Age progression along the Society hotspot chain (French Polynesia) based on new unspiked K-Ar ages

Abstract New K-Ar dates of volcanic rocks from five of the nine islands of the Society Archipelago (Moorea, Huahine, Raiatea, Bora Bora and Maupiti), confirm a Pacific plate velocity of around 11 cm/a during the last 4.3 m.y. These new data allow us to analyse the age-distance relationship along the chain and to evaluate possible temporal variations in the activity of the Society hotspot. A clear increase of ages is observed along the linear chain away from the present Society hotspot location. The time-space relationship between Taiarapu, Tahiti-Nui and Moorea can be explained by a simple hotspot model. Nevertheless, the simple fixed hotspot model assuming constant Pacific plate velocity may need adjustments to fully explain the age progression along the Archipelago. The slight departures from a linear age distribution can be explained by changes in Pacific plate motion which occurred at 5 and 3 Ma. In addition, the contemporaneous magmatic activities in the pairs Bora-Bora/Tahaa, Raiatea/Huahine, Maiao/Moorea require additional lithospheric control on magma transport. Combined with the hotspot activity, lithospheric loading may have produced extension and triggered volcanism along already existing fractures linking paired islands. The most likely model for the Society chain, proposed by McNutt [1998], involves a plume originating from a wide deep thermally anomalous zone (the Pacific Superswell) as a rising diapir (hotspot of secondary type according to the classification of Courtillot et al. [2003]). It melted during ascent and ponded beneath the Pacific plate to form short linear island chains showing rather good age vs. distance correlations.

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Various Ages of Recycled Material in the Source of Cenozoic Basalts in SE China: Implications for the Role of the Hainan Plume

Journal of Petrology ◽

10.1093/petrology/egaa060 ◽

2020 ◽

Vol 61 (6) ◽

Author(s):

Yan-Qing Li ◽

Hiroshi Kitagawa ◽

Eizo Nakamura ◽

Changqian Ma ◽

Xiangyun Hu ◽

...

Keyword(s):

Subduction Zone ◽

Pacific Plate ◽

Late Cenozoic ◽

Rock Composition ◽

Se Asia ◽

Time Space ◽

The Pacific ◽

Different Ages ◽

Se China ◽

Basaltic Lavas

Abstract Subduction processes introduce crustal materials into the mantle, and mantle plumes return them to the surface. However, when and how the subducted materials were recorded in the plume-related basalts remains unclear. Here we investigate geochronology, bulk-rock composition, and Sr–Nd–Pb isotopes of Cenozoic basalts from Southeast China, occurring near the west Pacific subduction zone and the seismically detected Hainan plume. Volcanism beginning in the late Oligocene in the continental margin of SE China consistently becomes younger landward. Together with a compilation of published results on the synchronous basalts from the South China Sea seamounts and the Indochina peninsula, the volcanoes close to the Pacific subduction zone exhibit more radiogenic Pb and Sr isotopes associated with less radiogenic Nd isotopes compared with those of the inland volcanoes. Such spatiotemporal variations in radiogenic isotopes imply oceanic crusts of different ages in the source, each corresponding to a different geographical volcanic belt. Major-element features such as low CaO, high TiO2 and high Fe/Mn ratios imply that pyroxenite/eclogite could serve as a source lithology of the SE China basalts. Specific trace-element signatures reveal the important roles of recycled oceanic crust along with surface sediment, which was inconsistently dehydrated during subduction. A geologically, geochemically, and geophysically plausible scenario is proposed to illustrate the time–space–source correlation of the late Cenozoic basaltic lavas in SE Asia. The Hainan plume delivered the ancient subducted crust (1·5 Ga) from the core–mantle boundary and, subsequently, the subducted Pacific plate crustal materials from the mantle transition zone to the shallow mantle as a result of mantle convection induced by continuous subduction of the Pacific plate. Such recycled materials of different ages contributed to the geographical compositional heterogeneities of the late Cenozoic basaltic lavas in SE Asia.

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Relative Plate Motion between the Eurasian Plate and the Pacific Plate at the Japan Trench

Zisin (Journal of the Seismological Society of Japan 2nd ser ) ◽

10.4294/zisin1948.33.1_95 ◽

1980 ◽

Vol 33 (1) ◽

pp. 95-97

Author(s):

Takao EGUCHI

Keyword(s):

Pacific Plate ◽

Plate Motion ◽

Japan Trench ◽

Eurasian Plate ◽

The Pacific ◽

Relative Plate Motion

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Pacific Plate slab pull and intraplate deformation in the early Cenozoic

Solid Earth Discussions ◽

10.5194/sed-6-145-2014 ◽

2014 ◽

Vol 6 (1) ◽

pp. 145-190 ◽

Cited By ~ 1

Author(s):

N. P. Butterworth ◽

R. D. Müller ◽

L. Quevedo ◽

J. M.O'Connor ◽

K. Hoernle ◽

...

