| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4722457 | Precambrian Research | 2015 | 24 Pages |
•Regional-scale, Grenvillian-aged deformation system along the southern margin of the North Australian Craton.•Deformation records late Mesoproterozoic amalgamation of the North and South Australian Cratons.•Deformation system is contiguous with the Musgrave Province to the south.
LA–ICP–MS U–Pb monazite and zircon geochronology from metapelites and migmatitic orthogneiss along the central southern margin of the North Australia Craton (NAC), central Australia, reveal the presence of a regional-scale Grenvillian-aged (ca. 1130 Ma) deformation system. Grenvillian-aged deformation extends over a strike length of over 110 km from the southern Aileron Province in the vicinity of Alice Springs to the Teapot Granite Complex within the Warumpi Province. There is also evidence for Grenvillian-aged migmatisation and resetting of monazite further west in the Mount Liebig area, which may extend the Grenvillian-aged footprint to a strike-length of at least 250 km. Deformation associated with Grenvillian-aged reworking produced map-scale east–west trending folds and strongly foliated, steeply dipping shear zones that define the structural architecture of the interface region between the Aileron and Warumpi Provinces. Shallow, westerly-plunging folds associated with partial melting have evolved into shear zones and mylonites that record south-side up movement. Phase equilibria modelling of age-constrained garnet–biotite ± sillimanite ± cordierite-bearing metapelites from the southern Aileron and Warumpi Provinces suggest Grenvillian-aged metamorphism reached temperatures in the range of 775–820 °C and pressures of 5–5.5 kbar, corresponding to thermal gradients of ∼130–165 °C kbar−1. The extensive Grenvillian-aged system reworks and overprints late Paleoproterozoic (ca. 1650–1630 Ma) high-grade metamorphic rocks. The Grenvillian-aged system occurs above a south dipping lithospheric-scale interface that has been geophysically imaged to depths of at least 200 km. This feature was interpreted to represent a fossil subduction zone of late Paleoproterozoic age. However, the presence of regional-scale Grenvillian-aged deformation in the crust above this feature suggests that it may instead be Grenvillian-aged. If that is the case, deformation along the southern margin of the NAC may record suturing of the NAC with the Grenvillian-aged Musgrave Province to the south. This would effectively place the long-lived, Late Mesoproterozoic ultrahot orogen that is the Musgrave Province in southern central Australia in an upper plate tectonic setting, linked to the convergence of the NAC with the South Australian Craton.
