scholarly journals Pacific plate slab pull and intraplate deformation in the early Cenozoic

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 757-777 ◽  
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.

scholarly journals Pacific Plate slab pull and intraplate deformation in the early Cenozoic

2014 ◽  
Vol 6 (1) ◽  
pp. 145-190 ◽  
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.

scholarly journals Intraplate volcanism triggered by bursts in slab flux

2020 ◽  
Vol 6 (51) ◽  
pp. eabd0953
Author(s):  
Ben R. Mather ◽  
R. Dietmar Müller ◽  
Maria Seton ◽  
Saskia Ruttor ◽  
Oliver Nebel ◽  
...  
Keyword(s):  
Transition Zone ◽  
Plate Tectonics ◽  
Isotope Geochemistry ◽  
Plate Boundary ◽  
Oceanic Lithosphere ◽  
Mantle Transition Zone ◽  
Age Progression ◽  
Intraplate Volcanism ◽  
Enriched Mantle ◽  
Eastern Australia

Long-lived, widespread intraplate volcanism without age progression is one of the most controversial features of plate tectonics. Previously proposed edge-driven convection, asthenospheric shear, and lithospheric detachment fail to explain the ~5000-km-wide intraplate volcanic province from eastern Australia to Zealandia. We model the subducted slab volume over 100 million years and find that slab flux drives volcanic eruption frequency, indicating stimulation of an enriched mantle transition zone reservoir. Volcanic isotope geochemistry allows us to distinguish a high-μ (HIMU) reservoir [>1 billion years (Ga) old] in the slab-poor south, from a northern EM1/EM2 reservoir, reflecting a more recent voluminous influx of oceanic lithosphere into the mantle transition zone. We provide a unified theory linking plate boundary and slab volume reconstructions to upper mantle reservoirs and intraplate volcano geochemistry.

scholarly journals Taking time to twist a continent—Multistage origin of the New Zealand orocline

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 56-60
Author(s):  
S. Lamb ◽  
N. Mortimer
Keyword(s):  
New Zealand ◽  
Large Scale ◽  
Plate Boundary ◽  
Plate Motion ◽  
West Antarctica ◽  
Alpine Fault ◽  
Plate Rotation ◽  
Dextral Shear ◽  
Plate Boundary Zone ◽  
Two Sides

Abstract In New Zealand, a giant coherent “Z” shape is defined by several curvilinear pre-Cenozoic basement terranes that extend across Zealandia for >1500 km along strike. It is widely assumed that this curvature was the result of bending during the Neogene, which together with ∼450 km of dextral displacement on the Alpine fault accommodated a total of ∼750 km of dextral shear through the New Zealand plate boundary zone between the Australian and Pacific plates. This would make it a very simple form of orocline. In fact, we show that its development was surprisingly complex and protracted, with a composite origin. Its western and southern parts were bent as much as 70° in the Mesozoic. In the Late Cretaceous, the already bent terranes were offset sinistrally by ∼250 km along the cross-cutting proto–Alpine fault, which acted as a transform to the rift between East and West Antarctica. Since the Eocene, and after Zealandia had completely separated from Antarctica, the two sides of the Alpine fault have undergone 45° of relative plate rotation, further bending the terranes. However, the eastern part of what appears today to be the same oroclinal structure has been created entirely since the Eocene, and mainly during the Neogene phase of dextral shear through the plate boundary, with large-scale internal bending and shortening. We suggest that multistage and composite evolutions may be typical features of oroclines, which would be difficult to unravel without a rich tectonic and plate motion database, such as that available for the New Zealand region.

scholarly journals Intraplate volcanism triggered by bursts in slab flux

2021 ◽  
Author(s):  
Ben Mather ◽  
Dietmar Muller ◽  
Maria Seton ◽  
Saskia Ruttor ◽  
Oliver Nebel ◽  
...  
Keyword(s):  
Transition Zone ◽  
Plate Tectonics ◽  
Isotope Geochemistry ◽  
Plate Boundary ◽  
Oceanic Lithosphere ◽  
Mantle Transition Zone ◽  
Age Progression ◽  
Intraplate Volcanism ◽  
Eastern Australia ◽  
Mafic Volcanism

