Superposed folding in the Rockley district, Lachlan Fold Belt, New South Wales

Abstract

Low grade metasediments and metavolcanics of the Hill End Synclinorial Zone within the Rockley district, NSW have experienced two phases of macroscopic folding (D1 and D2), both of which are post‐latest Silurian in age. No hiatus is evident between D1 and D2. D1 produced large Fi folds (λ/2 usually > 2 km) lacking mesoscopic elements and having variable axial trends. D2 was associated with the development of regional slaty cleavage (S2) and mesoscopic folds which are parasitic on plunging macroscopic F2 folds (λ/2=0.4–2 km). D2 strain is variable, being most intense in the north of the district where slaty cleavage and tight mesoscopic F2 folds 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 F1 fold mechanism may involve multiple folding, simultaneous folding in more than one direction, or complex buckling of layers of ...