The Glen Torridon stratigraphic sequence marks the transition from the low energy lacustrine-dominated Murray formation (Mf) (Jura member: Jm) to the more diverse Carolyn Shoemaker formation (CSf) (Knockfarril Hill member: KHm; Glasgow member: Gm), indicating a change in overall depositional setting. Alpha Particle X-ray Spectrometer (APXS) results and statistical analysis reveals that the bulk primary geochemistry of Mf targets are broadly in family with CSf targets, but with subtle compositional and diagenetic trends with increasing elevation. APXS results reveal significant compositional differences between Jm_GT and the stratigraphically equivalent Jura on Vera Rubin ridge (Jm_VRR). APXS data defines two geochemical facies (high-K or high-Mg) with a strong bimodal grain distribution in Jm_GT and KHm. The contact between KHm to Gm is marked by abrupt sedimentological changes but a similar composition for both. Away from the contact, the KHm and Gm plot discretely, suggesting a zone of common alteration at the transition and/or a gradual transition in provenance with increasing elevation in the Gm. APXS results point to a complex history of diagenesis within Glen Torridon, with increasing diagenesis close to the Basal Siccar Point unconformity on the Greenheugh pediment, and with proximity to the beginning of the clay sulfate transition. Elemental mobility is evident in localized enrichments or depletions of Ca, S, Mn, P, Zn, Ni. The highly altered Hutton interval, in contact with the unconformity on Tower butte, is also identified on Western Butte, indicating that the “interval” was once laterally extensive.
