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Detailed Reference Information |
Karsten, J.L. and Delaney, J.R. (1989). Hot spot–ridge crest convergence in the northeast Pacific. Journal of Geophysical Research 94. doi: 10.1029/88JB03229. issn: 0148-0227. |
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Evolution of the Juan de Fuca Ridge during the past 7 m.y. has been reconstructed taking into account both the propagating rift history and migration of the spreading center in the ''absolute'' (fixed hot spot) reference frame. Northwestward migration of the spreading center (at a rate of 30 km/m.y.) has resulted in progressive encroachment of the ridge axis on the Cobb Hot Spot and westward jumping of the central third of the ridge axis more recently than 0.5 Ma. Seamounts in the Cobb-Eickelberg chain are predicted to display systematic variations in morphology and petrology, and a reduction in the age contrast between the edifice and underlying crust, as a result of the ridge axis approach. Relative seamount volumes also indicate that magmatic output of the hot spot varied during this interval, with a reduction in activity between 2.5 and 4.5 Ma, compared with relatively more robust activity before and after this period. Spatial relationships determined in this reconstruction allow hypotheses relating hot spot activity and rift propagation to be evaluated. In most cases, rift propagation has been directed away from the hot spot during the time period considered. Individual propagators show some reduction in propagation rate as separation between the propagating rift tip and hot spot relationship. No obvious correlation exists between propagation rate and increasing proximity of the hot spot to the ridge axis or increasing hot spot output. Taken together, these observations do not offer compelling support for the concept of hot spot driven rift propagation. However, short-term reversals in propagation direction at the Cobb Offset coincide with activity of the Heckle melting anomaly, suggesting that local propagation effects may be related to excess magma supply at the ridge axis. ¿ American Geophysical Union 1989 |
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Abstract |
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Keywords
Tectonophysics, Plate boundary—general, Marine Geology and Geophysics, Midocean ridge processes, Marine Geology and Geophysics, Plate tectonics, Information Related to Geographic Region, Pacific Ocean |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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