DETERMINING THE VALIDITY OF MICROWAVE PLASMA ATOMIC EMISSION SPECTROSCOPY IN QUANTITATIVE ANALYSIS OF ORDOVICIAN BRACHIOPODS

Microwave plasma atomic emission spectroscopy (MP-AES) is a well-established method to quantify the chemical content of various geologic samples. However, there has been very little exploration in using MP-AES for fossil analysis. The sensitivity and detection limit of MP-AES is intermediate between two common analysis techniques (flame atomic absorption spectroscopy; inductively-coupled plasma mass spectrometry). We apply MP-AES to fossil specimens, in order to determine if frequently-studied elements are capable of being detected and if the instrument is sensitive enough to distinguish between fossil concentrations. Shell fragments of fossilized brachiopod specimens sampled from the Dillsboro formation in Southeastern Indiana were dissolved in concentrated nitric acid and sent through the MP-AES, analyzing for calcium, manganese, magnesium, strontium, and iron content. These elements are useful for interpreting diagenesis and palaeothermometry, and have been detected using MP-AES in different geologic materials. After analyzing fragments from several brachiopod genera, including Hebertella, Strophomena, and Rafinesquina, it was determined that all five elements are capable of being detected and distinguishable from other specimens. This suggests that MP-AES could be employed by scientists studying diagenesis or palaeothermometry through fossilized brachiopods.