4:00 PM - 4:15 PM
[SCG71-03] Plate Boundary Reorganization of the Pacific Plate during Cretaceous
Keywords:abyssal hill fabric, fracture zone, Hokkaido Trough, Pacific Plate, Cretaceous
The Hokkaido Trough is situated between Kuril Trench and Shatsky Rise. Most of the seafloor around the Hokkaido Trough were formed during the Cretaceous Normal Polarity Superchron (125.93-83.64 Ma), implying little magnetic anomaly lineations are available to reconstruct plate boundaries. Seafloor spreading fabric as abyssal hills and topographic features can give us the information of the reorganization of the mid-Cretaceous Pacific plate. We examined the topographic features around the Hokkaido Trough using multibeam bathymetric data. Most of the multibeam bathymetric data were obtained by the research cruises by R/V Mirai, JAMSTEC. The multibeam bathymetric data exposed the detailed topographic expression of the trough and seafloor spreading fabric around the trough. The topographic expression indicates that the Hokkaido Trough is not an abandoned spreading ridge proposed by Norton (2007). We found several curved troughs, which topographic feature is similar to those around the propagating ridges. Our study suggests that the reorganization of the Pacific-Izanagi ridge during Cretaceous was accompanied by propagation of the Pacific-Izanagi ridge and fragmentation of the Pacific plate.