Keyword(s):

Large Scale ◽

Driving Forces ◽

Plate Boundary ◽

Pacific Plate ◽

Plate Motion ◽

Age Progression ◽

Intraplate Volcanism ◽

Intraplate Deformation ◽

Lithospheric Extension ◽

Early Cenozoic

Abstract. Large tectonic plates are known to be susceptible to internal deformation, leading to a range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific Plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its north-western perimeter, causing lithospheric extension along pre-existing weaknesses. Large scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau, and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians Volcanic Ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific absolute plate motions, and cannot be responsible for the Hawaii-Emperor Bend (HEB), confirming previous interpretations that the 47 Ma HEB does not reflect an absolute plate motion event.

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The Mode of Trench-Parallel Subduction of the Middle Ocean Ridge

Frontiers in Earth Science ◽

10.3389/feart.2021.781117 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xiaobing Shen ◽

Wei Leng

Keyword(s):

Evolutionary Process ◽

Pacific Plate ◽

North American Plate ◽

Plate Motion ◽

Western Boundary ◽

Ridge Subduction ◽

Ocean Ridges ◽

The Pacific ◽

Mid Ocean Ridge ◽

Ocean Ridge

Trench-parallel subduction of mid-ocean ridges occurs frequently in plate motion history, such as along the western boundary of the Pacific plate in the early Cenozoic and along the eastern boundary of the Pacific plate at present. Such subduction may strongly alter the surface topography, volcanic activity and slab morphology in the mantle, whereas few studies have been conducted to investigate its evolutionary process. Here, we construct a 2-D viscoelastoplastic numerical model to study the modes and key parameters controlling trench-parallel subduction of mid-ocean ridges. Our model results show that the subduction modes of mid-ocean ridges can be primarily categorized into three types: the fast spreading mode, the slow spreading mode, and the extinction mode. The key factor controlling these subduction modes is the relative motion between the foregoing and the following oceanic plates, which are separated by the mid-ocean ridge. Different subduction modes exert different surface geological expressions, which may explain specific evolutionary processes related to mid-ocean ridge subduction, such as topographic deformation and the eruption gap of volcanic rocks in East Asia within 55–45 Ma and in the western North American plate during the late Cenozoic.

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Two new species of Foa (Apogonidae) from the Pacific Plate, with redescriptions of Foa brachygramma and Foa fo

Zootaxa ◽

10.11646/zootaxa.2988.1.1 ◽

2011 ◽

Vol 2988 (1) ◽

pp. 1 ◽

Cited By ~ 3

Author(s):

THOMAS H. FRASER ◽

JOHN E. RANDALL

Keyword(s):

New Species ◽

Hawaiian Islands ◽

French Polynesia ◽

The Philippines ◽

Pacific Plate ◽

Marshall Islands ◽

Gill Rakers ◽

The Pacific ◽

Anterior Body ◽

A New Species

Species of the Indo-Pacific apogonid fish genus Foa known from the Pacific Plate are reviewed. The type species of Foa, F. brachygramma, is redescribed including information on the distribution of lateralis canal pores and free neuromasts on the head, body and caudal fin. This species, formerly ascribed as having a wide Indo-Pacific distribution, is restricted to the Hawaiian Islands. Foa fo, type locality Philippines, with an apparent Indo-Pacific distribution (but not the Hawaiian Islands), has 12–15 gill rakers (14–16 for F. brachygramma), and four or five irregular dark bars and whitish spots on the head and body (F. brachygramma has dark edging on the scales and lacks whitish spots). A lectotype from the Philippines is selected for Foa fo. Foa leisi is described as a new species from French Polynesia, olivaceous with three faint brown bars on body, one under each dorsal fin and on anterior on caudal peduncle; head and anterior body with dark-edged whitish spots. Foa nivosa is described as new species from Palau, Marshall Islands and Fiji, pale yellowish tan with numerous red-edged whitish spots, smaller on head. The axial skeletons are compared for Foa brachygramma, F. fo, F. hyalina, F. leisi, and F. nivosa. Foa madagascariensis and its synonym Apogonichthys zuluensis are not treated here, but Petit’s species is recognized as valid. The following characters can be used to identify species: color patterns, pored lateral-line scales as they vary with standard length, number of gill rakers and rudiments, mandibular pore and certain free neuromast patterns.

