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Australia: The Land Where Time Began |
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A Review of Wilson Cycle Plate Margins – Role in Continental Breakup
Along Sutures for Plumes
It is a fundamental concept in the Wilson Cycle theory that oceans close
and open along the former suture lines. J. Tuzo Wilson recognised that
marine palaeofaunas that were dissimilar, on both sides of the modern
Atlantic Ocean, were best explained by the existence of an earlier
proto-Atlantic Ocean. It is implied by the Wilson Cycle theory that
extensional deformation may be localised hundreds of million years after
the waning of collision by collision zones. In this study Buiter &
Torsvik review pairs of margins around the Atlantic Ocean and the Indian
Ocean to evaluate the extent to which former sutures were used in the
opening of oceans and to analyse the role of mantle plumes in the
breakup of continents. They used GPlates to aid in tectonic plate the
reconstructions.
It had been recognised by Wilson that the breakup associated with the
opening of the Atlantic Ocean did not always follow the line of previous
junction. The opening of the Atlantic, e.g., did not utilise the Iapetus
suture in the UK, breakup occurring along the younger Rheic suture north
of Florida, with breakup occurring along the older Pan-African
structures south of Florida. As with previous studies Buiter & Torsvik
found no correlation of the breakup age and the suture. Breakup often
occurs hundreds of millions of years after collision, though it may also
take more than a billion years, e.g., for the Australia-Antarctica and
Congo-São Francisco. Serious constraints are therefore placed on the
mechanisms of collision zone weakening.
It has been pointed out by a number of studies that there is a link
between the breakup of continents and mantle upwelling on a large scale.
There is much debate concerning whether existing rifts are used as
pathways by plumes, or whether an active role is played by plumes in the
initiation of the rifting. Also, it is important to realise that there
are several known cases where plume activity cannot be related to
breakup. Examples include Iberia-Newfoundland, Equatorial Atlantic
Ocean, and the Australia-Antarctica plate margins. Buiter & Torsvik
found a positive correlation between the age of breakup and Large
Igneous Province (LIP) age. It has been interpreted by Buiter & Torsvik
that plumes can aid the factual continental breakup. However, for
margins with a long history of rifting, such as Norway-Greenland, plumes
may be guided towards the rift where they trigger a continental breakup.
Buiter & Torsvik suggest this could offer a partial reconconciliation in
the active or passive role for mantle plumes debate.
(see Wilson, J.I., 1966. Did the Atlantic close and then reopen?
Nature 211, 676-681)
Buiter, S. J. H. and T. H. Torsvik (2014). "A review of Wilson Cycle
plate margins: A role for mantle plumes in continental break-up along
sutures?" Gondwana Research 26(2): 627-653.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |