Data Supplement accompanying manuscript by Ring et al.: Timing of the switchover from thrusting to normal faulting in deep parts of the Cretan nappe pile, Greece

We report two fault gouge ages of ~30 and ~25 Ma from sample GR18-5 collected at the contact zone between the high-pressure Phyllite-Quartzite Unit and the overlying, weakly metamorphosed Tripolitza Nappe in central Crete, southern Aegean Sea, Greece. This contact, the Damasta shear zone, is commonly regarded as a segment of the Cretan Detachment, the age of which is not well known. The dated gouge shows early top-to-the-S kinematic indicators, with some weak indication for a top-to-the-N reactivation. Illite/muscovite grain-size fractions of 0.5-0.2 mm and 0.2-0.1 mm yielded, within error, similar K–Ar ages of ~30 Ma. These internally consistent ages can be interpreted as the timing of a first faulting event, which we interpret to be associated with the first set of top-to-the-S kinematic indicators. Three K–Ar ages of ~25 Ma were obtained from two separate <0.1 mm and a single >0.2 mm grain-size fraction. This age reflects reworking of the fault gouge and is interpreted to data a phase of top-to-the N shearing. Because the ~25 Ma age overlaps with high-pressure metamorphism and subsequent rapid exhumation of the Phyllite-Quartzite Unit, we interpret the age to be related to the Cretan Detachment in central Crete. Published data show that the upper parts of the Phyllite-Quartzite Unit as part of the Upper Ionian HP belt started to be underthrust to the north between 36 and 29 Ma. Therefore, we relate the fault gouge ages of ~30 Ma to the underthrusting event.