The major crustal boundaries of Australia in 2D and 3D: implications for metallogenesis

Date & time

5.30–6.15pm 17 October 2017

Location

Jaeger 1 Seminar Room, RSES

Speakers

Dr. Michael Doublier

Event series

Contacts

 Patrick Carr

By Doublier, M.D., Korsch, R.J., Brennan, T., Champion, D.C., Czarnota, K., Huston, D.L., Nicoll, M.G.

Abstract

For over 35 years, deep seismic reflection profiles have been acquired across Australia [1] to better understand the crustal architecture and geodynamic evolution of key geological provinces, basins and resources. Major crustal-scale breaks have been interpreted in many of the profiles, and are often inferred to represent relict sutures between different crustal blocks. The widespread coverage of seismic profiles has allowed construction of the ‘Major Crustal Boundaries of Australia’ dataset by using geological (e.g. outcrop mapping, drillhole, geochronology, isotope) and geophysical (e.g. gravity, aeromagnetic, magnetotelluric) data to map the plan form distribution of crustal boundaries away from the seismic profiles [2].

Here we present the first continental-scale 3D model of the ‘Major Crustal Boundaries of Australia’ [3]. This model is constructed from the 2D linework in map view [2], with the third (depth) dimension constrained using the geometry of the boundaries interpreted in deep seismic reflection profiles, and then interpolated away from the profiles. The implementation of the third dimension (depth) has led to improvement of the 2D linework by identifying areas of inconsistency, e.g. with regards to cross-cutting relationships in the third dimension. Both the 2D and 3D datasets allow for a better understanding of the evolution and amalgamation of the Australian continent through time, from the Mesoarchean to the Cenozoic. They also provide a powerful reference frame for integrated studies focused on crustal and lithospheric architecture utilising datasets such as isotopic maps (e.g. Sm-Nd [4]) and seismic velocity models (e.g. P- and S-wave velocity [5]). This is illustrated by the example of the Archean Yilgarn Craton, where various geophysical, geochemical, geological and geochronological datasets have matured over the last decade to the point that craton-scale investigations are now possible. Integration of these data sets with the 3D crustal boundaries shows that the latter provide additional important constraints for models of the crustal development of the Yilgarn Craton, and also for explaining the localisation of mineralisation.

References:

[1] Kennett BLN et al. (2013) ANU Press and Geoscience Australia, Canberra, 180 pp.

[2] Korsch RJ and Doublier MP (2016) Ore Geology Reviews (DOI:10.1016/j.oregeorev.2015.05.010)

[3] Doublier MP et al. (2016) 3D Model of the Major Crustal Boundaries of Australia [Digital Dataset]. Geoscience Australia, Commonwealth of Australia, Canberra. http://www.ga.gov.au/metadata-gateway/metadata/record/101466/

[4] Champion DC (2013) Geoscience Australia Record 2013/044

[5] Kennet BLN and Salmon M (2012) Australian Journal of Earth Sciences 59: 2091-1103

Bio:

After a Master in structural geology at the University of Giessen. Michael did a PhD at University of Frankfurt, working on the Montagne Noire Gneiss Dome and surrounding sediments in Southern France, combining structural geology with low-grade petrology and K-Ar geochronology. In 2007 he joined the Geological Survey of Western Australia, working on the regional geology of the eastern and central Yilgarn Craton. In July 2013 he joined the Mineral Systems Branch at Geoscience Australia working broadly in the areas of structural geology and tectonics.

 

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