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

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

<p><span> </span><span>To improve</span><span> </span><span>modeling of</span><span> deep-earth dynamics </span><span>it is i</span><span>mportant</span><span> to understand</span><span> changes in the arrangements of plate boundaries, especially trenches accommodating subduction, </span><span>and </span><span>major </span><span>changes</span><span> in tectonic plate motion. </span><span>Here</span><span> we focus on </span><span>the sequence of </span><span>key surface events in </span><span>Eocene </span><span>time that </span><span>likely coincide with changes in </span><span>deep-earth dynamics. In particular, we </span><span>develop </span><span>methods of analysis of seamount locations and age dates using a small number of adjustable parameters (10 per chain)</span><span> on the Pacific plate </span><span>with a focus on the </span><span>timing of the </span><span>Hawaiian-Emperor bend </span><span>relative to the timing of other </span><span>major Eocene tectonic changes</span><span>. </span></p><p><span> </span><span>We find that motion between hotspots differs insignificantly from zero with rates of 2</span><span>±</span><span>4 mm/a (±2</span><span>σ</span><span>) for 0-48 Ma and 26±34 mm/a (±2σ) for 48-80 Ma. Relative to a mean Pacific hotspot reference frame, </span><span>nominal rates of </span><span>motion of the Hawaii, Louisville, and Rurutu hotspots are </span><span>~</span><span>5</span><span> mm/a and </span><span>differ insignificantly from zero</span><span>. We conclude that plumes underlying these Pacific hotspots are more stable in a convecting mantle than previously inferred.</span></p><p><span> We estimate the locations and ages (with uncertainties) of bends in Pacific hotspot chains using a novel inversion method. The location of the ~60° change in trend at the Hawaiian-Emperor bend is well constrained within ~50-80 km (=2σ), 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±1.0 Ma (±2σ), 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.</span></p>

scholarly journals Exploring the Dynamics of Global Plate Motion Based on the Granger Causality Test

2021 ◽  
Vol 11 (17) ◽  
pp. 7853
Author(s):  
Lixin Ning ◽  
Chun Hui ◽  
Changxiu Cheng
Keyword(s):  
Energy Transfer ◽  
Granger Causality ◽  
Granger Causality Test ◽  
Test Method ◽  
Plate Motion ◽  
Plate Boundaries ◽  
Causality Test ◽  
Plate Motions ◽  
The Pacific ◽  
The Relationship

The geodynamic mechanism is the research focus and core issue of plate motions and plate tectonics. Analyzing the time series of earthquakes may help us understand the relationship between two plate boundaries and further explore movement mechanisms. Therefore, this paper uses earthquake event data and the Granger causality test method to quantitatively analyze the interaction and energy transfer relationship of plate boundaries from the viewpoint of statistics. The paper aims to explore the relationship between the pull effect and the push effect of plate motion and to provide knowledge to explore seismic energy transfer relationships, and even to predict earthquakes: (1) The directions of the global plate motion field are opposite to the directions of Granger causality between plate boundaries of the Pacific, Nazca, African, Australian, Eurasian, and Philippine plates. (2) The slab-pull force (not limited to the subduction force of the ocean plates) provides a main driving force for plate motions in the Pacific plate, Nazca plate, African plate, Australian plate, Eurasian plate, and Philippine sea plate. (3) The causality relationship and optimal lag length of energy release between plate boundaries may provide another view to forecasting earthquakes.

scholarly journals Current Plate Motions

1988 ◽  
Vol 129 ◽  
pp. 351-352
Author(s):  
Richard Gordon ◽  
Charles Demets ◽  
Seth Stein ◽  
Don Argus ◽  
Dale Woods
Keyword(s):  
Subduction Zones ◽  
Continental Drift ◽  
Geophysical Data ◽  
Plate Motion ◽  
Plate Boundaries ◽  
Transform Faults ◽  
Plate Motions ◽  
Motion Data ◽  
Motion Models ◽  
Self Consistent

The standard against which VLBI measurements of continental drift and plate motions are compared are self-consistent global models of “present-day” plate motions determined from geophysical data: marine magnetic anomalies at oceanic spreading centers, azimuths of transform faults, and orientations of earthquake slip vectors on transform faults and at subduction zones. Past global plate motion models have defined regions where the assumption that plates behave rigidly has apparently lead to systematic misfits, sometimes exceeding 10 mm/yr, of plate motion data. Here, we present some of the results from NUVEL-1, a new, self-consistent global model of present-day relative plate motions determined from a compilation and analysis of existing and new geophysical data. These data and new techniques have allowed us to eliminate nearly all statistically significant systematic misfits identified by earlier models, suggesting that the rigid-plate assumption is an excellent approximation when plate motions are averaged over several million years. Beside improving estimates of the motion on previously identified plate boundaries, we have also identified and determined motions on other boundaries whose subtle morphologies, lack of seismicity, and very slow (< 10 mm/yr) relative motions have made them difficult to detect. Here we focus on the application of VLBI measurements to help resolve plate tectonic problems and then briefly outline our results for Pacific-North America motion and plate motions in the Indian Ocean.

