Benham Rise unveiled: Morphology and structure of an Eocene large igneous province in the West Philippine Basin

Barretto, Jenny Anne L.; Wood, Ray; Milsom, John

doi:10.1016/j.margeo.2019.106052

Cited by 17 publications

(17 citation statements)

References 80 publications

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“…The most active volcanism stage was between 50 and 41 Ma, and the magma supply continued to 26 Ma. Between 41 and 26 Ma, the UP separated from the BR, which is consistent with the N–S trending second spreading episode 16 . In addition, a V-shaped seamount chain was reported 6 , which is a propagating rift that occurred to the west of the LOFZ.…”

Section: Introductionsupporting

confidence: 76%

“…In our study area, most Moho reflections show medium amplitudes and discontinuous patterns, which is consistent with the crustal accretion by the mantle plume or the hotspot interacting with the seafloor spreading origin. The BR to the east of the LOFZ, located in the southwestern Philippine Sea Plate, was identified as a local hotspot developing a 15-km-thick oceanic crust during the Early to Middle Eocene 16 . Compared to the BR, the relatively thin crustal thickness (12.7 km) of the GR, which developed in the same period as the BR (i.e., Middle to Early Eocene), is located to the west of the LOFZ.…”

Section: Discussionmentioning

confidence: 99%

“…The geochemistry analysis determined the BR and UP are originated from Oki-Daito mantle plume. In addition to the latest multichannel seismic and gravity modeling study suggests that the volcanism of the BR is likely the origin of the magmatic spreading episode 16 . The most active volcanism stage was between 50 and 41 Ma, and the magma supply continued to 26 Ma.…”

Section: Introductionmentioning

confidence: 93%

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Separation of Gagua Rise from Great Benham Rise in the West Philippine Basin during the Middle Eocene

Yeh

Lin

Hsu

et al. 2021

Sci Rep

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The West Philippine Basin (WPB) has started opening at ~ 58 Ma and ceased spreading at ~ 33 Ma, developing a fast spreading (~ 44 mm/yr half-spreading rate) magmatic episode between 58 and 41 Ma and the second amagmatic episode between 41 and 33 Ma. The occurrence of the first stage of spreading is closely related to the Oki-Daito mantle plume and related Benham Rise (BR) and Urdaneta Plateau (UP) activity. To the east of the Luzon–Okinawa Fracture Zone (LOFZ), BR was the most active volcanism from 48 to 41 Ma. The geomagnetic ages on both sides of the LOFZ have been determined; however, their causal relationship and evolution in the WPB remain unclear. In this study, we performed integrated analyses of multichannel seismic data and swath bathymetry data for the area to the west of the LOFZ. To the west of the LOFZ, the Gagua Rise (GR), is identified by a high residual free-air gravity anomaly, volcanic seamount chains and an overlapping spreading center. The GR is located at magnetic isochrons C20/C22 (50 to 44 Ma) and shows a thick oceanic crust of at least 12.7 km. We first propose an oceanic plateau named Great Benham Rise (GBR) which includes GR, UP and BR. We infer that the GR was a portion of the GBR since ~ 49 Ma and was separated from the GBR at ~ 41 Ma by the right-lateral LOFZ motion. Later, the relict GBR magmatism only continued in the area to the east of the LOFZ. Overall, the GBR dominates the spreading history of the WPB.

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Section: Introductionsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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Separation of Gagua Rise from Great Benham Rise in the West Philippine Basin during the Middle Eocene

Yeh

Lin

Hsu

et al. 2021

Sci Rep

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“…The basalts from site 100DS and sites IODP 292, 294, and 446 have a similar geodynamic background, which was affected by a mantle plume. Recent studies have shown that magma with a surface area of about 0.11 Mkm 2 and a volume of 0.13 Mkm 3 extruded within 5 Myr, and the geochemical characteristics of the basalts from the Benham Rise are similar to OIB, indicating that the Benham Rise is likely a large igneous province [76]. In addition, the morphology of the Benham Rise and the thicker crust (about 15 km) calculated from the gravity anomalies beneath the Benham Rise supports the viewpoint that the volcanism is attributed to the interaction between a hotspot (or mantle plume) and a spreading ridge.…”

