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RADIOCARBON, Vol 44, Nr 2, 2002, p 567580 2002 by the Arizona Board of Regents on behalf of the University of Arizona RADIOCARBON DATING OF DEEP-SEA CORALS

Summary: RADIOCARBON, Vol 44, Nr 2, 2002, p 567580 2002 by the Arizona Board of Regents on behalf of the University of Arizona
Jess F Adkins1 Shelia Griffin2 Michaele Kashgarian3 Hai Cheng4 E R M Druffel2
E A Boyle5 R Lawrence Edwards4 Chuan-Chou Shen4
ABSTRACT. Deep-sea corals are a promising new archive of paleoclimate. Coupled radiocarbon and U-series dates allow
14C to be used as a tracer of ocean circulation rate in the same manner as it is used in the modern ocean. Diagenetic alteration
of coral skeletons on the seafloor requires a thorough cleaning of contaminating phases of carbon. In addition, 10% of the
coral must be chemically leached prior to dissolution to remove adsorbed modern CO2. A survey of modern samples from the
full 14C gradient in the deep ocean demonstrates that the coralline CaCO3 records the radiocarbon value of the dissolved
inorganic carbon.
The radiocarbon content of dissolved inorganic carbon (DIC) in seawater is an important tool for
constraining the rate of deep-water circulation. GEOSECS observations constrain the mean over-
turning time of the ocean to be about 800 years (Stuiver et al. 1983). At any one site in the ocean,
considerations of both mixing and in-situ aging are important in determining the seawater D14C. In
the modern western Atlantic for instance, there is a 100 range in D14C, but only about 150 years
worth of aging (equivalentto about 20) since the water last was at the surface (Broecker and Peng
1982). In addition to mixing, D14C ventilationage calculationsfrom radiocarbon are complicated by
the addition of nuclear bomb produced 14C during the era of atmospheric testing. Some early mea-


Source: Adkins, Jess F. - Division of Geological and Planetary Sciences, California Institute of Technology


Collections: Environmental Sciences and Ecology; Geosciences