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A new GPS velocity field for the Pacific Plate – Part 1: constraints on plate motion, intraplate deformation, and the viscosity of Pacific basin asthenosphere

Geophysical Journal International ◽

10.1093/gji/ggu341 ◽

2014 ◽

Vol 199 (3) ◽

pp. 1878-1899 ◽

Cited By ~ 10

Author(s):

C. DeMets ◽

Bertha Márquez-Azúa ◽

Enrique Cabral-Cano

Keyword(s):

Velocity Field ◽

Pacific Plate ◽

Plate Motion ◽

Pacific Basin ◽

Intraplate Deformation ◽

The Pacific ◽

Gps Velocity Field

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Pacific plate slab pull and intraplate deformation in the early Cenozoic

Solid Earth ◽

10.5194/se-5-757-2014 ◽

2014 ◽

Vol 5 (2) ◽

pp. 757-777 ◽

Cited By ~ 12

Author(s):

N. P. Butterworth ◽

R. D. Müller ◽

L. Quevedo ◽

J. M. O'Connor ◽

K. Hoernle ◽

...

Keyword(s):

Large Scale ◽

Driving Forces ◽

Plate Boundary ◽

Pacific Plate ◽

Plate Motion ◽

Age Progression ◽

Intraplate Volcanism ◽

Intraplate Deformation ◽

Lithospheric Extension ◽

Early Cenozoic

Abstract. Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma, subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its northwestern perimeter, causing lithospheric extension along pre-existing weaknesses. Large-scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians volcanic ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific absolute plate motion directions, and cannot be responsible for the Hawaiian–Emperor bend (HEB), confirming previous interpretations that the 47 Ma HEB does not primarily reflect an absolute plate motion event.

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Relative Timing of the Eocene Global Reorganization of Plate Motions: New Results for Pacific Plate Hotspot Tracks

10.5194/egusphere-egu21-13574 ◽

2021 ◽

Author(s):

Kevin Gaastra ◽

Richard Gordon

Keyword(s):

Pacific Plate ◽

Western Pacific ◽

Plate Motion ◽

Inversion Method ◽

Plate Boundaries ◽

Plate Motions ◽

The Pacific ◽

Significant Difference ◽

Deep Earth ◽

Earth Dynamics

To improve modeling of deep-earth dynamics it is important to understand changes in the arrangements of plate boundaries, especially trenches accommodating subduction, and major changes in tectonic plate motion. Here we focus on the sequence of key surface events in Eocene time that likely coincide with changes in deep-earth dynamics. In particular, we develop methods of analysis of seamount locations and age dates using a small number of adjustable parameters (10 per chain) on the Pacific plate with a focus on the timing of the Hawaiian-Emperor bend relative to the timing of other major Eocene tectonic changes. We find that motion between hotspots differs insignificantly from zero with rates of 2&#177;4 mm/a (&#177;2&#963;) for 0-48 Ma and 26&#177;34 mm/a (&#177;2&#963;) for 48-80 Ma. Relative to a mean Pacific hotspot reference frame, nominal rates of motion of the Hawaii, Louisville, and Rurutu hotspots are ~5 mm/a and differ insignificantly from zero. We conclude that plumes underlying these Pacific hotspots are more stable in a convecting mantle than previously inferred. We estimate the locations and ages (with uncertainties) of bends in Pacific hotspot chains using a novel inversion method. The location of the ~60&#176; change in trend at the Hawaiian-Emperor bend is well constrained within ~50-80 km (=2&#963;), but the location of the bends in the Louisville and Rurutu hotspots are more uncertain. If the uncertainty in the location of the bend in the Louisville chain is included, we find no significant difference in age between the bends of different Pacific hotspot chains. The best-fitting assumed-coeval age for the bends is 47.4&#177;1.0 Ma (&#177;2&#963;), which is indistinguishable from the age of the C21o geomagnetic reversal. The age of the bend is younger than the initiation of subduction in the Western Pacific, but approximately coeval with changes in Pacific and circum-Pacific relative plate motion. Changes to the tectonic system near the age of the bend are not limited to the Pacific basin. The smooth-rough transition flanking the Carlsberg Ridge records a threshold in the decreasing spreading rate between India and Africa, thought to record the onset of the collision of India with Eurasia, and is constrained to be between C21y and C20o (46 Ma and 43 Ma) in age. Nearly simultaneously, South America and Australia began to diverge more rapidly from Antarctica. The Eocene bend in Pacific hotspot chains may be the most evident feature recording a global re-organization of plate motions and mantle circulation possibly caused by the earlier collision of India and Eurasia or initiation of western Pacific subduction.

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