Buzzard Creek reported activity

Event Name : Buzzard Creek Maars

Start: 3000

Years BP C-14 (cal)

Tephrafall:
Maar, tuff cone, tuff ring:

Eruption Type:	Explosive
Eruption Product:	basalt
Eruption Product:	basalt
MaxVEI:	2
Modal	Yes
Other	mafic

Description: From Andronikov and Mukasa (2010): "Two Buzzard Creek maars located next to the upper stream of Buzzard Creek, along the northern foothills of the central Alaska Range are surrounded by tuff rings which are ∼300 m and ∼70 m in diameter. The volcanic rocks are represented by two main types: volcanic ejecta consisting of small volcanic lapilli (1-5 cm in diameter) and volcanic bombs with a mixture of host rocks fragments, and basaltic lavas. Radiocarbon dates from charcoal samples above and below the basaltic ejecta give an eruption age of ca. 3000 years (Wood and Kienle, 1990; Nye, 2006, pers. comm.). Although volcanic rocks of the Buzzard Creek maars are insignificant in volume, they are interesting tectonically because they occur in a 400 km volcano gap between the Aleutian arc structure and Wrangell Volcanic Field (Richter and others, 1990; Miller and Richter, 1994), and are situated over the northernmost corner of the subducting Pacific Plate."

"Buzzard Creek basalts are dark-grey to brownish-black rocks composed of plagioclase (20-25%), augite (3-5%) and olivine (5-10%) phenocrysts in a fine- to medium-grained groundmass consisting of elongated plagioclase microlites (10-15%), clinopyroxene laths (5-10%), small olivine grains (10-15%), with scattered euhedral magnetite crystals (5-10%), and brownish glass (5-10%). The lavas are often vesicular, and many vesicles have been partially filled by zeolites. Apart from this, the rocks are generally fresh and unaltered. Tiny (up to∼1 cm) spinel lherzolite xenoliths and xenocrysts of Cr-spinel, olivine and Cr-diopside, that are likely disaggregations of the spinel lherzolite xenoliths, are common in the Buzzard Creek lavas. Ejecta lapilli are compositionally similar to the basaltic lava, but contain abundant fragments of the host crustal rocks as well as mantle microxenoliths and xenocrysts often serving as the points of nucleation for the lapilli."

"Wood and Kienle (1990) reported that the Buzzard Creek maars erupted as recently as 3000 years ago. To verify this [Andronikov and Mukasa, 2010] analyzed lava sample 05BZC-1, obtaining 40 Ar/39 Ar ages of -0.12+/-0.06 Ma (plateau), 0.01+/-0.07 Ma (isochron), and -0.02+/-0.06 Ma (total gas) (Fig. 4 [in original text]) which verifies a very young eruption age although the measurements did not yield a usable absolute value."