<p><span><span>Long-lived, widespread intraplate volcanism without age progression is one of the most controversial features of plate tectonics. The eastern margin of Australia and Zealandia has experienced extensive mafic volcanism </span><span>over the last 100 million years</span><span>. A plume origin has been proposed for </span><span>three distinct chains of volcanoes,</span> <span>however</span><span>, the majority of eruptions exhibit no clear age progression. Previously proposed edge-driven convection, asthenospheric shear, and lithospheric detachment fail to explain the non age-progressive eruptions </span><span>across the </span><span>~5000 km wide intraplate volcanic province from Eastern Australia to Zealandia. We model the subducted slab volume over 100 million years and find that slab flux drives volcanic eruption frequency, indicating stimulation of an enriched mantle transition zone reservoir. Volcanic isotope geochemistry allows us to distinguish a HIMU reservoir (>1 Ga old) in the slab-poor south, from a northern EM1/EM2 reservoir, reflecting a more recent voluminous influx of oceanic lithosphere into the mantle transition zone. We provide a unified theory linking plate boundary and slab volume reconstructions to upper mantle reservoirs and intraplate volcano geochemistry.</span></span></p>

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

2005 ◽  
Vol 176 (2) ◽  
pp. 135-150 ◽  
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.

scholarly journals Simultaneous Inference of Plate Boundary Stresses and Mantle Rheology Using Adjoints: Large-Scale Two-Dimensional Models

2021 ◽  
Author(s):  
Johann Rudi ◽  
Michael Gurnis ◽  
Georg Stadler
Keyword(s):  
Large Scale ◽  
Plate Boundary ◽  
Optimization Method ◽  
Plate Motion ◽  
Rheological Parameters ◽  
Shear Stresses ◽  
Plate Boundaries ◽  
Mantle Dynamics ◽  
Motion Data ◽  
Mantle Rheology

Plate motions are a primary surface constraint on plate and mantle dynamics and rheology, plate boundary stresses, and the occurrence of great earthquakes. Within an optimization method, we use plate motion data to better constrain uncertain mantle parameters. For the optimization problem characterizing the maximum a posteriori rheological parameters we derive gradients using adjoints and expressions to approximate the posterior distributions for stresses within plate boundaries. We apply these methods to a 2-D cross section from the western to eastern Pacific, with temperature distributions and fault zone geometries developed primarily from seismic and plate motion data. We find that the best-fitting stress exponent, $n$, is about 2.8 and the yield stress about 100 MPa or less. The normal stress on the interplate fault zones is about 100 MPa and the shear stresses about 10 MPa or less.

scholarly journals Land Use Transition and Driving Forces in Chinese Loess Plateau: A Case Study from Pu County, Shanxi Province

Land ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 67
Author(s):  
Han Huang ◽  
Yang Zhou ◽  
Mingjie Qian ◽  
Zhaoqi Zeng
Keyword(s):  
Land Use ◽  
Food Security ◽  
Loess Plateau ◽  
Large Scale ◽  
Driving Forces ◽  
Chinese Loess Plateau ◽  
Shanxi Province ◽  
Forest Land ◽  
Land Use Transition ◽  
Macro Scale

Land use transition is essentially one of the manifestations of land use/cover change (LUCC). Although a large number of studies have focused on land use transitions on the macro scale, there are few studies on the micro scale. Based on the data of two high-resolution land use surveys, this study used a land use transfer matrix and GeoDetector model to explore the spatial-temporal patterns and driving forces of land use transitions at the village level in Pu County over a ten-year period. Results show that Pu County has experienced a drastic process of land use transition. More than 80% of cropland and grassland have been converted to forest land, and over 90% of the expansion of built-up land came from the occupation of forest land, cropland, and grassland. The driving forces of land use transition and its magnitude depended on the type of land use. The implementation of the policy of returning farmland to forest, or grain-for-green (GFG) was the main driving force for the large-scale conversion of cultivated land to forest land in Pu County. In the context of policy of returning farmland to forests, the hilly and gully regions of China’s Loess Plateau must balance between protecting the ecology and ensuring food security. Promoting the comprehensive consolidation of gully land and developing modern agriculture may be an important way to achieve a win-win goal of ecological protection and food security.

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