Last Ice Age Millennial Scale Climate Changes Recorded in Huon Peninsula Corals

• Main Authors: Yokoyama, Yusuke, Esat, Tezer, Fifield, L Keith, Lambeck, Kurt
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: University of Arizona
• Subjects: Keywords: carbon 14; coral; ice; sea water; uranium; paleoclimate; radiocarbon dating; uranium series dating; age determination; article; atmospheric diffusion; calibration; nonhuman; Papua New Guinea; sea; Huon; North Atlantic; North atlantic Thermohaline circulation
• Online Access: http://hdl.handle.net/1885/90885

Uranium series and radiocarbon ages were measured in corals from the uplifted coral terraces of Huon Peninsula (HP), Papua New Guinea, to provide a calibration for the 14C time scale beyond 30 ka (kilo annum). Improved analytical procedures, and quantitative criteria for sample selection, helped discriminate diagenetically altered samples. The base-line of the calibration curve follows the trend of increasing divergence from calendar ages, as established by previous studies. Superimposed on this trend, four well-defined peaks of excess atmospheric radiocarbon were found ranging in magnitude from 100% to 700%, relative to current levels. They are related to episodes of sea-level rise and reef growth at HP. These peaks appear to be synchronous with Heinrich Events and concentrations of ice-rafted debris found in North Atlantic deep-sea cores. Relative timing of sea-level rise and atmospheric 14C excess imply the following sequence of events: An initial sea-level high is followed by a large increase in atmospheric 14C as the sea-level subsides. Over about 1800 years, the atmospheric radiocarbon drops to below present ambient levels. This cycle bears a close resemblance to ice-calving episodes of Dansgaard-Oeschger and Bond cycles and the slow-down or complete interruption of the North Atlantic thermohaline circulation. The increases in the atmospheric 14C levels are attributed to the cessation of the North Atlantic circulation.