Fig. 7

⁴⁰Ar/³⁹Ar step heating profiles for zinnwaldite-lepidolite crystal clasts from Lithium-rich Tuff samples from the Macusani Volcanic Field. The 2021-MAC-05 age is recalibrated using the concordant inverse isochron ⁴⁰Ar/³⁶Ar ⁴⁰Ar/³⁶Ar intercept of 321.8 ± 0.3.