1:45 PM - 2:00 PM
[SCG61-01] The enigmatic tectonics of the Jurassic Pacific plate
Keywords:Pacific Plate, magnetic anomaly lineations, bathymetry
The Hydrographic and Oceanographic Department of the Japan Coast Guard conducted the dense bathymetric and geomagnetic survey around the Marcus Island for the Extended Continental Shelf Survey (e.g., Fujisawa, 2009). We compiled the data to reveal seafloor spreading fabric and to identify magnetic anomaly lineations. Additional data were obtained from the databases of National Oceanic and Atmospheric Administration/National Centers for Environmental Information (NOAA/NCEI) and Japan Agency for Marine-Earth Science and Technology (JAMSTEC). We also used unpublished data obtained by Ocean Research Institute, the University of Tokyo (ORI, UT). The study of the geomagnetic data is presented by Kakurai et al. (this session). In this presentation, we show the tectonic history of the Jurassic Pacific plate using our bathymetric and magnetic studies.
We found several curved abyssal hills and magnetic bights. The strikes of curved abyssal hills are consistent with those of magnetic anomaly lineations, implying the curved abyssal hills represents the configuration of the Pacific-Izanagi-Farallon triple junction. Our study concluded that the configuration of the Pacific-Izanagi-Farallon triple junction before the M29 was a ridge-ridge-ridge. Our study also revealed the discontinuous of the trajectory of the Pacific-Izanagi-Farallon triple, although previous studies assumed the continuity of the trajectory to build the tectonic history of the Pacific plate.