The Katmai Region, Alaska, and the Great Eruption of 1912

Interpretation of exploration geochemical data for the Mount Katmai Quadrangle and adjacent parts of the Afognak and Naknek quadrangles, Alaska

“…Systematic geologic mapping by Keller and Reiser (1959 and citations therein) summarizes the early work done in the Katmai study area. Additional geologic studies have concentrated on either the 1912 eruption of Novarupta volcano and its associated ash-flow deposit in the Valley ofTen Thousand Smokes (for example, Fenner, 1920), or paleontology and stratigraphy along Shelikof Strait (see citations in Riehle and others, in press). Here, we describe briefly the geology of the Katmai study area in order to provide a geologic framework for the interpretation of the geochemical results.…”

“…Samples of the small fumarolic vents exposed at Novarupta (T. 22 S., R. 36 W.; site 120, table 14) were analyzed to evaluate the metal anomalies associated with the rootless fumaroles that formed following the eruption of 1912 (Fenner, 1920). Keith (1984) reported on zones of argillic alteration in the fumarole vents and observed alunite in active hot springs at Novarupta in 1982.…”

“…The lava flows are mainly andesite or dacite, whereas the domes range from dacite to rhyolite. Ash-flow tuffs, chiefly dacite to rhyolite, are present along the southern margin of the Katmai study area, in the Valley of Ten Thousand Smokes (formed during the 1912 Novarupta eruption ;Fenner, 1920;Curtis, 1968;Hildreth, 1983Hildreth, , 1987, and at Kaguyak Crater. Pumice deposited during the 1912 Novarupta eruption is more than I m thick in the area extending from the head of the Valley of Ten Thousand Smokes east to Shelikof Strait (J.E.…”

Pyroclastic nomenclature in New Zealand

“…Lacroix (1903) had already given the name "nuee ardente" to the type of eruption observed at Pelee and Soufriere in 1902, whereby dense mixtures of pyroclastic materials accompanied by billowing ash clouds swept down the sides of the volcanoes to form deposits at the base. Fenner (1920) and, later, Griggs (1922) both described the Katmai phenomenon as an incandescent sand flow. Marshall (1932) pointed out that "sheets of acid volcanic .rocks" that cover a wide area in the Central North Island of New Zealand were usually called rhyolites, but had had a much greater fluidity than that normally associa'ed with rhyolite lavas.…”

“…He referred to the former as "the great hot mud-flow". Fenner (1920) commented that the deposit was erupted as a "dry, highly heated mass of sand and pumice rather than a water-bearing mud" (p. 577), and that its exact counterpart did not appear to have been described elsewhere. He stated (p.605) that "the extrusion and inflation of the magma gave rise to a great ash-or sand-flow, analogous to the nU!…”