Ages between 1000 and 1200 Ma have been recorded from diverse rock types at 10 scattered localities outside the Musgrave Block and Ammaroodinna Inlier. All are K-Ar and Rb-Sr mineral concentrates or whole rock ages, except 1 U-Pb age on detrital zircons from the Bunyeroo Formation, Wearing Hills. Samples outside the Musgrave Block which exhibit solely thermal updating are found in the Peake and Denison Inliers, Mount Painter Inliers, Willyama Inliers and the Stuart Shelf. This thermal event is apparently synchronous with emplacement of the Gairdner Dyke Swarm and extrusion of the Beda Volcanics. All 3 are apparently synchronous and manifestations of a major phase of crustal extension - best dated at 1070 +/- 74 Ma. This report collates and interprets data in terms of more widespread effects of the Musgravian Orogeny and thermal resetting during a subsequent period of crustal extension.