The 92 ± 1 Ma Deadman pluton is a massive, circular, felsic intrusion of alkalic composition that is part of the Tombstone plutonic suite. It intrudes Neoproterozoic Hyland Group strata within the Dawson thrust sheet in the northernmost Selwyn Basin. Paleomagnetic determinations have isolated a stable characteristic remanent magnetization (ChRM) direction, in magnetite, for 237 specimens from 23 sites. The sites are in three plutonic phases, in three dykes cutting the pluton as well as their contact zones, and in the pluton¿s contact-zone skarn. The ChRM at all sites is coeval with pluton crystallization. The ChRM directions of all sites form one population with a mean direction of declination = 333.0°, inclination = 76.8° (95 = 2.6°, k = 139, N = 23), giving a paleopole of 144.9°E, 78.5°N (p = 4.5°, m = 4.8°) that is significantly different, at 95% confidence, from the coeval North American cratonic paleopole. This discordance is attributed to post-emplacement, northward displacement of at least several tens of kilometres of the Dawson thrust sheet, possibly along the Dawson thrust fault. The result is the beheading of the Deadman pluton and rotating its head as it was driven up the curved frontal ramp of the thrust fault. This evidence indicates at least local, but significant, post-mid- Cretaceous deformation within rocks underlying northern Selwyn Basin.
