FORMATION OF POLYGENETIC BUROZEMS ON RED RESIDUE OF RIKORD ISLAND (PETER THE GREAT GULF, PRIMORSKII KRAI)
B.F. PSHENICHNIKOV1, M.S. LYASHCHEVSKAYA2, N.F. PSHENICHNIKOVA2
1Far Eastern Federal University, 690050, Vladivostok, ul. Sukhanova, 8, Russia
bikinbf@mail.ru
2Pacific Geographical Institute, Far Eastern Branch, Russian Academy of Sciences, 690041, Vladivostok, ul. Radio, 7, Russia
lyshevskay@mail.ru
Keywords: полигенетичность, спорово-пыльцевой анализ, радиоуглеродное датирование, климат, грану лометрический состав, голоцен, polygeneticity, spore-pollen analysis, radiocarbon dating, climate, particle-size distribution, Holocene
Abstract
This research focuses on Holocene polygenetic burozems on red residue (Rikord Island). We determined the particle-size distribution, analyzed the spore-pollen composition of genetic soil horizons, and obtained burozem radiocarbon datings. It is shown that the upper part of the profile is dominated by the fraction of coarse silt whose content gradually decreases down the profile, followed by a marked increase at depths from 145 to 180 cm. This indicates an active cyclonic activity and sheet wash in the Late Holocene, which is also confirmed by a high level of adventitious Pinus densiflora pollen in AYEL horizon spore-pollen spectra. Profile distribution patterns for silt and clay fractions give evidence of clearly pronounced argillification of the lower part of the profile caused by intense processes of weathering at the period of formation of the ВМС and С horizons (LU 7127:4530 ± 180 BP). Silica accumulation in the AYEL horizon is due to podzolization in the cold climatic conditions of the Late Holocene (LU-7563:1550 ± 110 BP), which was reflected in the composition of spore-pollen spectra: a decrease in the amount of pollen from broad-leaved species and an increase in pollen from small-leaved species (birch). Palynological data indicate that the C and BMC horizons of the profiles under study largely formed in warmer (compared to the present time) climatic conditions of the Middle Holocene, whereas the BM horizon formed in the latter part of the Middle Holocene in cli matic conditions similar to the present-day conditions. The AYBM, AYEL and AY horizons formed in colder (than present-day) climatic conditions of the Late Holocene, as indicated by recent deluvial deposits overlying red residue and giving rise to poly genetic burozems. The O horizon (leaf litter) formed under present-day climatic conditions, with a general trend in climate warming.
|
