Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction

Abstract

We compiled the most relevant data acquired throughout the Philippine Sea Plate (PSP) from the early expeditions to the most recent. We also analyzed the various explanatory models in light of this updated dataset. The following main conclusions are discussed in this study.(1) The Izanagi slab detachment beneath the East Asia margin around 60-55 Ma likely triggered the Oki-Daito plume occurrence, Mesozoic proto-PSP splitting, shortening and then failure across the paleo-transform boundary between the proto-PSP and the Pacific Plate, Izu-Bonin-Mariana subduction initiation and ultimately PSP inception. (2) The initial splitting phase of the composite proto-PSP under the plume influence at ∼54-48 Ma led to the formation of the long-lived West Philippine Basin and short-lived oceanic basins, part of whose crust has been ambiguously called "fore-arc basalts" (FABs). (3) Shortening across the paleo-transform boundary evolved into thrusting within the Pacific Plate at ∼52-50 Ma, allowing it to subduct beneath the newly formed PSP, which was composed of an alternance of thick Mesozoic terranes and thin oceanic lithosphere. (4) The first magmas rising from the shallow mantle corner, after being hydrated by the subducting Pacific crust beneath the young oceanic crust near the upper plate spreading centers at ∼49-48 Ma were boninites. Both the so-called FABs and the boninites formed at a significant distance from the incipient trench, not in a fore-arc position as previously claimed. The magmas erupted for 15 m.y. in some places, probably near the intersections between back-arc spreading centers and the arc. (5) As the Pacific crust reached greater depths and the oceanic basins cooled and thickened at ∼44-45 Ma, the composition of the lavas evolved into high-Mg andesites and then arc tholeiites and calc-alkaline andesites. (6) Tectonic erosion processes removed about 150-200 km of frontal margin during the Neogene, consuming most or all of the Pacific ophiolite initially accreted to the PSP. The result was exposure of the FABs, boninites, and early volcanics that are near the trench today. (7) Serpentinite mud volcanoes observed in the Mariana fore-arc may have formed above the remnants of the paleo-transform boundary between the proto-PSP and the Pacific Plate.

Depositional setting, provenance, and tectonic-volcanic setting of Eocene–Recent deep-sea sediments of the oceanic Izu–Bonin forearc, northwest Pacific (IODP Expedition 352)

“…One interpretation is that FAB exclusively erupted during subduction initiation. An alternative (Lallemand 2016) is that the Amami Sankaku Basin basalt relates to early-stage backarc rifting of the Western Philippine Basin (at a high angle with respect to the IMB forearc). The rift magmatism could have been influenced by the Manus plume (Ishizuka et al 2013; see also Hickey-Vargas 2005; Savov et al 2006;Fletcher and Wyman 2015;Wu et al 2016).…”

Basement-involved faults and deep structures in the West Philippine Basin: constrains from gravity field

“…One of the most remarkable results is that the hot spot track of the Benham Rise-Urdaneta-Oki-Daito oceanic plateau (Ishizuka et al 2013;Wu et al 2016) made an out-clear response on the regional gravity field, and we can see the bold outlines of the Benham Rise, the Urdaneta plateau and the Oki-Daito Rise. Especially in the vicinity of the hot spot track, the disorganized fabrics of the volcanic excess (Ishizuka et al 2013;Lallemand 2016;Wu et al 2016) are also well exposed. We can directly and easily clear out the sphere of the volcanisms caused by the Manus plume during the nucleating and opening of the WPB from about 52 to 36 Ma (Wu et al 2016).…”

Boninite and boninite-series volcanics in northern Zambales ophiolite: Doubly-vergent subduction initiation along Philippine Sea Plate margins

“…Although it is beyond the scope of this study to identify the nature of a pre-existing structural boundary as a transform fault or strike-slip extension of a subduction zone, we note that 25 both Zambales and IBM are orthogonal to the West Philippine Basin spreading center and the Cretaceous arc terranes in the overriding plate. Contrary to a subduction initiation origin, Lallemand (2016) posits that proto-arc basalts (or forearc basalts) formed in short lived Eocene oceanic basins (e.g. Kita-Daito and Minami-Daito basins) bounded by the Cretaceous arc terranes.…”

“…East of Luzon and forming the greater part of Philippine Sea Plate, the West Philippine Basin (WPB) is characterized as a back-arc basin formed between opposing subduction zones (Deschamps and Lallemand, 2002). Pre-Eocene subduction south of WPB possibly generated the Mesozoic arc terranes in the Philippine Sea Plate including Amami Plateau and Daito ridge as well as the Cretaceous 10 ophiolites in eastern Philippines (Lallemand, 2016). Initiation of a long-lived subduction east of WPB produced the IzuOgasawara (Bonin)-Mariana (IBM) forearc (Ishizuka et al, 2011).…”

“…Amami plateau, Daito Ridge) possibly sharing a common history as the overriding plate prior to initiation of subduction (Deschamps and Lallemand, 2002;Lallemand, 2016). Therefore, juxtaposed…”