High-resolution constraints on LAB structure at the Blanco transform

2020 ◽  
Author(s):  
William Hawley ◽  
James Gaherty
Keyword(s):  
High Resolution ◽  
Azimuthal Anisotropy ◽  
Plate Motion ◽  
Pacific Basin ◽  
Mantle Flow ◽  
Detailed Knowledge ◽  
Plate Boundaries ◽  
Seismic Structure ◽  
The Pacific ◽  
Juan De Fuca

&lt;p&gt;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.&amp;#160;&lt;/p&gt;

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

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.

Lower Yangtze drainage reorganization response to western Pacific Subduction

2020 ◽  
Author(s):  
Ping Wang ◽  
Hongbo Zheng ◽  
Yongdong Wang ◽  
Xiaochun Wei ◽  
Lingyu Tang ◽  
...  
Keyword(s):  
East Asia ◽  
Active Role ◽  
Pacific Plate ◽  
Western Pacific ◽  
Surface Processes ◽  
Silty Clay ◽  
Lithospheric Deformation ◽  
The Pacific ◽  
Lower Yangtze ◽  
Early Cenozoic

&lt;p&gt;The evolution of the longest river in Asia, Yangtze, provides a spectacular example to understand the Cenozoic interaction between tectonic, climate and surface processes. The oldest Yangtze deposits in southeast China, characterized by thick sequence of unconsolidated gravel, sand and silty clay, referred as &amp;#8220;Yangtze Gravel&amp;#8221;, has been recently found in its lower reach and dated back to &gt; 23 Ma, indicating a pre-Miocene establishment of a through-going river. However, the link between river reorganization and tectonic evolution has never been well understood. Far-field effects of the Indian&amp;#8211;Eurasia collision are often invoked to explain the widespread East Asia lithospheric deformations and the opening of the marginal, as well as the through-going of the large rivers. However,&amp;#160; some geological and geophysical investigations challenge this model and suggest that the Pacific Plate subduction beneath Eurasia plays an much more active role in East Asia lithospheric deformation during the Cenozoic. Here, we study the sedimentology, chronology and provenance of the Yangtze Gravel based on 17 stratigraphic sections exposed along the Lower Yangtze River. Our results indicate a braided alluvial system (Paleo-Lower Yangtze) established since early Miocene across the Jianghan Basin, North Jiangsu Basin and East China Sea Shelf Basin. Compared with the Early Cenozoic red-colored, halite-bearing lacustrine deposits, our results indicate a larger tectonically controlled shift from rifting to post-rift down-warping across these basins. During Early Cenozoic, the initial subduction of Pacific Plate may contribute to the back-arc extension and affect the continental deep interior of East Asia many thousands of kilometers from the subduction margin. During Oligocene to Miocene, the ongoing subduction of the Pacific plate produced a stagnant slab that may have significantly triggered the post-rift subsidence and the connection of these basins. The deposition of the &amp;#8220;Yangtze Gravel&amp;#8221; reflect the dynamic response of surface processes to western Pacific subduction in East Asia.&lt;/p&gt;

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 Kinematics and dynamics of the East Pacific Rise linked to a stable, deep-mantle upwelling

2016 ◽  
Vol 2 (12) ◽  
pp. e1601107 ◽  
Author(s):  
David B. Rowley ◽  
Alessandro M. Forte ◽  
Christopher J. Rowan ◽  
Petar Glišović ◽  
Robert Moucha ◽  
...  
Keyword(s):  
East Pacific Rise ◽  
Oceanic Lithosphere ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Boundaries ◽  
Tectonic Plates ◽  
Ocean Ridges ◽  
East Pacific ◽  
The Pacific ◽  
Negative Buoyancy

Earth’s tectonic plates are generally considered to be driven largely by negative buoyancy associated with subduction of oceanic lithosphere. In this context, mid-ocean ridges (MORs) are passive plate boundaries whose divergence accommodates flow driven by subduction of oceanic slabs at trenches. We show that over the past 80 million years (My), the East Pacific Rise (EPR), Earth’s dominant MOR, has been characterized by limited ridge-perpendicular migration and persistent, asymmetric ridge accretion that are anomalous relative to other MORs. We reconstruct the subduction-related buoyancy fluxes of plates on either side of the EPR. The general expectation is that greater slab pull should correlate with faster plate motion and faster spreading at the EPR. Moreover, asymmetry in slab pull on either side of the EPR should correlate with either ridge migration or enhanced plate velocity in the direction of greater slab pull. Based on our analysis, none of the expected correlations are evident. This implies that other forces significantly contribute to EPR behavior. We explain these observations using mantle flow calculations based on globally integrated buoyancy distributions that require core-mantle boundary heat flux of up to 20 TW. The time-dependent mantle flow predictions yield a long-lived deep-seated upwelling that has its highest radial velocity under the EPR and is inferred to control its observed kinematics. The mantle-wide upwelling beneath the EPR drives horizontal components of asthenospheric flows beneath the plates that are similarly asymmetric but faster than the overlying surface plates, thereby contributing to plate motions through viscous tractions in the Pacific region.

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