A High-Resolution Radiocarbon Calibration Between 11,700 and 12,400 Calendar Years Bp Derived from ²³⁰Th Ages of Corals from Espiritu Santo Island, Vanuatu

Abstract

This paper presents radiocarbon results from a single Diploastrea heliopora coral from Vanuatu that lived during the Younger Dryas climatic episode, between ca. 11,700 and 12,400 calendar yr bp. The specimen has been independently dated with multiple 230Th measurements to permit calibration of the 14C time scale. Growth bands in the coral were used to identify individual years of growth. 14C measurements were made on each year. These values were averaged to achieve decadal resolution for the 14C calibration. The relative uncertainty of the decadal 14C data was below 1% (2σ). The data are in good agreement with the existing dendrochronology and allow for high-resolution calibration for most years. Variations in the fine structure of the 14C time series preserved in this specimen demonstrate sporadic rapid increases in the Δ14C content of the surface ocean and atmosphere. Certain sharp rises in Δ14C are coincident with gaps in coral growth evidenced by several hiatuses. These may be related to rapid climatic changes that occurred during the Younger Dryas. This is the first coral calibration with decadal resolution and the only such data set to extend beyond the dendrochronology-based 14C calibration.

Paired 14C and 230Th/U Dating of Surface Corals from the Marquesas and Vanuatu (Sub-Equatorial Pacific) in the 3000 to 15,000 Cal Yr Interval

“…Between 3000 cal yr and 11,500 cal yr, the 14 C ages are very reproducible within each coral (Table 1). Using an R value of 400 yr, the estimates of the difference between the absolute and 14 C ages are in agreement with previous determinations (Stuiver et al 1998;Burr et al 1998;Edwards et al 1993;Bard et al 1993Bard et al , 1998 (Figures 2, 5, 6). Beyond 11,500 cal yr, 2 corals dated at 12,000 and 15,100 cal yr, however, present scattered 14 C values.…”

INTCAL98 Radiocarbon Age Calibration, 24,000–0 cal BP

“…For the 11,800-8300 cal BP interval, the Bard et al (1998), Burr et al (1998), and Edwards et al (1993) coral data yield tree-ring-coral offsets of, respectively, 298 ± 3314C yr (11,590-8450 cal BP,1 number of comparisons n =19), 537 ± 3814C yr (1.1,770-11730 cal BP, n = 5) and 587 ± 29 (11,045-j 8363 cal BP, n =10). Omitting one outlier from the Edwards et al data reduces the 587 ± 2914C yrj to 502 ± 3314C r. Without the outlier, the weighted average offset for all samples is 440±21 '4C yr. ` Differences between oceans are relatively small: R is 406 ± 65 14C yr (11,590-8450 cal BP, n = 6) for the Atlantic Ocean and 440 ± 2014C yr (11,770-8363 cal BP, n = 27) for the Pacific (one outlier omitted).…”

“…Southern Hemisphere offset measurements (Bard et al 1994;Bard 1988;Edwards et al 1993;Burr et al 1998 with 35 pre-bomb samples yielding 494 ± 10 yr for Vanuatu).…”

“…Uranium-thorium (U-Th) dating of corals extends the cal age range (Bard et al 1998;Burr et al 1998;Edwards et al 1993). Whereas tree-ring 14C, via the photosynthetic cycle, equilibrates with atmospheric carbon dioxide, corals equilibrate with mixed-layer ocean bicarbonate.…”

Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals

“…We report 4 new pre-bomb records from the 1940s and 1950s and compare these to existing records published in the literature. We then examine a published South Pacific paleocoral record from the Younger Dryas (Burr et al 1998) to constrain both the reservoir age at that time, and the rate at which it changed between ~11.8 and 12.3 kyr BP. This paper is restricted to coral results.…”