|Holocene Kamchatka volcanoes||
Institute of Volcanology and Seismology
Global Volcanism Program number
55°08’ N, 160°20’ E, summit elevation 2375 m
Kizimen volcano (Figs.1,2) is a Holocene edifice situated in Shchapina graben, on the southeastern edge of the Central Kamchatka Depression. The volcano is cut by NE-strking faults and deep gullies, which expose the whole suite of its rocks. The only historic eruption of the volcano ("fire flames and black smoke") was reported by local hunters in 1928, however, it should have been a weak one since no deposits of this age are seen at the foot of the volcano.
Kizimen eruptive history shows evolution from large silicic ignimbrite-forming eruptions, alternating with dome-forming events, to moderate mafic effusive eruptions. The volcano started to form in the very beginning of the Holocene time, some 11-12 ka ago, with a series of strong eruptions producing voluminous ignimbrite sheet and thick dacite lava flows. This paroxysm was followed by an extrusive dome growth and minor accompanying eruptions likely to have ended before 9.5 ka BP.
Next large explosive episode took place 7700-7500 14C years BP. It started from moderate eruptions producing pumice falls and culminated in KZ large eruption, which deposited voluminous ignimbrite at the foot of the volcano and ash over large territory at a distance of more than 100 km away from the volcano. This andesite-dacite ash is a good marker for the regions from Bolshoi Semiachik in the south to Kliuchi town and Shiveluch volcano in the north (Fig. 2). This episode was also followed by an extrusive dome formation, which lasted for about 700 years.
About 2900 14C years BP Kizimen produced its last pyroclastic flows, which unlike the older ones, contained both andesite and basaltic andesite material. This event marked the transition to more mafic products and to a different type of acitivity producing lava flows and almost no tephra.
All Kizimen rocks are hornblende-bearing mid-potassic basaltic andesite-andesite-dacite of the calcalkaline series. A prominent feature of Kizimen rocks is a coexistence of olivine and quartz phenocrysts in all the rock varieties and other signs of magma mingling and mixing. Specific characteristics of the Kizimen rocks allowed to suggest that interaction between silicic and mafic melts likely occurs by frequent recharge of mantle magma to a mid to upper crustal chamber (Melekestsev et al., 1995; Churikova et al., 2001).
Churikova et al. (2001) point out the similarity of Kizimen to Unzen volcano in Japan in terms of structural position, types of eruption and petrological characteristics.
Melekestsev IV, Ponomareva VV, Volynets ON (1995) Kizimen volcano, Kamchatka - a future Mount St.Helens? Journal of Volcanology and Geothermal Research 65: 205-226
Braitseva OA, Ponomareva VV, Sulerzhitsky LD, Melekestsev IV, Bailey J (1997) Holocene key-marker tephra layers in Kamchatka, Russia. Quaternary Research 47/2: 125-139
Churikova TG, Dorendorf F, Wörner G. (2001) Sources and fluids in the mantle wedge below Kamchatka, evidence from across-arc geochemical variation. Journal of Petrology, 42/8: 1567-1593
Churikova T, Ivanov B, Eichelberger J, Trusov S, Gardner J, Belousov A, Browne B, Izbekov P, Wörner G. (2001) Kizimen Volcano: An Unzen-like Magma System in Kamchatka. Eos Trans. AGU 82 (47), Fall Meet.Suppl., Abstract V42D-1062.