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- Title
Improved High‐Resolution Bathymetry Map of Tamu Massif and Southern Shatsky Rise and Its Geologic Implications.
- Authors
Thoram, S.; Sager, W. W.; Reed, W.; Nakanishi, M.; Zhang, J.
- Abstract
The formation and geology of oceanic plateaus are incompletely understood, in part because geophysical data are sparse and of low density. This paper presents an improved high‐resolution bathymetry map for southern Shatsky Rise, by combining newly acquired multibeam bathymetry data from several cruises and by filling in gaps in multibeam coverage with the SRTM15+ global bathymetry model. This map provides important insights on the evolution of Shatsky Rise from plateau forming, to post‐plateau secondary volcanism, to sedimentation, erosion, and sedimentary mass wasting. Tamu Massif is segmented by several subdued bathymetric troughs that divide the massif flanks into smaller rises. The segmentation pattern suggests Tamu Massif was built by a series of eruptions along a jumping triple junction. The distribution of secondary volcanic cones is non‐uniform, with most occurring on the southern and eastern flanks. Most of these secondary cones occur as short chains that parallel nearby magnetic lineations, suggesting control by spreading ridge parallel faults. These results suggest the evolution of Shatsky Rise was largely controlled by spreading ridges during its active volcanic phase. Numerous escarpments were identified around the plateau, a majority of which parallel bathymetry contours, suggesting these features developed because of differential subsidence of the rise massifs. The map reveals widespread mass wasting and downslope sediment movement, shifting sediment distribution and changing the surface morphology. Improved topography improves our understanding of the evolution of Shatsky Rise and emphasizes the importance of bathymetry data in deciphering the geodynamic evolution of large igneous provinces. Plain Language Summary: Shatsky Rise is a large oceanic plateau located in northwest Pacific Ocean offshore Japan. It formed from hotspot volcanism that erupted along a moving triple junction, forming volcanic mountains along the way, of which Tamu Massif and Ori Massif are the largest. We present new high‐resolution bathymetry map of southern Shatsky Rise by merging newly available multibeam data with existing data and filling gaps in coverage with ba/thymetry estimated from satellite altimetry. Studies considered Tamu Massif as a large edifice formed from voluminous ridge‐centered eruptions. However, the map reveals Tamu Massif to be segmented by several shallow valleys that divide it into five smaller mountains, each forming at a jumping triple junction, suggesting that Tamu Massif was built by a series of ridge‐centered eruptions. The map also shows non‐uniform distribution of secondary volcanic cones over Tamu Massif, majority of them located over eastern and southeastern flanks due to preferential volcanism occurring near the Pacific‐Farallon ridge. When a volcano becomes dormant, it becomes covered with sediments, a process often thought to be simple accumulation. We discovered evidence of substantial sedimentary movement that has occurred and is likely still occurring, suggesting that volcano morphology can significantly vary long after it becomes volcanically inactive. Key Points: We present a high‐resolution bathymetry map of southern Shatsky Rise with greater multibeam coverage revealing small‐scale surface featuresTamu Massif is subtly segmented into 5 smaller rises consistent with formation by series of ridge eruptions along a jumping triple junctionSecondary volcanic cones are distributed mainly over the southern and eastern flanks, and many have trends implying spreading ridge control
- Subjects
JAPAN; OCEANIC plateaus; BATHYMETRY; MULTIBEAM mapping; IGNEOUS provinces; VOLCANISM; SURFACE morphology; GEOLOGY
- Publication
Journal of Geophysical Research. Solid Earth, 2022, Vol 127, Issue 11, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2022JB024304