STRONTIANITE IN CORAL SKELETAL ARAGONITE

An x-ray spectroscopic study of scleractinian coral skeletons indicate d that, although some strontium substitutes for calcium in the aragoni te structure, at concentrations of about 7500 parts per million, as mu ch as 40 percent of the strontium resides in strontianite (SrCO3). A d oubler peak in the Fourier transform of the extended x-ray absorption fine structure of the coral corresponded to six metal and 13 oxygen ne ighbors surrounding strontium at about 4.05 angstroms in strontium-sub stituted aragonite and at about 4.21 angstroms in strontianite. Thus, the mechanism of the temperature-sensitive partitioning of strontium b etween seawater and coral skeleton used for paleothermometry is unexpe ctedly complex.