[S-CG52] Ocean Floor Geoscience

[SCG52-08] Revising magnetic anomaly lineations in the northwestern Pacific Ocean using the latest data

*Juri Uda ¹, Masao Nakanishi², William W Sager³ (1.Department of Earth Sciences, Faculty of Science, Chiba University, 2.Department of Earth Sciences, Graduate School of Science, Chiba University, 3.Earth and Atmospheric Sciences Department, University of Houston)

Keywords:magnetic anomaly lineation, northwestern Pacific Ocean

We revised Late Jurassic and Early Cretaceous magnetic anomaly lineations in the northwestern Pacific Ocean using the latest geomagnetic data. Five sets of magnetic anomaly lineation exist in the northwestern Pacific Ocean. They are Japan, Hawaii, Mid-Pacific Mountains, Magellan, and Phoenix lineation sets (Nakanishi et al., 1992). Nakanishi and (1998) revised magnetic anomaly lineations in the Central Pacific Basin. Nakanishi et al. (1999; 2015) revised magnetic anomaly lineations around Shatsky Rise. Nakanishi (2011) revised magnetic anomaly lineations around the Japan Trench. There are still places where magnetic anomaly lineations have been reexamined, although geomagnetic data increased after Nakanishi et al. (1992).
The data used in this study are composed of total geomagnetic field data by a surface-towed magnetometer and vector geomagnetic data by a shipboard vector magnetometer. The geomagnetic data are obtained from the databases of several domestic and overseas organizations (e.g., Japan Agency for Marine-Earth Science and Technology and National Oceanic and Atmospheric Administration/National Geophysical Data Center). We calculated magnetic anomaly using CM4 (Comprehensive Model 4: Sabaka et al. 2004) and IGRF (International Geomagnetic Reference Field: IGRF13th: Alken et al., 2021). In addition to identification of magnetic anomaly lineations, we reexamined the several major fracture zones using multibeam bathymetric data (Nakanishi et al. in this session).
We revised magnetic anomaly lineations in several places; north and southeast of the Shatsky Rise, around the Japan Trench, and north of Mid-Pacific Mountains.