Late Cretaceous foraminifera from Hikurangi Plateau, New Zealand

Abstract

Rock samples dredged from the Hikurangi Plateau, the large volcanic plateau currently being subducted beneath the North Island of New Zealand, at (1) 37°27.3′S, 178°0′W; (2) 37°22′S, 179°01′W; (3) 36°06′S, 178°22.5′W, include basalt, volcanic breccia and rare fossiliferous sediment. Late Cretaceous foraminifera occurring in two samples from a large volcanic feature at Site 1 provide the only pre-Miocene paleontological ages ever obtained from the plateau. Sites 2 and 3 proved non-fossiliferous. One of the Site 1 samples, a calcareous volcanic breccia, contains a dominantly planktic fauna with Heterohelix globulosa, H. cf. navarroensis, Globigerinelloides volutus and Rugoglobigerina rugosa, together with rare calcareous and agglutinated benthics. It is dated with high confidence as early-mid Campanian to mid-Maastrichtian, and more tentatively as mid-Maastrichtian, and is correlated with the Haumurian Stage in New Zealand. The second sample, studied only in thin section, contains an apparently nearly identical fauna, with undetermined species of Globigerinelloides, Heterohelix and Rugoglobigerina sp. Faunal similarity suggests that it is approximately the same age as the first sample. Both assemblages contain more than 95% planktic individuals, indicating a fully oceanic depositional site. Low faunal diversity (only 4 or perhaps 5 planktic taxa present) and lack of tropical or subtropical forms strongly suggest a relatively high paleolatitude for the site.