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Mineralisation
Marie-Aude Bonnardot, Gordon Lister, Joe Kurtz and
Marnie Forster
Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
Tectonic plate boundaries are the preferred location for economic mineralization,
which appear to have been emplaced at specific time. This two-folded
project proposes to re-examine tectonic evolution of the lithosphere
along convergent and divergent boundaries. This project involves the
development and application of the tectonic reconstruction tool, Pplates,
in collaboration with Joe Kurtz and is also undertaken with the support
from the DeBeers group.
Along convergent margins, subduction of lithospheric anomalies like
seamount chain or oceanic plateau has the potential to vastly impact
on the motion of tectonic plates. A famous example is the collision of
the Ontong Java oceanic plateau along the New Guinea subduction zone
to the north of Australia, which induced a drastic plate reorganisation
involving subduction reversal in the SW Pacific. Based on previous works
(Bonnardot et al., 2008), the first part of the project focuses on understanding
the 3D geometry of slabs related to seafloor heterogeneities subduction
and in particular, it focuses on the identification of slab tears, which
may have a fundamental effect on the upper plate tectonic regime and
on the porphyry deposits emplacement. We are currently revising the slab
geometry in the Tonga, Sumatra and the South America subduction zones
in regards to the tectonic evolution of the overriding plate, based on
the analyse of the seismicity distribution and the stress regime within
the involved lithospheric plates.
The second part of that project focuses on intracontinental
rifting processes and aims at understanding the tectono-magmatic structures
associated with anorogenic alkaline trends, for instance the relationship
between transform faults/structural pattern of the mid-oceanic ridge
and kimberlite emplacement.
Outcomes will allow refining plate motion in global tectonic reconstruction,
as it will result in better quantifying the intraplate deformation that
occurs during rifting initiation.
Bonnardot M.-A., Régnier M., Christova C., Ruellan E., Tric E. 2008.
Seismological evidence
for a slab detachment in the Tonga subduction zone. Tectonophysics, doi:10.1016/j.tecto.2008.10.01