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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., R├ęgnier 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