Clay mineralogy, crystallinity, and K-Ar ages of illites within the Polish Zechstein Basin; implications for the age of Kupferschiefer mineralization

Sir: We are pleased to respond to J. Nawrocki’s comment. It gives us an additional opportunity to articulate our ideas on the significance of the K-Ar ages of illites with respect to Kupferschiefer ore genesis (Bechtel et al., 1999). Nawrocki perhaps has overstated our intent by writing that we used paleomagnetic data to verify our indirect method for measuring the age of the Kupferschiefer mineralization event. The ages in question were estimated ages of diagenetic illite in both the abstract and in the main body of the paper. In the closing sentence of the abstract, we wrote that our results suggest that the formation of diagenetic illite was induced by the mineralizing event. We did not claim verification of the indirect dating method, and in the concluding statement that Nawrocki specifically criticized, we claimed only that the ages we inferred are, within limits of error, in agreement with the ages from paleomagnetic data (Jowett et al., 1987a). We did not (could not) claim agreement with Nawrocki’s then unpublished data that the pole position of …