Partial convective overturn of Archaean crust in the east Pilbara Craton, Western Australia: driving mechanisms and tectonic implications

Strain varies systematically from weakly-developed, outward-dipping: S-tectonites in the similar to 3320-3310 +/- 10 Ma Mount Edgar Batholith to intensely deformed, subvertical, L-tectonites in greenstones of the Warrawoona syncline. A consistent 'greenstone-down/batholith-up' sense of shear is recorded in batholithic domal margins and adjacent high-grade supracrustal rims: lineations converge to a central zone of subvertical extension (zone of sinking) along the synclinal axis. AT domal margins, early kinematic granitoid sheets and 'intrusive diatexites' are subconcordant to a well-developed, dome-parallel schistosity, but late- to post kinematic intrusives are discordant, high-level plutons. All granitoids are the same age, within analytical error.