Physical Sciences and Mathematics Commons^™

Mineralogy And Petrology Of Lava Flows (Tertiary-Quaternary) In Southeastern Idaho And At Black Mountain, Rich County, Utah, Barbara J. Puchy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Lava flows of Tertiary-Quaternary age occur in Enoch Valley, Upper Valley, and Slug Valley in southeastern Idaho. The basalts in Upper Valley and Enoch Valley contain olivine (Fo₆₉ to Fo₃₇), plagioclase (An₆₂ to An₃₉), augite and Fe-Ti oxides. The lava in Slug Valley lacks plagioclase, but contains sanidine (Or₇₀ to Or₅₆) with a trace of biotite and amphibole, and thus, has been termed alkali trachyte.

Black Mountain, on the eastern side of Bear Lake, northeastern Utah, is capped by basalt. Minerals present include olivine (Fo₈₃ to Fo₇₂), plagioclase …