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| Titel |
Do Transform Faults Parallel Plate Motion? |
| VerfasserIn |
Richard Gordon, Jay Mishra |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097943
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| Publikation (Nr.) |
 EGU/EGU2014-13572.pdf |
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| Zusammenfassung |
| The rigid plate hypothesis implies that oceanic lithosphere does not contract horizontally as it
cools (hereinafter “no contraction”). An alternative hypothesis is that vertically averaged
tensional thermal stress in the competent lithosphere is fully relieved by horizontal thermal
contraction (hereinafter “full contraction”). These two hypotheses predict different azimuths
for transform faults, which we compare for azimuths of 140 globally distributed transform
faults. Differences are as large as 2.44°, but more typically are -¤1.0°. We determine the
sum-squared normalized misfit for various values of γ, which we define to be the fractional
multiple of the predicted difference in azimuth between full contraction and no
contraction. γ = 1 corresponds to full contraction, while γ = 0 corresponds to no
contraction. The sum-squared normalized misfit is minimized for γ = 0.9 ±0.4
(95% confidence limit). We conclude that significant horizontal thermal contraction
occurs in young oceanic lithosphere that displaces the walls of transform valleys
relative to the stable plate interior, which in turn causes a small but significant bias
in the azimuths of the transform faults. Thus plates are not rigid and transform
faults do not parallel plate motion, although these remain good approximations. |
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