V. B. Bazarova, M. S. Lyashchevskaya, T. R. Makarova
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引用次数: 0
Abstract
The issues of the environmental evolution of the western sector of the Khanka valley and the evolution of Lake Khanka are considered for the maxima of the last glaciation and Late Pleistocene lacustrine transgression. The lithological indicators and results of diatom analysis of lacustrine sediments of Lake Khanka indicate two sedimentation conditions over the period of 24.0–19.0 cal ka BP: an oligotrophic–mesotrophic moderately swampy shallow reservoir with an unstable level and a relatively deep lake. The maximum of the transgression occurred at ~19.6 cal ka BP, when the lake level was 1.5–2.0 m higher than at present for the first time. Four phases of the vegetation evolution in the western sector of the Khanka valley are distinguished: I, birch–larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II, dark coniferous taiga with dwarf pine and a small amount of broad-leaved trees (22.8–20.6 cal ka BP); III, spruce forests with dwarf pine, fir, larch, and rare oak (20.6–20.1 cal ka BP); and IV, light birch forests and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two cooling phases are registered at the Khanka valley (~24.0 cal ka BP (cooling maximum) and 20.6 cal ka BP) and one warming phase (∼22.8 cal ka BP), which are correlated with the detailed global Greenland glacier records. The driest periods occurred at 21.7–21.2 cal ka BP. The quantitative characteristics of climate events are reconstructed from modern plant analogs.
摘要 研究了汉卡谷地西段的环境演变问题，以及汉卡湖在末次冰川期和晚更新世湖泊横断期的演变情况。汉卡湖湖底沉积物的岩性指标和硅藻分析结果表明，在公元前 24.0-19.0 卡期间有两种沉积条件：一种是水位不稳定的寡营养-中营养中度沼泽浅层水库，另一种是相对较深的湖泊。横断面的最大值出现在约 19.6 cal ka BP，当时的湖面首次比现在高出 1.5-2.0 米。汉卡谷地西段的植被演变分为四个阶段：I，桦木-落叶松mari，伴有桤木和寒带灌木（23.8-22.8 cal ka BP）；II，深色针叶泰加林，伴有矮松树和少量阔叶树（22.8-20.6 cal ka BP）；III，云杉林，伴有矮松树、冷杉、落叶松和稀有橡树（20.6-20.1 cal ka BP）；IV，浅色桦木林和落叶松mari，伴有寒带灌木（20.1-19.0 cal ka BP）。汉卡谷地有两个降温阶段（约 24.0 cal ka BP（降温最大值）和 20.6 cal ka BP）和一个升温阶段（22.8 cal ka BP），这与格陵兰冰川的全球详细记录相关。最干旱时期出现在 21.7-21.2 cal ka BP。气候事件的定量特征是通过现代植物类似物重建的。
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