Section: Tectonic Setting and Geological Evolutionmentioning

confidence: 99%

“…During this period, Benham Rise was formed on the south-west side of the spreading center, and a chain of age-progressive oceanic Plateaus (Urdaneta Plateau) was formed on the north-east side of the spreading center of WPB (Figure 15(c)) [13]. At about 35 Ma, the spreading center jumped to northeast of Oki-Daito plume, forming a chain of Seamounts (e.g., Toog Seamount, Santos Seamount, and Akle Seamount) in the south-west of the spreading center (Figure 15(d)) [76]. However, the ages of these Seamounts are unknown, which hinder us to understand the effect of the Oki-Daito plume.…”

Section: Tectonic Setting and Geological Evolutionmentioning

confidence: 99%

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

et al. 2020

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Since the early Cenozoic, the West Philippine Basin (WPB) and the whole Philippine Sea Plate (PSP) has undergone a complex geological evolution. In this study, we presented K-Ar ages, in situ trace element, and major element compositions of minerals of basalts collected from the Benham Rise and the Central Basin Fault (CBF) in the WPB, to constrain their magmatic process and regional geological evolution. Olivine phenocrysts and microlites in the alkali basalts (20.9 Ma) from the Benham Rise have forsterite (Fo) contents of 56.90%–76.10% and 53.13%-66.41%, respectively. The clinopyroxenes in the tholeiites (29.1 Ma) from the CBF is predominantly diopside and augite, and it is depleted in light rare earth elements (LREEs) (LaN/YbN=0.13–3.40) and large-ion lithophile elements (LILEs). The plagioclases in the basalts from both of the Benham Rise and the CBF are predominantly labradorite and andesine, with a minor amount of bytownite, and it is enriched in LREEs, Ba, Sr, and Pb and exhibits strong positive Eu anomalies. However, there exist obvious differences in plagioclase compositions between these two tectonic sites. The source lithology of the Benham Rise basaltic rocks could be garnet pyroxenite, and yet that of the CBF could be spinel-lherzolite. The calculated mantle potential temperature beneath the Benham Rise is 1439°C–1473°C, which is significantly higher than that beneath the CBF (1345°C–1381°C), suggesting there existed thermal anomaly beneath the Rise during basaltic magmatism. This study also calculated the temperature and pressure of the clinopyroxenes and plagioclases, which have been used to indicate magmatic processes. Finally, we suggest that the Benham Rise basaltic rocks may be related to a mantle plume (e.g., the Oki-Daito mantle plume), and the CBF was once located in a back-arc spreading center behind an active subduction zone. The extinction of the Oki-Daito mantle plume activity might be at about 20.9 Ma, and cessation of the back-arc spreading of WPB was at about 29.1 Ma or younger.

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Large Igneous Province Record Through Time and Implications for Secular Environmental Changes and Geological Time‐Scale Boundaries

Ernst

Bond

Zhang

et al. 2021

Geophysical Monograph Series

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Large igneous provinces are voluminous (> 0.1 Mkm 3 ( = 10 6 km 3 ); frequently above 1 Mkm 3 ), mainly mafic (ultramafic) magmatic events of intraplate affinity (based on tectonic setting and/or geochemistry) that occur in both continental and oceanic settings, are often linked with mantle plumes, and are typically emplaced over a short time period ( < 5 myr; often < 2 myr) or in multiple short pulses with a maximum duration of a few tens of myr (e.g.,

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Benham Rise unveiled: Morphology and structure of an Eocene large igneous province in the West Philippine Basin

Cited by 17 publications

References 80 publications

Separation of Gagua Rise from Great Benham Rise in the West Philippine Basin during the Middle Eocene

Separation of Gagua Rise from Great Benham Rise in the West Philippine Basin during the Middle Eocene

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

Large Igneous Province Record Through Time and Implications for Secular Environmental Changes and Geological Time‐Scale Boundaries

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