HOLOCENE KEY-MARKER TEPHRA LAYERS IN KAMCHATKA, RUSSIA

Detailed tephrochronological studies in Kamchatka Peninsula, Russia, p ermitted documentation of 24 Holocene key-marker tephra layers related to the largest explosive eruptions from 11 volcanic centers. Each lay er was traced for tens to hundreds of kilometers away from the source volcano; its stratigraphic position, area of dispersal, age, character istic features of grain-size distribution, and chemical and mineral co mposition confirmed its identification, The most important marker teph ra horizons covering a large part of the peninsula are (from north to south; ages given in C-14 yr B.P.) SH2 (approximate to 1000 yr B.P.) a nd SH3 (approximate to 1400 yr B.P.) from Shiveluch volcano; KZ (appro ximate to 7500 yr B.P.) from Kizimen volcano; KRM (approximate to 7900 yr B.P.) from Karymsky caldera; KHG (approximate to 7000 yr B.P.) fro m Khangar volcano; AV(1) (approximate to 3500 yr B.P.), AV(2) (approxi mate to 4000 yr B.P.), AV(4) (approximate to 5500 yr B.P.), and AV(5) (approximate to 5600 yr B.P.) from Avachinsky volcano; OP (approximate to 1500 yr B.P.) from the Baraniy Amfiteatr crater at Opala volcano; KHD (approximate to 2800 yr B.P.) from the ''maar'' at Khodutka volcan o; KS1 (approximate to 1800 yr B.P.) and KS2 (approximate to 6000 yr B .P.) from the Ksudach calderas; KSht(3) (A.D. 1907) from Shtyubel cone in Ksudach volcanic massif; and KO (approximate to 7700 yr B.P.) from the Kuril Lake-Iliinsky caldera. Tephra layers SH5 (approximate to 26 00 yr B.P.) from Shiveluch volcano, AV(3) (approximate to 4500 yr B.P. ) from Avachinsky volcano, OPtr (approximate to 4600 yr B.P.) from Opa la volcano, KS3 (approximate to 6100 yr B.P.) and KS4 (approximate to 8800 yr B.P.) from Ksudach calderas, KSht(1) (approximate to 1100 yr B .P.) from Shtyubel cone, and ZLT (approximate to 4600 yr B.P.) from Il iinsky volcano cover smaller areas and have local stratigraphic value, as do the ash layers from the historically recorded eruptions of Shiv eluch (SH1964) and Bezymianny (B-1956) volcanoes. The dated tephra lay ers provide a record of the most voluminous explosive events in Kamcha tka during the Holocene and form a tephrochronological timescale for d ating and correlating various deposits. (C) 1997 University of Washing ton.