40Ar/39Ar dating of the SP and Bar Ten lava flows AZ, USA: Laying the foundation for the SPICE cosmogenic nuclide production-rate calibration project

► The 40Ar/39Ar age of the quartz-bearing basaltic SP flow is 72 ± 4 ka. ► 3He and 21Ne production rates (PR) in SP pyroxene (px): 119 ± 8 and 26.8 ± 1.9 at/g/yr. ► 3He and 21Ne PRs in (px) at upper Bar Ten flow: 118 ± 13 and 22.8 ± 2.5 at/g/yr. ► Precise 40Ar/39Ar ages distinguish basalt flows that may be as close as 4 ka. ► SP flow will also be used for PR calibration of 10Be, 14C, 26Al, and 36Cl.