Response of the technically erosive south Peruvian forearc to subduction of the Nazca Ridge: Analysis of three-dimensional analogue experiments

摘要

The collision zone of the obliquely subducting Nazca Ridge and the erosive Peruvian forearc is characterized by enhanced tectonic erosion, normal faulting, forearc uplift, and a minor indentation. We apply two three-dimensional sandbox experiments monitored by an optical particle imaging velocimetry system to decipher the spatial and temporal evolution of forearc deformation. During oblique convergence the rigid model ridge causes a wave of uplift followed by subsidence to shift along the forearc. By varying the strength of the analogue material we demonstrate that the forearc response to ridge subduction, in particular the amount and rate of uplift and wedge indentation, is controlled by the mechanical strength of the forearc. The model using the high-strength material yields results more compatible with the geological record of the Peruvian forearc.