Surface exposure ages of middle-late Pleistocene marine and fluvial terraces along the northern and southern Sanriku coasts, Northeast Japan

Wakasa, Sachi*; Ishiyama, Tatsuya*; Hirouchi, Daisuke*; Matta, Nobuhisa*; Fujita, Natsuko   ; Echigo, Tomoo*

To estimate long-term rates of coastal uplift along the northern Pacific coast of Northeast Japan, we determined the surface exposure ages of marine and fluvial terraces based on terrestrial in situ cosmogenic radionuclide dating of exposed bedrock surfaces. Based on reinterpretation of marine and fluvial terraces, we collected samples from the northern and southern Sanriku coast. The surface exposure ages from Be concentrations in quartz calculated from the measured Be/Be ratios commonly suggest middle to late Pleistocene ages for the marine and fluvial terraces and slow coastal uplift rates at intermediate timescales. The results demonstrate different styles of crustal strain accommodation in the northern Northeast Japan arc above the subducting Pacific plate.