STRUCTURE OF THE BROOME HEAD METAMORPHICS AND RELATED ROCKS IN THE SHOALWATER BAY AREA, NORTHERN NEW-ENGLAND FOLD BELT

Medium-to high-grade metamorphic rocks of the Palaeozoic Shoalwater te rrane, forming part of the accretionary prism of the New England Fold Belt, crop out at Shoalwater Bay, Queensland. Two formations, the Shoa lwater and Townshend Formations, have undergone complex multiple defor mation during the Late Permian to Triassic Hunter-Bowen Orogeny. Most generations of structures are correlated from schist on Townshend isla nd to migmatitic gneiss of the Broome Head Metamorphics on the western shore of Shoalwater Bay. Early accretionary structures (D-1) have bee n obliterated by later deformations D-2 to D-6. D-2 produced tight fol ds and a metamorphic layering. S-2 which is the form surface for many folds. Dg resulted in tight to isoclinal folds which transposed S-2 in to an S-3 layering, such that S-2/S-3 is the form surface for later fo lds in much of the Broome Head Metamorphics. D-3 has formed map-scale and outcrop-scale folds on Townshend Island and abundant mesoscale fol ds in the Broome Head Metamorphics. D-5 folds are open, trend east and have kilometre-scale wavelengths. D-6 folds occur only in the Broome Head Metamorphics, are upright and north-trending, and post-date the f ault emplacement of the metamorphics against low-grade rocks to the we st. These structures are interpreted as forming during a collisional e vent which caused the Hunter-Bowen Orogeny.