Late Triassic Radiolaria from the Torlesse Terrane, Rimutaka Range, North Island, New Zealand

Abstract

Red cherts from the Torlesse basement near the Rimutaka Summit have yielded radiolarians of Late Triassic (late Early to late Middle Norian) age, and date an ocean‐fioor sequence involved in an imbricated accretionary prism. The fauna is similar to faunas collected from terrigenous assemblages on Kapiti Island to the west. The similarity of faunas from ocean‐floor and terrigenous sequences in this part of the Torlesse indicates a difference to the Waipapa Terrane, where Tethyan (low latitude) faunas in the ocean‐floor sequences contrast with a non‐Tethyan (high latitude) fauna in the terrigenous sequences. The Rimutaka fossils also show that two separate but geographically superposed patterns of eastward younging fossil ages can be mapped for this part of the Torlesse Terrane: one for the ocean‐floor sequences and one for the terrigenous sequences.

Keywords:

• micropaleontology
• radiolarians
• cherts
• greywackes
• seafloor
• subduction
• accretion
• paleogeography