The Impact of the Caroline Ridge Subduction on the Geomorphological Characteristics of Major Landforms in the Yap Subduction Zone

Abstract

The Caroline Ridge (CR) subduction underneath the Philippine Sea Plate brings complex morphotectonic characteristics to the Yap Subduction Zone (YSZ) compared to other normal intra-oceanic subduction systems. However, due to the relative paucity of precise geomorphological information, the detailed morphotectonic settings of the YSZ remain unclear. Therefore, we combine the latest-released bathymetry, marine geomorphometry techniques, and geophysical information to investigate the geomorphological characteristics of landforms in the YSZ and their inter-relationship with the CR subduction. The Parece Vela Basin displays NE-SW oriented fractures which are believed to be influenced by the subduction of CR in the ESE-WNW direction. The north part of the Yap arc exhibits higher Bouguer anomalies, implying the absence of the overlying normal volcanic arc crust. The arc-ward trench shows abnormal higher slope values and reveals two significant slope breaks. The Yap Trench axis reveals varying water depths with an extraordinarily deep point at around 9000 m. The sea-ward trench slope displays higher slope values than normal and shows the presence of grabens, horsts, and normal faults which indicate the bending of the CR before subduction. The CR subduction is observed to be critical in the formation of significant geomorphological characteristics in the YSZ.