Global hotspot maps

Anderson, Don L.; Schramm, K. A.

doi:10.1130/0-8137-2388-4.19

Cited by 26 publications

(21 citation statements)

References 44 publications

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“…Transportable Array broadband seismic stations (black triangles) used in this study. Red triangles are the locations of hot spots given by Anderson and Schramm []. The plate boundaries of North America, Gorda‐Juan de Fuca, and Pacific plates are contoured in red.…”

Section: Introductionmentioning

confidence: 99%

Multiple transition zone seismic discontinuities and low velocity layers below western United States

et al. 2013

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[1] With P-to-S converted waves recorded at seismic stations of the U.S. Transportable Array, we image the fine structure of upper mantle and transition zone (TZ) beneath the western U.S. We map the topographies of seismic discontinuities by stacking data by common conversion points along profiles. Systematic depth and amplitude measurements are performed not only for the well-known "410" and "660" interfaces but also for minor seismic discontinuities identified around 350, 590, and 630 km depths. The amplitude of conversion suggests shear wave velocity (Vs) increase by 4% at the 410 and the 660. The observed 660 velocity contrast is smaller than expected from the 6% in IASP91 but consistent with a pyrolitic model of mantle composition. The Gorda plate, subducted under northern California, is tracked to the TZ where it seems to flatten and induce uplift of the 410 under northern Nevada. Maps of 410/660 amplitude/topography reveal that the TZ is anomalous beneath the geographical borders of Washington, Oregon, and Idaho, with (1) a thickened TZ, (2) a sharp change in depth of the 660, (3) a reduced 410 conversion amplitude in the North, and (4) a positive "630" discontinuity. Such anomalous structure might be inherited from the past history of plate subduction/accretion. A thinned TZ under the Yellowstone suggests higher-than-average temperatures, perhaps due to a deep thermal plume. Both the "350" and the "590" negative discontinuities extend over very large areas. They might be related either to an increased water content in the TZ, a significant amount of oceanic material accumulated through the past 100 Myr, or both.

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Section: Introductionmentioning

confidence: 99%

Multiple transition zone seismic discontinuities and low velocity layers below western United States

et al. 2013

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“…Since we are interested in the thermal evolution of the lithosphere irrespective of what drives it, removing temperatures in the lithosphere is not desirable; but in all rigor, one should discard asthenospheric temperatures in plume conduits because they are potentially hotter and may thus bias the inversions toward too large mantle temperatures (Figure ). We tested the effect of removing all tomography cells within a radius of 300 km of hot spots catalogued by [ Anderson and Schramm , ], and found no noticeable difference in the mean temperature trends and inversion results. Namely, the spatial and density inconsistencies of the data do not materially affect the results.…”

Section: Datamentioning

confidence: 99%

An integration to optimally constrain the thermal structure of oceanic lithosphere

Goutorbe

Hillier

2013

JGR Solid Earth

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[1] The evolution through time of the oceanic lithosphere is a substantial, incompletely resolved geodynamical problem. Consensus remains elusive regarding its thermal structure, physical properties, and the best model through which to unify observational constraints. We robustly reevaluate all three of these by (i) simultaneously fitting heat flow, bathymetry, and temperatures derived from a shear velocity model of the upper mantle, (ii) using the three main thermal models (half-space, plate, and Chablis), and (iii) analyzing five depth-age curves, wherein contrasting techniques were used to exclude anomalous features from seafloor depths. The thermal models are updated to all include a temperature-dependent heat capacity, a temperature-and pressure-dependent thermal conductivity, and an initial condition of adiabatic decompression including melting. The half-space model, which lets the lithosphere thicken indefinitely, cannot accurately fit the subsidence curves and requires mantle potential temperatures, T m , that are too high. On the other hand, the models including a mechanism of basal heat supply are able to simultaneously explain all observations within two standard errors, with best-fitting parameters robust to the choice of the filtered bathymetry curve. For the plate model, which imposes a constant temperature at a fixed depth, T m varies within 1380-1390 C, the equilibrium plate thickness a within 106-110 km, and the bulk thermal expansivity a within 2.95À3.20 Á 10 À5 K À1 . For the Chablis model, which prescribes a fixed heat flow at the base of a thickening lithosphere, the best-fitting values are T m = 1320À1380 C, a = 176À268 km, a ¼ 3:05À3:60 Á 10 À5 K À1 . Driven by more accurate ocean depths, the plate model provides better joint-fittings to the observations; however, it requires values of a lower than experimentally measured, which can be explained by a reduction of the apparent expansivity due to elastic rigidity of the upper lithosphere. The Chablis model better fits the data when a is set close to or above the experimental values. Although statistically consistent within two standard errors, a tendency toward incompatibility between observed depth-age curves and seismically derived temperatures is revealed with new clarity, because the latter do not exhibit a clear steady state whereas the former flatten; further work is needed to identify the origin of this apparent discrepancy.This work opens the way to investigations fully independent of particular solutions of the heat equation.

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“…TdC is situated at the southwestern end of the Walvis Ridge‐Tristan / Gough hot spot track, 450 km east of the present‐day axis of the Mid‐Atlantic Ridge (MAR). Currently, different hypotheses exist to explain the geodynamic evolution of this island: The origin of TdC is either attributed to shallow plate tectonics (e.g., Anderson & Schramm, ) or to the existence of a mantle plume (e.g., Courtillot et al, ; Morgan, ; White & McKenzie, ). It has long been accepted that melts derived from a mantle plume directly beneath the island formed the archipelago (O'Connor & Duncan, ; Rohde et al, ).…”

Section: Introductionmentioning

confidence: 99%

Seismicity in the Vicinity of the Tristan Da Cunha Hot Spot: Particular Plate Tectonics and Mantle Plume Presence

et al. 2017

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Earthquake locations along the southern Mid‐Atlantic Ridge have large uncertainties due to the sparse distribution of permanent seismological stations in and around the South Atlantic Ocean. Most of the earthquakes are associated with plate tectonic processes related to the formation of new oceanic lithosphere, as they are located close to the ridge axis or in the immediate vicinity of transform faults. A local seismological network of ocean‐bottom seismometers and land stations on and around the archipelago of Tristan da Cunha allowed for the first time a local earthquake survey for 1 year. We relate intraplate seismicity within the African oceanic plate segment north of the island partly to extensional stresses induced by a bordering large transform fault and to the existence of the Tristan mantle plume. The temporal propagation of earthquakes within the segment reflects the prevailing stress field. The strong extensional stresses in addition with the plume weaken the lithosphere and might hint at an incipient ridge jump. An apparently aseismic zone coincides with the proposed location of the Tristan conduit in the upper mantle southwest of the islands. The margins of this zone describe the transition between the ductile and the surrounding brittle regime. Moreover, we observe seismicity close to the islands of Tristan da Cunha and nearby seamounts, which we relate to ongoing tectono‐magmatic activity.

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Global hotspot maps

Cited by 26 publications

References 44 publications

Multiple transition zone seismic discontinuities and low velocity layers below western United States

Multiple transition zone seismic discontinuities and low velocity layers below western United States

An integration to optimally constrain the thermal structure of oceanic lithosphere

Seismicity in the Vicinity of the Tristan Da Cunha Hot Spot: Particular Plate Tectonics and Mantle Plume Presence

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