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Hotspots: The First 25 Years. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm043p0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Richards MA, Hager BH. Effects of lateral viscosity variations on long-wavelength geoid anomalies and topography. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib08p10299] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ricard Y, Richards M, Lithgow-Bertelloni C, Le Stunff Y. A geodynamic model of mantle density heterogeneity. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02216] [Citation(s) in RCA: 382] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McNutt M. Implications of regional gravity for state of stress in the Earth's crust and upper mantle. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb085ib11p06377] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Vogt PR, Zondek B, Fell PW, Cherkis NZ, Perry RK. Seasat altimetry, the North Atlantic geoid, and evaluation by shipborne subsatellite profiles. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb089ib12p09885] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Alvarez W. Geological evidence for the geographical pattern of mantle return flow and the driving mechanism of plate tectonics. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb087ib08p06697] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Williams Q, Revenaugh J, Garnero E. A correlation between ultra-Low basal velocities in the mantle and hot spots. Science 1998; 281:546-9. [PMID: 9677194 DOI: 10.1126/science.281.5376.546] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The statistical correlation between the locations of hot spots at the surface of Earth and the distribution of ultra-low-velocity zones at the base of the mantle has about a 1 percent chance of arising randomly. This correlation is more significant than that between hot spots and negative velocity anomalies in tomographic models of deep mantle compressional and shear velocity. This correlation is consistent with the notion that many hot spots originate in a low-velocity, probably partially molten layer at the core-mantle boundary and undergo little lateral deflection on ascent.
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Affiliation(s)
- Q Williams
- Department of Earth Sciences and Institute of Tectonics, University of California, Santa Cruz, CA 95064, USA
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Long-wavelength variations in Earth’s geoid: physical models and dynamical implications. ACTA ACUST UNITED AC 1997. [DOI: 10.1098/rsta.1989.0038] [Citation(s) in RCA: 376] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The seismic velocity anomalies resolved by seismic tomography are associated with variations in density that lead to convective flow and to dynamically maintained topography at the Earth’s surface, the core-mantle boundary (CMB), and any interior chemical boundaries that might exist. The dynamic topography resulting from a given density field is very sensitive to viscosity structure and to chemical stratification. The mass anomalies resulting from dynamic topography have a major effect on the geoid, which places strong constraints on mantle structure. Almost 90% of the observed geoid can be explained by density anomalies inferred from tomography and a model of subducted slabs, along with the resulting dynamic topography predicted for an Earth model with a low-viscosity asthenosphere (
ca
. 10
20
Pa s) overlying a moderate viscosity (
ca
. 10
22.5
Pa s) lower mantle. This viscosity stratification would lead to rapid mixing in the asthenosphere, with little mixing in the lower mantle. Chemically stratified models can also explain the geoid, but they predict hundreds of kilometres of dynamic topography at the 670 km discontinuity, a prediction currently unsupported by observation. A low-viscosity or chemically distinct D" layer tends to decouple CMB topography from convective circulation in the overlying mantle. Dynamic topography at the surface should result in long-term changes in eustatic sea level.
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Pari G, Peltier WR. The free-air gravity constraint on subcontinental mantle dynamics. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb02099] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
A finite-element formulation of faults has been incorporated into time-dependent models of mantle convection with realistic rheology, continents, and phase changes. Realistic tectonic plates naturally form with self-consistent coupling between plate and mantle dynamics. After the initiation of subduction, trenches rapidly roll back with subducted slabs temporarily laid out along the base of the transition zone. After the slabs have penetrated into the lower mantle, the velocity of trench migration decreases markedly. The inhibition of slab penetration into the lower mantle by the 670-kilometer phase change is greatly reduced in these models as compared to models without tectonic plates.
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Crumpler LS, Head JW, Aubele JC. Relation of Major Volcanic Center Concentration on Venus to Global Tectonic Patterns. Science 1993; 261:591-5. [PMID: 17758169 DOI: 10.1126/science.261.5121.591] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Global analysis of NASA Magellan image data indicates that a major concentration of volcanic centers covering approximately 40 percent of the surface of Venus occurs between the Beta, Atla, and Themis regiones. Associated with this enhanced concentration are geological characteristics commonly interpreted as rifting and mantle upwelling. Interconnected low plains in an annulus around this concentration are characterized by crustal shortening and infrequent volcanic centers that may represent sites of mantle return flow and net down-welling. Together, these observations suggest the existence of relatively simple, largescale patterns of mantle circulation similar to those associated with concentrations of intraplate volcanism on Earth.
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Cazenave A, Souriau A, Dominh K. Global coupling of Earth surface topography with hotspots, geoid and mantle heterogeneities. Nature 1989. [DOI: 10.1038/340054a0] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bercovici D, Schubert G, Glatzmaier GA. Three-Dimensional Spherical Models of Convection in the Earth's Mantle. Science 1989; 244:950-5. [PMID: 17731881 DOI: 10.1126/science.244.4907.950] [Citation(s) in RCA: 158] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Three-dimensional, spherical models of mantle convection in the earth reveal that upwelling cylindrical plumes and downwelling planar sheets are the primary features of mantle circulation. Thus, subduction zones and descending sheetlike slabs in the mantle are fundamental characteristics of thermal convection in a spherical shell and are not merely the consequences of the rigidity of the slabs, which are cooler than the surrounding mantle. Cylindrical mantle plumes that cause hotspots such as Hawaii are probably the only form of active upwelling and are therefore not just secondary convective currents separate from the large-scale mantle circulation. Active sheetlike upwellings that could be associated with mid-ocean ridges did not develop in the model simulations, a result that is in agreement with evidence suggesting that ridges are passive phenomena resulting from the tearing of surface plates by the pull of descending slabs.
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Richards MA, Hager BH, Sleep NH. Dynamically supported geoid highs over hotspots: Observation and theory. ACTA ACUST UNITED AC 1988. [DOI: 10.1029/jb093ib07p07690] [Citation(s) in RCA: 194] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Jung WY, Rabinowitz PD. Residual geoid anomalies of the North Atlantic Ocean and their tectonic implications. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/jb091ib10p10383] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Cazenave A, Dominh K, Allegre CJ, Marsh JG. Global relationship between oceanic geoid and topography. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/jb091ib11p11439] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pavoni N. Die pazifisch-antipazifische Bipolarität im Strukturbild der Erde und ihre geodynamische Deutung. ACTA ACUST UNITED AC 1985. [DOI: 10.1007/bf01824896] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Trench depth: Variation and significance. ACTA ACUST UNITED AC 1983. [DOI: 10.1029/gd011p0075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
The study of oceanic crust continues to be important because of the presence of economic resources in oceanic areas and because many fundamental problems of geologic evolution are best solved from studies of the ocean. Although modeling and syntheses of existing data remain important, key breakthroughs in the future will come from the application of new technology such as multichannel towed seismic arrays, deep-towed side scan sonars, improved thermal probes, deep drilling, and satellite altimeters.
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