TRACE-ELEMENT CONCENTRATIONS IN CONODONTS MEASURED BY THE BOCHUM PROTON MICROPROBE

The Proton Microprobe at Bochum has been used to study trace element c ontents and elemental distributions in a suite of Devonian and Triassi c conodonts, skeletal parts of marine invertebrates composed of the CO 3- and F-rich modification of apatite (francolite). The conodonts cont ain a plethora of substituting elements (Mn, Fe, Sr, Y, light REE) at high concentrations, and linescans and elemental maps reveal preferent ial enrichments of many of these elements around skeletal rims. This o bservation tends to support the concept of post-depositional chemical alteration of the conodonts, but within an environment that still refl ects the ambient marine conditions. Consequently, despite the high deg ree of substitution in the apatite structure, the Sr isotope signals o f ancient seawater may still be retained by the samples. (C) 1997 Else vier Science B.V.