Event Name : Aniakchak Precaldera Pyroclastic
|Start: 9500 || Years BP Tephrochronology || |
|Stop: 7000 || Years BP Tephrochronology || |
|Pyroclastic flow, surge, or nuee ardente: ||
From Bacon and others (2014): "A meter or more thickness of unconsolidated deposits overlie Aniakchak I material and underlie the Black Nose Pumice in the exposure north of The Gates shown in figure 6C ("unconsolidated deposits"). The juvenile clasts in these deposits are dacite pumice. The sequence consists of ≤1 cm of buff ash, 1 cm of gray ash, 15 cm of pumice fall with obsidian chips, 5 cm of dark gray ash, 1 m of pumice fall with ≤0.5 cm obsidian chips and rare bombs as large as 30 cm, and 1 m of ashy probable surge deposit. The two uppermost beds are erosionally truncated. Additional work on tephras, below ash from Black Peak in flank exposures such as shown in figure 6A and in distal exposures studied by VanderHoek (2009), may establish correlations with the caldera rim deposits."