Subduction erosion along the Mariana margin

Abstract:

Due to the complexity of the plate tectonic background, different types of convergent plate boundaries have been formed. Convergent plate margins controlled by subduction erosion are currently the most common type of plate boundary. The Mariana margin is considered to be a typical erosive convergent plate margin, and the main material transfer mode is controlled by subduction erosion. However, the subduction processes on such conditions remain poorly investigated and understood.

In our research, we use a novel data fusion method to fuse the measured multi-source bathymetric data with the GEBCO_2020 bathymetric data set to obtain the high-precision bathymetric data with a resolution of 100m in the Mariana area. In addition, we combined with the collected multi-channel seismic profile data to study the subduction mechanism of the Mariana margin from the perspective of tectonic geomorphology, and the subduction erosion mode along the Mariana margin was established.

The Mariana margin is an interaction area between oceanic plates. Due to the lack of continental sediments, it is prone to subduction erosion. We found that a lot of horst and graben structure or seamounts and other high bathymetric relief are widely developed on the subducting Pacific seafloor, with a convergence rate of 8.4cm/a, the "V"-shaped trench cross section and the underdeveloped accretionary wedges, promoting the subduction erosion process on the Mariana margin. The subduction erosion process from north to south on the Mariana margin is complex. With the subduction of the Pacific plate, the graben structure is usually filled with loose sediments, making the subduction surface relatively smooth and slowly rubbing against the base of the overlying plate. What's more, if there is no sediment interface to reduce the friction between the plates, the subducting oceanic crust and the overlying oceanic crust usually have a strong coupling effect, which strongly erodes the bottom of the overlying plate. The understanding about the different types of subduction erosion processes along the Mariana margin is of great significance for the study of the subduction process and inter-plate interaction of global intra-oceanic margins.