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| Titel |
Phase change in subducted lithosphere, impulse, and quantizing Earth surface deformations |
| VerfasserIn |
C. O. Bowin, W. Yi, R. D. Rosson, S. T. Bolmer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 3 ; Nr. 6, no. 3 (2015-09-23), S.1075-1085 |
| Datensatznummer |
250115514
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| Publikation (Nr.) |
 copernicus.org/se-6-1075-2015.pdf |
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| Zusammenfassung |
| The new paradigm of plate tectonics began in 1960 with Harry H. Hess's 1960
realization that new ocean floor was being created today and is not everywhere
of Precambrian age as previously thought. In the following decades an
unprecedented coming together of bathymetric, topographic, magnetic,
gravity, seismicity, seismic profiling data occurred, all supporting and
building upon the concept of plate tectonics. Most investigators accepted
the premise that there was no net torque amongst the plates. Bowin (2010)
demonstrated that plates accelerated and decelerated at rates 10−8
times smaller than plate velocities, and that globally angular momentum is
conserved by plate tectonic motions, but few appeared to note its existence.
Here we first summarize how we separate where different mass sources may lie
within the Earth and how we can estimate their mass. The Earth's greatest
mass anomalies arise from topography of the boundary between the metallic
nickel–iron core and the silicate mantle that dominate the Earth's spherical
harmonic degree 2 and 3 potential field coefficients, and overwhelm all
other internal mass anomalies. The mass anomalies due to phase changes in
olivine and pyroxene in subducted lithosphere are hidden within the
spherical harmonic degree 4–10 packet, and are an order of magnitude smaller
than those from the core–mantle boundary. Then we explore the geometry of
the Emperor and Hawaiian seamount chains and the 60° bend between them
that aids in documenting the slow acceleration during both the Pacific
Plate's northward motion that formed the Emperor seamount chain and its westward
motion that formed the Hawaiian seamount chain, but it decelerated at the time of
the bend (46 Myr). Although the 60° change in direction of the Pacific
Plate at of the bend, there appears to have been nary a pause in a passive
spreading history for the North Atlantic Plate, for example. This, too,
supports phase change being the single driver for plate tectonics and
conservation of angular momentum. Since mountain building we now know
results from changes in momentum, we have calculated an experimental
deformation index value (1–1000) based on a world topographic grid at 5 arcmin spacing and displayed those results for viewing. |
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