EXPLOSIVITY OF PLEISTOCENE CINDER CONES IN THE LASSEN REGION: INSIGHTS FROM INTEGRATED TEXTURAL AND GEOCHEMICAL ANALYSIS

Cinder cones are one of the most common expressions of volcanism in the Lassen region of the Cascade Arc, yet their explosivity and hazard potential remain poorly constrained. Here, we use a textural and compositional analysis to characterize the proximal scoria deposit of the Late Pleistocene eruption of Poison Butte, a cinder cone ~13 km NE of Lassen peak. Poison Butte is a unit of the Poison Lake Chain, a sequence of basaltic cinder cones following a NW-SE lineament. Scoria samples were collected from an exposed 1m section of cone and analyzed for texture and componentry. We find that variations in vesicle size and crystal size distributions indicate a dynamically explosive eruptive episode with shifting phases. Through a comparison of observation-linked studies of Paricutin (Pioli et al., 2008) and Mt Etna (Polacci et al., 2006), we hypothesize the eruptive phases ranged from Fire Fountaining events to near Violent Strombolian paroxysms. Lastly, we integrate our data with previous work from the youngest cinder cone in the Lassen Volcanic Center, Cinder Cone (erupted 1666; Marks, 2012) in order to gain further insight into regional cinder cone eruption dynamics and inform future hazard models.