2-D Numerical modelling Experements on slab breakoff mechanism beneath the Java Trench

We conducted a series of numerical modelling experiments to investigate the mechanism of slab breakoff beneath the Java Trench. The subduction of seamounts, which are characterized by overthickened and buoyant crust, can be a key factor conducive to slab detachment. The modeling experiments explored a range of variable parameters, including whether seamount is involved in the subduction process, the geometry and rheological properties of the seamount, the convergence rate, and the age of subducting oceanic lithosphere. The modelling results demonstrate that the presence of seamount significantly affects the slab breakoff process. Slab breakoff typically occurs at the edges of the subducting seamount. The specific geometry and rheological strength of the seamount emerges as the internal factors in determining whether the slab breakoff will occur. Additionally, the slab age and convergence rate are the external effective controlling factors on the timing and depth of slab breakoff. The evolution of surface elevation caused by seamount subduction differs from that of general oceanic lithosphere subduction, featuring an additional uplift event related to the slab breakoff. Based on our findings, we infer that the participation of seamounts in the subduction process beneath the Java Trench (110°E) has led to the development of low-velocity zone in the mantle wedge and high potassium volcanoes in the Java Island, which has further resulted in a compressional tectonic region in the overriding continental crust.