Old radiocarbon ages in the southwest Pacific Ocean during the last glacial period and deglaciation
journal contribution
posted on 2023-05-16, 12:12authored bySikes, EL, Catherine Samson, Guilderson, TP, Howard, W
Marine radiocarbon (14C) dates are widely used for dating oceanic events and as tracers of ocean circulation, essential components for understanding ocean-climate interactions. Past ocean ventilation rates have been determined by the difference between radiocarbon ages of deep-water and surface-water reservoirs, but the apparent age of surface waters (currently ~400 years in the tropics and ~1,200 years in Antarctic waters) might not be constant through time, as has been assumed in radiocarbon chronologies and palaeoclimate studies. Here we present independent estimates of surface-water and deep-water reservoir ages in the New Zealand region since the last glacial period, using volcanic ejecta (tephras) deposited in both marine and terrestrial sediments as stratigraphic markers. Compared to present-day values, surface-reservoir ages from 11,900 14C years ago were twice as large (800 years) and during glacial times were five times as large (2,000 years), contradicting the assumption of constant surface age. Furthermore, the ages of glacial deepwater reservoirs were much older (3,000-5,000 years). The increase in surface-to-deep water age differences in the glacial Southern Ocean suggests that there was decreased ocean ventilation during this period.
History
Publication title
Nature
Volume
405
Issue
6786
Pagination
555-559
ISSN
0028-0836
Department/School
Institute for Marine and Antarctic Studies
Publisher
MacMillan Publishers Ltd
Place of publication
London
Repository Status
Restricted
Socio-economic Objectives
Other environmental management not elsewhere classified