We present results of measurements of cosmogenic 10Be, 26Al and 36Cl, and the indigenous (intrinsic) concentrations of the stable elements Be, Al and Cl in 120-200 kyr old corals from Barbados and Puerto Rico. The concentration levels of these radionuclides in the corals lie in the range 104 to 108 atoms/g. A comparison of the measured nuclide concentrations with those expected to be produced in the corals by nuclear interactions of energetic cosmic radiation shows that (i) the radionuclides 26Al and 36Cl are derived from in situ cosmic ray interactions in the corals after their formation, but that (ii) the radionuclide 10Be owes its provenance in the coralline lattice primarily due to incorporation of dissolved beryllium in seawater in the lattice structure of the corals.
Bibliographical noteFunding Information:
During the initial phases of this study, we were supported by a mini-grant, “CS-13-98”, from the California Space Institute (La Jolla). Critical comments from Martin Frank, John Gosse, Gregory Herzog, T. L. Ku and John Stone are greatly appreciated. One of us (D.L.) acknowledges generous support from Joan Eichen of the Eichen Foundation for carrying out this research, without which this research would not have fructified.