Data for: Microstructurally-controlled versus bulk fault gouge K-Ar dating

Supplement material 1: Description of the K-Ar and XRD methods. Supplement material 2: Interpreted XRD diffractograms of (a) FC-1, (b) DZ-1a (c) DZ-1b, (d) FC-2, (e) DZ-2a and (f) DZ-2b. Supplement material 3: XRD data, normalized to 100 wt%, and illite crystallinity (Kübler Index, given in Δ°2θ). Lower detection limit of XRD results is 1-2 wt% and uncertainty for quantification is c. 2-3 wt%. Kübler indices are standardized according to Warr (2018).