固城湖晚全新世以来的孢粉组合及环境变迁

本文依据固城湖GD钻孔系统的孢粉分析资料,将井深6.3m岩心所做的孢粉图式,结合~(14)C测年,从下面上分为8个孢粉组合带,进而论述了4000年来该区的植被发展和气候的4次冷暖交替的变化。4次冷期约为3.0—2.5KaB.P.2.0—1.5KaB.P.、1.0—0.8KaB.P.和0.4Ka以来。此外,还根据沉积物中的硅藻分析、有机质δ~(13)C值、有机碳含量及历史记载等资料,侧重讨论了气候及人类活动对湖泊环境演变的影响。

Spore-pollen assemblage and environmental change of Gucheng Lake since late holocene

Gucheng Lake, situated in the southeast of Gaocheng County , Jiangsu Province, surrounded by mixed evergreen/deciduous broad-leaved forests, lies between the north and middle subtropical zone in monsoon Asia area. This paper deals mainly with the systematic palynological research on more than 57 samples from a column core with a depth of 6. 2m in Gucheng Lake. According to the spore-pollen diagram, 8 assemblage zones have been distinguished in an ascending order as follows: 1. Cyclobalanopsis- Castanea-Liquidambar zone(6.3-5. lm);2. Pinus-Querous-Polypodiaceae zone(5. 1-4. 15m);3. Cyclobalanopsis-Graminea- Typha zone(4. 15-3. 2m); 4. Gramines- Artemisia - Quercus zone(3. 2-2. 3m); 5. Quercus - Pinus - Castanea zone (2. 3-1. 75m); 6. Graminea- Artemisia - Quercus zone (1. 75-1. 1m) ;7. Quercus - Pinus - Castanea zone(1.1 - 0. 45m) ;8. Pinus -Graminea- Artemisia zone(0. 45-0m) From the above statement, 8 phases of the paleovegetation succession and climate fluctuation seem to be shown in the past 4000 years, and 8 climate periods can be listed in the ascending order for convenience of correlation: 1. 3700-3000 a B. P. : warmer and moist;2. 3000-2500 a B. P. : temperate-cool and a little wet;3. 2500-2000 a B. P. : warm and wet;4. 2000-1500 a B. P. : temperate-cool and a little wet;5. 1500-1000 a B. P. : warm and wet;6. 1000-800 a B. P. : temperate-cool and a little dry;7. 800-500 a B. P. : temperate and wet ;8. 500a B. P. -present: cool and a little dry. Moreover, according to the analysis of stable carbon isotope of organic matter, TOC, diatom and historical records, the influence of climate and human activity on environment is also discussed.