Primary U distribution in scleractinian corals and its implications for U series dating
Robinson, Laura F.
Adkins, Jess F.
Fernandez, Diego P.
Burnett, Donald S.
Gagnon, Alexander C.
MetadataShow full item record
In this study we use microsampling techniques to explore diagenetic processes in carbonates. These processes are important as they can affect the accuracy of U series chronometry. Fission track maps of deep-sea scleractinian corals show a threefold difference between the minimum and maximum [U] in modern corals, which is reduced to a factor of 2 in fossil corals. We use micromilling and MC-ICP-MS to make detailed analyses of the [U] and δ234Uinitial distributions in corals from 218 ka to modern. Within each fossil coral we observe a large range of δ234Uinitial values, with high δ234Uinitial values typically associated with low [U]. A simple model shows that this observation is best explained by preferential movement of alpha-decay produced 234U atoms (alpha-recoil diffusion). Open-system addition of 234U may occur when alpha-recoil diffusion is coupled with a high [U] surface layer, such as organic material. This process can result in large, whole-coral δ234Uinitial elevations with little effect on the final age. The diagenetic pathways that we model are relevant to both shallow-water and deep-sea scleractinian corals since both exhibit primary [U] heterogeneity and may be subject to U addition.
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 7 (2006): Q05022, doi:10.1029/2005GC001138.
Showing items related by title, author, creator and subject.
Coral calcification : insights from inorganic experiments and coral responses to environmental variables Holcomb, Michael (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2010-02)Coral calcification is examined using a laboratory model and living corals. In the laboratory model, abiogenic aragonite formed at high saturation state (Ω>~20) had a granular appearance and was enriched in trace elements, ...
Comment on "Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals" by R.G. Fairbanks et al. (Quaternary Science Reviews 24 (2005) 1781-1796), and "Extending the radiocarbon calibration beyond 26,000 years before present using fossil corals" by T.-C. Chiu et al. (Quaternary Science Reviews 24 (2005) 1797-1808). Reimer, Paula J.; Baillie, Mike G. L.; Bard, Edouard; Beck, J. Warren; Blackwell, Paul G.; Buck, Caitlin E.; Burr, George S.; Edwards, R. Lawrence; Friedrich, Michael; Guilderson, Thomas P.; Hogg, Alan G.; Hughen, Konrad A.; Kromer, Bernd; McCormac, Gerry; Manning, Sturt; Reimer, Ron W.; Southon, John R.; Stuiver, Minze; van der Plicht, Johannes; Weyhenmeyer, Constanze E. (2006-02)A recently published radiocarbon calibration curve extending to 50,000 cal BP (Fairbanks et al. 2005) is purportedly superior to that generated by the IntCal working group beyond the end of the tree-ring data at 12,400 ...
Bromage, Erin; Carpenter, Lawrence; Kaattari, Stephen; Patterson, Mark (Inter-Research, 2009-02-11)The induction and regulation of heat shock proteins (hsps) is a significant defense mechanism that can preserve metabolic function and foster recovery from short-term stress events. Present coral sampling methodologies ...