Kinematic indicators in fault gouge: tectonic analog for soft-bedded ice sheets

Polished slip planes resulting from Basin and Range detachment faulting of mid-Tertiary volcaniclastics are well exposed at Lake Pleasant, Arizona, U.S.A. Slip planes show erosional features formed by abrasion below moving sheets of gouge (coarse-grained diamict) during repeated faulting and shearing. Tectonically generated forms are identical to those found in glaciated terrains. Slip planes show ‘rat-tail’ ridges and grooves (‘ridge-in-groove …