An alternative astronomical calibration of the lower Pleistocene timescale based on ODP Site 677

TLDR

Ocean Drilling Program Site 677 provides high‑resolution stable‑isotope records of benthic and planktonic foraminifera spanning the Pleistocene and upper Pliocene. The isotope record from Site 677 aligns with SPECMAP and DSDP 607 but matches orbital models better when the timescale is adjusted below Stage 16, indicating that key magnetic reversal dates are 5–7 % younger than current radiometric estimates.

Abstract

ABSTRACT Ocean Drilling Program (ODP) Site 677 provided excellent material for high resolution stable isotope analysis of both benthonic and planktonic foraminifera through the entire Pleistocene and upper Pliocene. The oxygen isotope record is readily correlated with the SPECMAP stack (Imbrie et al. 1984) and with the record from DSDP 607 (Ruddiman et al. 1986) but a significantly better match with orbital models is obtained by departing from the timescale proposed by these authors below Stage 16 (620 000 years). It is the stronger contribution from the precession signal in the record from ODP Site 677 that provides the basis for the revised timescale. Our proposed modification to the timescale would imply that the currently adopted radiometric dates for the Matuyama–Brunhes boundary, the Jaramillo and Olduvai Subchrons and the Gauss–Matuyama boundary underestimate their true astronomical ages by between 5 and 7%.