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The Malpelo Plate Hypothesis and implications for nonclosure of the Cocos‐Nazca‐Pacific plate motion circuit

2017; American Geophysical Union; Volume: 44; Issue: 16 Linguagem: Inglês

10.1002/2017gl073704

1944-8007

Tuo Zhang, Richard G. Gordon, J. K. Mishra, Chengzu Wang,

High-pressure geophysics and materials

Abstract Using global multiresolution topography, we estimate new transform‐fault azimuths along the Cocos‐Nazca plate boundary and show that the direction of relative plate motion is 3.3° ± 1.8° (95% confidence limits) clockwise of prior estimates. The new direction of Cocos‐Nazca plate motion is, moreover, 4.9° ± 2.7° (95% confidence limits) clockwise of the azimuth of the Panama transform fault. We infer that the plate east of the Panama transform fault is not the Nazca plate but instead is a microplate that we term the Malpelo plate. With the improved transform‐fault data, the nonclosure of the Nazca‐Cocos‐Pacific plate motion circuit is reduced from 15.0 mm a −1 ± 3.8 mm a −1 to 11.6 mm a −1 ± 3.8 mm a −1 (95% confidence limits). The nonclosure seems too large to be due entirely to horizontal thermal contraction of oceanic lithosphere and suggests that one or more additional plate boundaries remain to be discovered.