Adagdak reported activity

Event Name : Adagdak Domes

Start: 210000 (± 50000 Years)

Years BP Ar/Ar

Lava dome:

Eruption Type:	Explosive
Eruption Product:	other
Chem	Yes
Other	other

Description: From Baten (2002): "Mt. Adagdak (650 m asl) was built from three stages of volcanism (Figure 1.5 [in original text])."

"Three small extrusive domes formed during the last stage of volcanism. One is located on the southeast flank of the shield volcano cone and two are at the summit of the younger cone (Myers and Frost, 1994). Coats (1956) temporally correlated these domes based on topography. The domes can also be correlated in age to the features on which they grew (Myers and Frost, 1994). The summit domes were emplaced after the young cone, and the flank dome was emplaced after the shield building stage but potentially before the summit domes."

"...three domes, one of which has a data of 0.21+/-0.05 Ma."

From Myers and Frost (1994): "The last volcanic activity of Mount Adagdak is represented presumably by three, small extrusive domes. Two of these units occupy the younger composite cone’s crater whereas the third occurs on the southeast flank of the older composite cone (Fig. 2 [in original text]). Although Coats (1956) correlated this dome with the summit domes on the basis of topographic form, it could be related temporally to the older composite cone upon which it rests."

"Although similar to the rest of the volcanic suite, the volcanic domes differ from one another geochemically. The flank dome consists of basalts and basaltic andesites (50.8-53.6 wt. % SiO2) with high alumina (~19 wt. %), 9-10% CaO, and less than 1% K2O. In contrast, the summit domes have 59.5 to 62.9 wt. % silica, low Al2O3 (~17 wt. %) and CaO (6.3-6.8%) and are enriched in K2O (1.33-1.53% vs 0.85-0.97%, respectively)."

From Coats (1956): "Two hornbelde andesite domes occur in the crater of the younger composite cone, and a basalt dome occurs low on the southern flank of the older one. The northern and larger of the two crater domes shows planar banding, which trends roughly parallel to the contact and dips steeply."