Bernhard Sporli

Geology of the red rocks — turbidite association, Wellington peninsula, New Zealand

Abstract The Wellington peninsula is composed of Torlesse terrane greywacke turbidites with intercalations of red rocks that occur in various combinations of metabasalt, chert, and coloured (red, green, grey) argillite. The red rocks define 2 km-scale folds (the Rimurapa inverted syncline and Evans Bay Syncline) in the Wellington peninsula. The best known example of red rocks crops out at a point called Red Rocks on the coast about 8 km south of Wellington City. Radiolarians in cherts at Red Rocks indicate a Late Permian age, whereas radiolarians from phosphorite and a probable hydrozoan fossil (Heterastridium) in grey argillite of the turbidite sequence indicate a Late Triassic (Carnian-Norian) age. Radiolarians from phosphatic concretions in grey argillite interbedded with turbidites elsewhere in the Wellington peninsula also indicate a Late Triassic age. The fossil ages indicate a 40–50 Ma age difference between the red rocks and the enclosing turbidites. In addition to their older age, the red rocks: ...