Open AccessPlate dynamics: Caribbean map corrections and hotspot push
Author(s) -
Harper J. F.
Publication year - 1990
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1990.tb00695.x
Subject(s) - subduction , geology , hotspot (geology) , slab , lithosphere , mid ocean ridge , mantle (geology) , plate tectonics , seismology , slab window , drag , shear zone , geometry , geodesy , oceanic crust , mechanics , geophysics , physics , mathematics , tectonics
SUMMARY In 1986 the author's previous paper describing a simple mathematical model for the forces driving the plates had an rms error of 1.62 per cent in its best case. The model included slab pull and its global and local reactions proportional to speed times (age) 3/2 , viscous drag due to shear under moving plates and in the flow towards mantle sinks at midocean ridges and sources at subduction zones, ridge push proportional to plate age, and friction at continental collision zones. Strengths of the various forces were found by least‐squares fitting. Three different improvements now reduce the error to 1.14 per cent. They are (1) revision of the N–S American plate boundary east of the Caribbean sea to run along the 15°20′ fracture zone, (ii) removal of a transform segment from the Caribbean subduction zone, and (iii) allowing for ‘hotspot push’. Hotspots cause upward flow in the mantle, which spreads outwards under the lithosphere above, and pushes two plates apart if their boundary runs nearby, in a way which is calculated. The results and their statistical significance are estimated by a method given by Backus, Park & Garbasz (1981), modified slightly because three of the equations in the model are linearly dependent on the remainder. All the physical mechanisms envisaged in this work as driving plates turn out to be significant except local reaction to slab pull, the effect of which is very small anyway.