A 94–10 ka pollen record of vegetation change in Qaidam Basin, northeastern Tibetan Plateau
A 94–10 ka pollen record of vegetation change in Qaidam Basin, northeastern Tibetan Plateau
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DOI：
10.1016/j.palaeo.2015.04.025
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
Hai-cheng Wei;Qi-shun Fan;Yan Zhao;Haizhou Ma;Shan Fashou;Fuyuan An;Q. Yuan
中科院分区：
文献类型：
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作者：
Hai-cheng Wei;Qi-shun Fan;Yan Zhao;Haizhou Ma;Shan Fashou;Fuyuan An;Q. Yuan
钻芯(ISL1a)取自青藏高原东北部柴达木盆地中东部察尔汗盐湖。结合AMS14C和230Th测年，分析了化石花粉和岩心沉积物的岩性。结果表明，94~51.2年间，草原/荒漠草原植被以蒿属和藜科植物为主，与柱状沉积物中沉积的富含有机质的粉质粘土相对应；94~51.2年间，古察尔汗湖沉积物中不断出现泥炭，表明古察尔汗湖在海相同位素阶段(MIS5)晚期、MIS4期和MIS3早期处于淡水-低盐化状态；51.2~32.5Ka期间，盆地以麻黄为主的灌丛荒漠植被扩张，泥炭消失。在51.2至32.5年间，岩芯沉积物由盐岩粉砂和富含粘土的盐岩互层组成，意味着向更干燥的水文条件转变。32.5~25.3年间，古察尔汗湖再次出现以蒿科和藜科为主的草原/荒漠草原植被，并以富含粘土的沉积物为核心，表明在相对湿润的气候条件下，湖泊径流增加。然而，自25.3年后，花粉浓度下降，与沉积在岩芯沉积物中的岩盐数量相对应，这表明在MIS2期间气候条件寒冷、干燥。我们的发现对于了解柴达木盆地复杂的区域植被和气候对大规模强迫的响应具有重要意义。
Drill core (ISL1A) was obtained from the Qarhan Salt Lake in central eastern Qaidam Basin, northeastern Tibetan Plateau (NE TP). Fossil pollen and the lithology of the core sediment were analyzed in conjunction with AMS14C and230Th dating. The results indicated thatArtemisiaand Chenopodiaceae dominated the steppe/desert steppe vegetation developed around the lake between 94 and 51.2 ka, corresponding with the organic-rich silty clay deposited in the core sediments.Pediastrumcontinuously appeared in the core sediments between 94 and 51.2 ka, indicating freshwater to oligohaline conditions of the paleo-Qarhan Lake during the late marine isotope stage (MIS) 5, MIS 4, and early MIS 3. During the 51.2 to 32.5 ka period,Ephedradominated shrub-desert vegetation expanded in the basin, while,Pediastrumdisappeared in the core sediments. The core sediments consisted of interbedded layers of halite silt and clay-rich halite between 51.2 and 32.5 ka, signifying a shift toward drier hydrologic conditions. Thus, the paleo-Qarhan Lake experienced periods of desiccation and shallow water levels.Artemisiaand Chenopodiaceae dominated steppe/desert steppe vegetation appeared again from 32.5 to 25.3 ka, with clay-rich sediments in the core, thereby suggesting an increase of runoff from the lake under relatively wetter climatic conditions. Since 25.3 ka, however, pollen concentrations declined, corresponding with the amount of halite deposited in the core sediment and, suggesting a cold, dry climatic condition during MIS2. Our findings have important implications for understanding complex regional vegetation and climatic responses to large-scale forcings in the Qaidam Basin.