of several hypotheses about partitioning in situation where convergent vectors are oblique to plate margins.