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

Detailed knowledge of the seismic structure, fabric, and dynamics that surround the oceanic LAB continue to be refined through offshore seismic studies. Previous high-resolution studies in the Pacific basin far from plate boundaries show asthenospheric fabric that aligns neither with the lithospheric fabric (the paleo-spreading direction) nor with absolute plate motion, but rather in between. Here we present preliminary results from the Blanco Transform and Cascadia Initiative experiments, investigating the structure of the Juan de Fuca and Pacific plates on either side of the Blanco Transform. We measure ambient-noise and teleseismic Rayleigh-wave phase velocities, and solve for the period-dependent azimuthal anisotropy on either side of the transform. We will contextualize and interpret the fabrics based on mantle flow inferred from these previous Pacific basin studies.&#160;

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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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Paleomagnetic evidence of northward movement of the Pacific plate in deep-sea cores from the Central Pacific Basin

Earth and Planetary Science Letters ◽

10.1016/0012-821x(74)90060-0 ◽

1974 ◽

Vol 22 (1) ◽

pp. 22-28 ◽

Cited By ~ 16

Author(s):

S.R. Hammond ◽

F. Theyer ◽

G.H. Sutton

Keyword(s):

Deep Sea ◽

Pacific Plate ◽

Pacific Basin ◽

Central Pacific ◽

The Pacific

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

BSGF - Earth Sciences Bulletin ◽

10.2113/176.2.135 ◽

2005 ◽

Vol 176 (2) ◽

pp. 135-150 ◽

Cited By ~ 39

Author(s):

Hervé Guillou ◽

René C. Maury ◽

Sylvain Blais ◽

Joseph Cotten ◽

Christelle Legendre ◽

...

Keyword(s):

Linear Chain ◽

Age Distribution ◽

French Polynesia ◽

Temporal Variations ◽

Pacific Plate ◽

Plate Motion ◽

Age Progression ◽

Plate Velocity ◽

Time Space ◽

The Pacific

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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Absolute migration of Pacific basin mid-ocean ridges since 85 Ma and their tectonic implications for the Pacific plate

Tanzania Journal of Science ◽

10.4314/tjs.v34i1.44291 ◽

2009 ◽

Vol 34 (1) ◽

Author(s):

DCP Masalu

Keyword(s):

Pacific Plate ◽

Pacific Basin ◽

Ocean Ridges ◽

Tectonic Implications ◽

The Pacific

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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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