PLEISTOCENE UNCONFORMITY-BOUNDED SHELF SEQUENCES (WANGANUI BASIN, NEW-ZEALAND) CORRELATED WITH GLOBAL ISOTOPE RECORD

Eleven successive unconformity-bound sequences in the Castlecliff section (Wanganui Basin), each typically composed of a lower, variably conglomeratic, 0.1-2 m thick shell bed and an upper 5-20 m thick barren siltstone, are identified in the stratotype of the local (New Zealand) middle Pleistocene Castlecliffian Stage. Based on magnetostratigraphy, the section is correlated with the published benthonic oxygen isotope curve for DSDP core 552A from the North Atlantic. Each of the sequences accumulated during one of the odd-numbered interglacial isotope stages in the interval 31 to 11, inclusive; the unconformities developed during intervening glacial ages when the shelf was exposed through glacio-eustatic lowering. The correlation provides a geochronologic framework for assessment of the eustatic contribution to the generation of the sequences in a situation where the paleoshorelines and related shelf sequences are preserved, and for which an independent approximation of the sea-level history is available in the form of an oxygen isotope curve. © 1990.