FCs-EK: a new sampling of the Fish Canyon Tuff ⁴⁰ Ar/ ³⁹ Ar neutron flux monitor

Abstract

Abstract Sanidine from the Fish Canyon Tuff is regularly used as a neutron flux monitor by 40 Ar/ 39 Ar geochronologists. A new sampling of the Fish Canyon Tuff (denoted FCs-EK) has yielded sanidine that relative to FC-2 is confirmed here to have an R value of 0.9997±0.0100, which is indistinguishable from 1. The new sample will allow for continuity as many 40 Ar/ 39 Ar laboratories have exhausted their supplies of FC-2. FCs-EK is now available in significant quantities from the Scottish Universities Environmental Research Centre. Supplementary material: A table of Ar isotopic data is available at http://www.geolsoc.org.uk/SUP18632 .