16:30 〜 16:45
[SCG55-11] Interaction between seafloor spreading and arc formation
キーワード：フィリピン海プレート、伊豆小笠原マリアナ弧、西フィリピン海盆、海底拡大軸
Subduction initiation between two plates and the subsequent birth and development of an arc-backarc system are fundamental processes in plate tectonics. The Izu-Bonin-Mariana arc system in the Western Pacific has been the subject of extensive study to understand subduction initiation.
The origin and history of spreading of the West Philippine Basin (WPB) and its tectonic relation to the adjacent Izu-Bonin-Mariana arc in the Philippine Sea Plate remains poorly-understood. Especially, understanding of the temporal and tectonic relationship between the birth of the Izu-Bonin arc and the West Philippine Basin is critical for reconstruction of Philippine Sea plate tectonics, which closely links to subduction initiation of the Pacific Plate along its margin.
The YK22-11S cruise aimed to investigate the origin and age of magmatism and structure of intersection between the spreading axis of the WPB (CBF Rift) and the Kyushu-Palau Ridge (KPR), i.e., remnant Izu-Bonin-Mariana arc. Targets included: 1) relationship between volcanic ridge with MORB character and KPR crust; 2) NNE-SSW trending fault scarp on the western margin of the KPR (possibly formed associated with spreading of the WPB; 3) crustal section of the CBF Rise; and 4) WPB ocean crust formed at the very end of spreading.
Five Shinkai 6500 submersible dives were conducted in the CBF Rift–KPR intersection area. Two dives were conducted in the area where the CBF Rift appears to intersect the KPR. These dives observed a E-W trending ridge and fault scarps, and recovered basaltic rocks. The third dive revealed stratigraphy of western margin of the KPR dissected by NNE-SSW fault. This observation could provide crucial information to understand the age and formation process of this escarpment, which is one of the major tectonic features in the CBF Rift–KPR intersection.
Two dives were conducted in the CBF Rift. One dive observed an ESE-WNW trending ridge, which might be one of the youngest volcanic features in the rift. This dive recovered samples of basaltic lava flows, quite often showing morphological characteristics of pillow lava. Another dive in the rift examined a section of the CBF Rise. This dive again recovered a number of basalt samples of pillow lava origin and also hyaloclastite.
This presentation will report age and geochemical characteristics of the recovered basalts and discuss possible volcanic and tectonic processes at an arc-spreading center intersection.
The origin and history of spreading of the West Philippine Basin (WPB) and its tectonic relation to the adjacent Izu-Bonin-Mariana arc in the Philippine Sea Plate remains poorly-understood. Especially, understanding of the temporal and tectonic relationship between the birth of the Izu-Bonin arc and the West Philippine Basin is critical for reconstruction of Philippine Sea plate tectonics, which closely links to subduction initiation of the Pacific Plate along its margin.
The YK22-11S cruise aimed to investigate the origin and age of magmatism and structure of intersection between the spreading axis of the WPB (CBF Rift) and the Kyushu-Palau Ridge (KPR), i.e., remnant Izu-Bonin-Mariana arc. Targets included: 1) relationship between volcanic ridge with MORB character and KPR crust; 2) NNE-SSW trending fault scarp on the western margin of the KPR (possibly formed associated with spreading of the WPB; 3) crustal section of the CBF Rise; and 4) WPB ocean crust formed at the very end of spreading.
Five Shinkai 6500 submersible dives were conducted in the CBF Rift–KPR intersection area. Two dives were conducted in the area where the CBF Rift appears to intersect the KPR. These dives observed a E-W trending ridge and fault scarps, and recovered basaltic rocks. The third dive revealed stratigraphy of western margin of the KPR dissected by NNE-SSW fault. This observation could provide crucial information to understand the age and formation process of this escarpment, which is one of the major tectonic features in the CBF Rift–KPR intersection.
Two dives were conducted in the CBF Rift. One dive observed an ESE-WNW trending ridge, which might be one of the youngest volcanic features in the rift. This dive recovered samples of basaltic lava flows, quite often showing morphological characteristics of pillow lava. Another dive in the rift examined a section of the CBF Rise. This dive again recovered a number of basalt samples of pillow lava origin and also hyaloclastite.
This presentation will report age and geochemical characteristics of the recovered basalts and discuss possible volcanic and tectonic processes at an arc-spreading center intersection.