Event Name : Trident 143000 yBP
|Stop: 143000 (± 8000 Years) || Years BP K-Ar || |
|Lava flow: ||
|Eruption Product: || andesite ||
From Hildreth and others (2003): "For East Trident, a near-basal andesitic lava flow resting on oxidized breccia at glacier level on the nose of the north-west prong (which separates Glaciers 1 and 2, fig. 3 [in original text]) yields a weighted mean age of 143+/-8 ka, analytically indistinguishable from an age of 142+/-15 ka on a 100-m-thick dacitic lava flow that caps part of the northeast ridge of the edifice. These samples appear to bracket most of the dozens of lava flows that make up the edifice, suggesting that eruptive activity at the small East Trident cone was short lived. The ages indicate not only that East Trident is the oldest member of the Trident group but also that it predates the oldest recognized eruptive products of neighboring Katmai and Mageik Volcanoes (Hildreth and Fierstein, 2000; Hildreth and others, 2000)."
"An analytically indistinguishable age of 143+/-8 ka for a near-basal andesitic lava flow low on the northwest ridge suggests, however, that activity at the small East Trident cone was short lived, late in the middle Pleistocene. These ages also indicate that East Trident is the oldest edifice of the Trident group and is, indeed, older than neighboring Katmai and Mageik Volcanoes, as well."