Effects of Seamount Subduction on Tectonic Accretion, and Erosion, and Forearc Evolution: Discrete Element Simulations

[摘要] A series of deep imbricate thrust structures associated with a period of margin accretion, have been interpretedinseismicreflectiondataoffshoreCostaRica.Thisinterpretationforaccretionis inconsistent with the long-term margin subsidence recordedin that setting. Using Discrete Element Method simulations, we test the idea that thinning of the incoming sedimentary blanket exposed underlying seamounts that interacted with the overriding plate, and drove a change in tectonic regime from margin accretion to erosion.Our modeling results show seamountscan enhance the rates of wedge growth, at least transiently, even as they cause erosion during later stages of forearc evolution.Seamountsalsoimpartconsiderablechangestoforearcstructureastheypassby, rotatingfaults,initiatingacross-cuttingbackthrusts,activatinglandslides,andsteepeningthe forearcslopes.Wealsoshowseamountspartitioningstrainwithinthewedgebylandward reactivation of structures, which may have implications to seismogenesis.

[发布机构] Rice University

[效力级别] Subduction