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Holocene Key-Marker Tephra Layers in Kamchatka, Russia

1997; Cambridge University Press; Volume: 47; Issue: 2 Linguagem: Inglês

10.1006/qres.1996.1876

1096-0287

O A Braitseva, В. В. Пономарева, L. D. Sulerzhitsky, И. В. Мелекесцев, J.C. Bailey,

Geochemistry and Geologic Mapping

Detailed tephrochronological studies in Kamchatka Peninsula, Russia, permitted documentation of 24 Holocene key-marker tephra layers related to the largest explosive eruptions from 11 volcanic centers. Each layer was traced for tens to hundreds of kilometers away from the source volcano; its stratigraphic position, area of dispersal, age, characteristic features of grain-size distribution, and chemical and mineral composition confirmed its identification. The most important marker tephra horizons covering a large part of the peninsula are (from north to south; ages given in 14 C yr B.P.) SH 2 (≈1000 yr B.P.) and SH 3 (≈1400 yr B.P.) from Shiveluch volcano; KZ (≈7500 yr B.P.) from Kizimen volcano; KRM (≈7900 yr B.P.) from Karymsky caldera; KHG (≈7000 yr B.P.) from Khangar volcano; AV 1 (≈3500 yr B.P.), AV 2 (≈4000 yr B.P.), AV 4 (≈5500 yr B.P.), and AV 5 (≈5600 yr B.P.) from Avachinsky volcano; OP (≈1500 yr B.P.) from the Baraniy Amfiteatr crater at Opala volcano; KHD (≈2800 yr B.P.) from the “maar” at Khodutka volcano; KS 1 (≈1800 yr B.P.) and KS 2 (≈6000 yr B.P.) from the Ksudach calderas; KSht 3 (A.D. 1907) from Shtyubel cone in Ksudach volcanic massif; and KO (≈7700 yr B.P.) from the Kuril Lake-Iliinsky caldera. Tephra layers SH 5 (≈2600 yr B.P.) from Shiveluch volcano, AV 3 (≈4500 yr B.P.) from Avachinsky volcano, OP tr (≈4600 yr B.P.) from Opala volcano, KS 3 (≈6100 yr B.P.) and KS 4 (≈8800 yr B.P.) from Ksudach calderas, KSht 1 (≈1100 yr B.P.) from Shtyubel cone, and ZLT (≈4600 yr B.P.) from Iliinsky volcano cover smaller areas and have local stratigraphic value, as do the ash layers from the historically recorded eruptions of Shiveluch (SH 1964 ) and Bezymianny (B 1956 ) volcanoes. The dated tephra layers provide a record of the most voluminous explosive events in Kamchatka during the Holocene and form a tephrochronological timescale for dating and correlating various deposits.