Oblique convergence and back-arc extension in northern Taiwan-Ryukyu area: Insights from sandbox modeling

Taiwan is located on the convergent boundary between the Eurasian Plate and the Philippine Sea Plate. The specific process of the Taiwan orogeny is a hot issue for many years. Sandbox modeling is a way to simulate the mountain building processes. The previous studies of sandbox modeling in Taiwan are more concentrated on the effect of arc-continent collision and basement high but few noted the effect of opening of Okinawa Trough. Our 3D experiments aim at better understanding of the structure and tectonic evolution of northern Taiwan-Ryukyu area by adding a sandpaper machine which could move freely in experiment and composed by motor, bearing and sandpaper, to simulate the opening of the Okinawa Trough. Results from sandbox modeling indicate that the following phenomena may be due to the opening of Okinawa Trough: (1)counter motion relative to the Philippine Sea Plate and subsidence in the Ilan Plain , (2)clockwise rotation of the Ryukyu Arc, (3)a linear subsidence zone and a series of small-scale normal fault in the Okinawa area.