利用活塞采样器在位于青藏高原西南部塔若错60m水深处获得3．1m沉积岩芯．通过AMS14^C测年、花粉、粒度和无机碳分析，恢复了青藏高原西南部全新世以来的植被和气候变化．结果显示，全新世初期（10200～8900 cal a BP），植被由高寒草原向高寒草甸转换，气候由冷干向暖湿发展：全新世早期（8900～7400 cal a BP），植被由高寒草甸到高寒草原的转换，气候相对干旱，但偏暖：全新世中期（7400～3300cal a BP），植被从高寒草原向高寒草甸或草甸化草原转换，气候以冷湿为主：全新世晚期（3300c ala BP至今），植被逐渐被高寒草原取代，气候变得寒冷干旱．塔若错全新世早期和中晚期的特征气候事件表明，该地区明显受到西风区环境变化的影响，而在全新世中期更多受印度季风环流控制．尤其是中晚全新世塔若错的湖泊沉积环境记录对于进一步阐述西风／季风在该地区的影响程度具有非常重要的意义．
Spores of ferns and allied plants, and micro-algae frequently occur in abundance in Quaternary deposits, but their palaeoenvironmental significance is seldom evaluated. This paper presents morphological descriptions of spores of Selaginella sinensis (Desv.) Spring, 1843 (Selaginellaceae) and Ceratopteris cf. thalictroides (L.) Brongniart, 1821 (Parkeriaceae) and the algae Pediastrum boryanum (Turpin) Meneghini, 1840, P. simplex Meyen, 1829, P. integrum N geli, 1849 (all Hydrodictyaceae), Spiniferites Mantell, 1850, emend. Sarjeant, 1970 (Spiniferitaceae) and Concentricystes Rossignal, 1962, emend. Jiabo, 1978 (systematic position unclear), and discusses their occurrence in mostly Quaternary sedimentary successions. All are closely associated with aquatic habitats. Extant Selaginella sinensis often colonizes fairly wet hillsides and gaps between rocks, and shady sides of ravines and slopes; it is also found within thickets of trees and shrubs (boscages) and in forests with calcareous soils. Ceratopteris thalictroides, Pediastrum and Concentricystes inhabit freshwater lakes and both natural and artificial wetlands, such as paddy fields and ditches. Spiniferites is a salt-water genus and usually associated with the marine realm. Fossil and subfossil representatives of all of these taxa can be useful proxies of biodiversity and, therefore, also important for determining environmental conditions during the Quaternary period.
TANG LingYuMAO LiMiLü XinMiaoMA QingFengZHOU ZhongZeYANG ChunLeiKONG ZhaoChenBATTEN David J
A 310-cm-long sediment core,covering the last10,200 years,was collected from Taro Co on the southwestern Tibetan Plateau and analyzed for pollen,grain size and total inorganic carbon content.The pollen data showed that vegetation changed from alpine steppe to alpine meadow during 10,200–8,900 cal a BP,to alpine steppe dominated by Artemisia during 8,900–7,400 cal a BP,to alpine meadow during 7,400–3,300 cal a BP and to alpine steppe after 3,300 cal a BP.Correspondingly,the pollen,grain size and total inorganic carbon content results revealed climatic change in this area over four stages.The initial stage was from 10,200 to 8,900 cal a BP,during which the climate changed from cold-dry to warm-humid.The second stage(8,900–7,400 cal a BP)was characterized by a warm and dry climate.However,at approximately7,400 cal a BP,the climate began to become cold and humid,which continued until 3,300 cal a BP.The last stage,from 3,300 cal a BP to present,was characterized as cold and increasingly arid.Climatic events of the early and mid-late Holocene showed that the area was significantly affected by the westerlies.However,the mid-Holocene climate in Taro Co was controlled by the Indian monsoon.The mid-late Holocene depositional environment record of Taro Co was very important to further elaborate the degree of influence by the westerlies or Indian monsoon.
