[SIT24-P04] Sedimentary structure and tectonic setting of the Lyra basin central-western Pacific Ocean
Keywords:Ontong Java Plateau, multi-channel seismic reflection survey, Large Igneous Provinces
The Lyra basin is located on the western side of the OJP. The depth of the seafloor in the Lyra basin get deeper toward the west, from 4000 to 5000 m. There is an NW-SE trending graben named Lyra Trough crossing the Lyra basin. The survey lines of Lyra basins were two lines. One is parallel to the Lyra trough, and another is perpendicular to the trough.
We found several tectonic and intrusion structures in the Lyra basin. The relief of the acoustic basements in the basins are rough. This rough relief is caused by intrusions and extrusions. These intrusions and extrusions support recent volcanism in Lyra basin (Shimizu et al., 2015). We identified many normal faults with displacements about 10-20 m. Some of these faults reach seafloor. There are normal faults with displacements about 600 m in survey line of perpendicular to the Lyra trough. These large faults formed step-like acoustic basement. Theses faults are covered with sedimentary layer which not deformed. This may be related to the formation of Lyra trough.