AMINO-ACID GEOCHRONOLOGY OF PLEISTOCENE MARINE-SEDIMENTS IN THE WANGANUI BASIN - A NEW-ZEALAND FRAMEWORK FOR CORRELATION AND DATING

Amino acid analysis of indigenous protein preserved in fossil marine b ivalves from Plio-Pleistocene sediments in the Wanganui Basin, North I sland, New Zealand has provided an aminostratigraphy. D-alloisoleucine /L-isoleucine (D-alle/L-Ile) ratios were measured in the venerid marin e bivalves Tawera spissa and Austrovenus stutchburyi that show progres sively increasing D-alle/L-Ile ratios with increasing stratigraphical age. When calibrated by magnetostratigraphy, fission-track dating, rad iocarbon dating, and coccolith biostratigraphy, these relative D-alle/ L-Ile ages range up to c. 1 Ma. The aminostratigraphy provides a frame work of correlation and dating for other sites in the New Zealand area where other methods of dating are unavailable, as well as facilitatin g correlation with oxygen isotope stratigraphy. This is the first cali brated aminostratigraphical sequence from a long sequence of sediments that cover a significant proportion of the Pleistocene.