青藏高原东部末次冰期最盛期气候的花粉证据  

Pollen Evidence of Climate During the Last Glacial Maximum in Eastern Tibetan Plateau

作　　者：唐领余[1,2,3] 沈才明 孔昭宸[1,2,3] 王富葆[1,2,3] 廖淦标[1,2,3] 

机构地区：[1]中国科学院南京地质古生物研究所 [2]中国科学院植物研究所 [3]南京大学

出　　处：《冰川冻土》1998年第2期133-140,共8页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金

摘　　要：青藏高原许多湖泊钻孔、泥炭剖面等所揭示的花粉记录为重建当时的古气候提供了可靠的证据．应用这些资料探讨青藏高原东部末次最大盛冰期植被和气候．大约２５～１５ｋａＢＰ前后西藏东南部、川西若尔盖及青海柴达木和可可西里地区，气候寒冷干燥，年均气温比现今低６℃左右，植被以荒漠草原为主；在青海湖地区森林退缩演变为草原植被；甘肃临夏气候冷湿，年均温比现在低５～６℃。The Last Glacial Maximum (LGM) covered a time interval from 25 000 to 15 000 a BP, when the climate was cold and dry, and the Paleovegetation was dominantly dry grasslands or grassland-deserts in the Tibetan Plateau. Despite a large amount of late Quaternary palynology data published in China, there is very limited information available about pollen and vegetation during the LGM , largely because of the scarcity of fossil pollen in sediments at that stage. Only some recent studies have provided detailed palynological data for reconstructing paleovegetation during the LGM, and the pollen diagram from Lake Ren Co in Basu County , eastern Tibet, is one of them. Lake Ren Co (30°43 097′N, 96°40 052′E, 4 450 m a.s.l) is a closed-basin of freshweter lake situated in the subalpine forest-meadow region in the eastern Tibet. Surface pollen samples from the lake are dominated by Artemisia (30%) and contain about 30% tree pollen, mainly from Betula , Picea, Pinus , and Abies . A 4 m long core, predominantly consisting of gyttja, yields two basal dates of 18 250±1 030 and 17 860±340 a BP, although dating control may be complicated by hardwater effect as suggested by a date of 2 090±60 a BP from the core top. The late-glacial pollen assemblages are dominated by Chenopodiaceae (20%～50%) and Artemisia (10～30), and pollen influx values are very low. Betula pollen increased sharply after ca. 13 5ka (unadjusted data), as did Abies and Picea during the early Holocene. The data also suggest that the climate in the eastern Tibet was cold and dry during the LGM and last-glacial time. The mean annual temprature was probably 6 K colder than the present, and the mean annual precipitation was only 250 mm , about 40% of that at present. The vegetation around Lake Ren Co was probably a desert-steppe during the LGM. Similar variations can be seen in the pollen diagrams from the Wasong section and the RM core, Zoige basin, western Sichuan Province, the Gounong Co, the Qinghai lake and the Chaerhan

关 键 词：青藏高原 末次冰期 盛期气候 花粉 古气候 植被 

分 类 号：P532[天文地球—古生物学与地层学] Q913.846.3[天文地球—地质学]