Superposed folding in the rockley district, lachlan fold belt, New South Wales

Low grade metasediments and metavolcanics of the Hill End Synclinorial Zone within the Rockley district, NSW have experienced two phases of macroscopic folding (D₁and D₂), both of which are post-latest Silurian in age. No hiatus is evident between D₁and D₂. D1 produced large Fi folds (λ/2 usually > 2 km) lacking mesoscopic elements and having variable axial trends. D₂was associated with the development of regional slaty cleavage (S₂) and mesoscopic folds which are parasitic on plunging macroscopic F₂folds (λ/2=0.4-2 km). D₂strain is variable, being most intense in the north of the district where slaty cleavage and tight mesoscopic F₂folds are well developed, and weakest in the south where mesoscopic folds are absent or usually gentle and cleavage is often feebly developed even in mica-rich rocks, which are stratigraphic equivalents to slates and schists in the north. The F₁fold mechanism may involve multiple folding, simultaneous folding in more than one direction, or complex buckling of layers of variable thickness. D₁and D₂are tentatively correlated with folding events elsewhere in the Hill End Synclinorial Zone.