Physical Volcanology and geochemistry of Upsal Hogback Volcano, Fallon, Nevada, USA

Upsal Hogback volcano is a tuff cone built up from phreatomagmatic eruptions that is located near the city of Fallon, Nevada. It is composed of indurated basaltic ash and lapilli tuff with abundant basaltic bombs. The edifice consists of the north complex (1 vent), and the south complex (3 vents). The edifice has also been severely eroded by glacial Lake Lahontan, obscuring the original morphology of the volcano, making it look similar to a tuff ring and not a tuff cone. Geochemical analysis of bomb samples from Upsal Hogback show that the north and south complexes are geochemically distinct but still have a similar aesthenospheric mantle source. The magma supplying the volcano originated from a spinel peridotite or low percent garnet mantle source. Neighboring volcanic centers, Soda Lakes and Rattlesnake Hill, also have similar mantle sources and also are volcanic types on the phreatomagmatic spectrum.