Origin and Age of Magmatism in the Northern Philippine Sea Basins. (7th April 2022)

• Record Type: Journal Article
• Authors: Ishizuka, Osamu; Tani, Kenichiro; Taylor, Rex N.; Umino, Susumu; Sakamoto, Izumi; Yokoyama, Yuka; Shimoda, Gen; Harigane, Yumiko; Ohara, Yasuhiko; Conway, Chris E.; Perez, Americus; Sekimoto, Shun
• Is Part Of: Geochemistry, geophysics, geosystems. Volume 23:Number 4(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-07
• Subjects: Philippine Sea -- Kita‐Daito Basin -- rifting -- subduction initiation; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 550.5
• DOI: 10.1029/2021GC010242
• Languages: English
• ISSNs: 1525-2027

Abstract

Abstract: A Robust tectonic reconstruction of the Philippine Sea Plate around ∼52 Ma is a prerequisite in understanding the process of subduction initiation and establishment of the Izu‐Bonin‐Mariana arc. This study investigates origins and timing of basin formation in the still poorly understood oldest part of the northern Philippine Sea plate. We have established that andesitic magmatism in the form of the Northern Philippine Sea volcanics is widely distributed across this area. It is founded on both a Mesozoic arc terrane (Daito Ridge Group) and an intervening basin (Kita‐Daito Basin). Their narrow Eocene age range (45‐41 Ma) and lack of systematic spatial variation in geochemistry implies that this magmatism was not associated with on‐going subduction, but related to the rifting/spreading event forming the Kita‐Daito Basin. The arc‐like geochemistry of the volcanics seems to indicate melting of lithospheric mantle which had been previously metasomatized by Mesozoic subduction of a plate with Pacific‐MORB isotopic characteristics. Late Eocene basaltic magmatism also found in the Kita‐Daito Basin does not have arc‐like characteristics, and could have formed from low‐degree melts of asthenospheric mantle associated with the final stage of Kita‐Daito Basin spreading. As onset of activity of the Northern Philippine Sea volcanics is essentially synchronous with the magmatism associated with the Oki‐Daito mantle plume, it is possible that both magmatism and rifting of the Kita‐Daito Basin were triggered by the arrival of the Oki‐Daito mantle plume in this region. These results demonstrate that the Kita‐Daito Basin postdates subduction initiation of the Pacific Plate along the Izu‐Bonin‐Mariana arc. Plain Language Summary: This study investigates origin and age of ocean basins in the still poorly understood northern Philippine Sea plate. This area will help us appreciate what happens during the initiation of a new destructive plate margin. We recovered rock samples from the Northern Philippine Sea Seamounts and Kita‐Daito Basin, and determined their age and composition. These volcanoes were active between 45 and 41 Ma and are found widely distributed across the older crust of the northernmost Philippine Sea Plate. Despite the geographical spread of these volcanoes, they have a similar composition across the region. This indicates they were produced during stretching of the older crust, which reactivated the older underlying upper mantle. A possible reason for this stretching may have been the impact of a mantle plume beneath this region. Key Points: Widely spread Eocene andesitic magmatism in northern Philippine Sea marks the onset of rifting in the Mesozoic arc terrane Late Eocene basalts in the Kita‐Daito Basin could represent the last stage of spreading of the Kita‐Daito Basin Rifting and spreading of the Mesozoic arc terrane in northern Philippine Sea postdate subduction initiation along the Izu‐Bonin arc