Okmok reported activity

Event Name : Okmok 1700000 yBP

Start: 1700000 (± 200000 Years)

Years BP K-Ar

Lava flow:

Eruption Type:	Effusive
Eruption Product:	basalt
Other	mafic

Description: From Miller and others (1998): "Construction of the pre-caldera volcano began in late Tertiary or early Quaternary time. Two whole-rock K-Ar analyses of a sample of basaltic lava are 1.7+/-2 and 2.1+/-2 m.y. (Bingham and Stone, 1973). Basaltic flows and pyroclastics compose most of the older rocks (unit Qbm, fig. 67 [in original text]); flows are more voluminous than pyroclastic deposits (see Byers, 1959, plate 41)."

"Flows and pyroclastic beds dip radially from the caldera at less than 5 degrees in most sectors, except for local steepening and reversal of dips at former vents. Such radial dips suggest that the older complex was a central volcano with parasitic vents."