In:
Radiocarbon, Cambridge University Press (CUP), Vol. 42, No. 3 ( 2000), p. 383-401
Abstract:
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 14 C 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 14 C excess imply the following sequence of events: An initial sea-level high is followed by a large increase in atmospheric 14 C 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 14 C levels are attributed to the cessation of the North Atlantic circulation.
Type of Medium:
Online Resource
ISSN:
0033-8222
,
1945-5755
DOI:
10.1017/S0033822200030320
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2000
detail.hit.zdb_id:
2028560-7
SSG:
11
SSG:
13
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