TUSCAN FORMATION VOLCANICLASTIC DEBRIS FLOW DEPOSITS FROM ANCIENT MT. YANA: USING THE MYANA EXPLORER APP TO COMMUNICATE GEOLOGIC HISTORY TO THE PUBLIC

The Tuscan Formation is a series of volcaniclastic deposits consisting of breccia, conglomerate, sandstone, and mudstone beds emplaced by debris flows from Mt. Yana. Located 40 km south of the Lassen Volcanic Center, Mt. Yana is an eroded 3 Ma stratovolcano of the ancient Cascades (Clynne et al., 2010). Tuscan Formation deposits are in contact with and derived from Mt. Yana lavas (Clynne and Muffler, 2017). Geochemical and textural correlations of pyroxene-phyric andesites that are present in Mt. Yana lavas and Tuscan Formation clasts (Lindberg et al., 2006 and Cortino et al., 2007) are used to correlate source lavas with debris flow deposits. MYana Explorer, a newly developed educational app-based guide for the public, presents observations and geologic analyses that explain relationships between the Tuscan Formation and eroded Mt. Yana. MYana Explorer includes 12 different stops exploring the geology of the Tuscan Formation and Mt. Yana (in Chico CA and within a 2-hour drive from Chico, respectively). Three stops explore the Tuscan Formation and focus on the concept of geologic time. In two locations, users observe the base of the Tuscan Formation, which is a nonconformity where debris flows were deposited on the Lovejoy Basalt Formation (15-16 Ma; Coe et al., 2005) and on Carboniferous metabasement (Clynne et al., 2010). This expression of geologic time is important to geologists and is a valuable educational opportunity to explain natural history to the public. MYana Explorer app users will learn how Mt. Yana was built through dike emplacement and eruptions of lava, how it eroded to a now nearly unrecognizable volcano, and how this resulted in the emplacement of the Tuscan Formation. The app will help users understand their local geology including, volcanic erosional processes, volcaniclastic deposits, geologic time, and the geology of proximal and distal volcanic facies associated with eroded stratovolcanoes in the Cascade range. The MYana Explorer app will be available free online in the spring of 2022.