【摘要】：孢粉是研究古氣候、古環(huán)境演變的有效代用指標,建立表土孢粉組合與氣候之間的關系模型是定量恢復古氣候的基礎。而模型建立的關鍵是在現(xiàn)有氣象資料(溫度、降水等)基礎上,利用插值方法獲得采樣點對應的氣象數(shù)據(jù)。本研究首先對壩上地區(qū)氣象數(shù)據(jù)采用不同的插值方法進行比較,研究表明,在壩上地區(qū),協(xié)同克里金法是最佳的氣溫降水數(shù)據(jù)插值方法。運用協(xié)同克里金法根據(jù)經緯度賦值給表土花粉,建立表土孢粉與氣溫降水模型。在建立年代序列的基礎上,對壩上察汗淖爾剖面344 cm的湖泊沉積樣品進行孢粉、粒度分析,定量重建壩上全新世以來的古氣候古環(huán)境演變特征。其中,重點分析全新世階段,其余時間段則合并為一個階段進行分析。在11.73 ka B.P.~45.66 ka B.P.階段,年均溫4.80℃,年降水量為344.96 mm。在7.68 ka B.P.~11.73ka B.P.階段,年均溫和年降水量均略有上升。在6.04 ka B.P.~7.68 ka B.P階段,年均溫為4.84℃,年降水量為347.81mm。在4.12 ka B.P.~6.04 ka B.P階段,年均溫略有上升。在3.81 ka B.P.~4.16 ka B.P階段,年均溫和年降水量均繼續(xù)上升。在3.54 ka B.P.~3.81 ka B.P階段,年均溫達到最高值,年降水量也達到最高值。年均溫度為5.08℃,年降水量為354.28 mm。此后2.80 ka B.P.~3.54 ka B.P.階段,年均溫和年均降水量均呈現(xiàn)波動下降的趨勢。2.21 ka B.P.~2.73 ka B.P.階段,年均溫持續(xù)下降且年均降水量下降。從2.21 ka B.P.至今,年均溫度為4.79℃,年均降水量為348.15 mm。分析表明壩上地區(qū)全新世以來的氣候總體表現(xiàn)為溫度升高及降水增多,在全新世中期,氣溫最高和降水量最多。全新世晚期以來,該區(qū)氣候再次有溫度降低降水量減小然后又增大的變化趨勢,這與其他地區(qū)全新世以來氣候特征總體一致,但具有地區(qū)氣候演變差異的特征,其研究結果有助于了解該地區(qū)尤其北方農牧交錯帶典型氣候特征,進而為該地區(qū)環(huán)境政策的制定提供基礎資料及理論依據(jù)。
[Abstract]:Sporopollen is an effective substitute index for the study of paleoclimate and paleoenvironmental evolution, and the establishment of a relationship model between palynological assemblage and climate is the basis for quantitative restoration of paleoclimate. On the basis of the existing meteorological data (temperature, precipitation, etc.), the key to model establishment is to obtain the meteorological data corresponding to the sampling points by using interpolation method. Firstly, different interpolation methods are used to compare the meteorological data in Bashang area. The results show that the synergetic Kriging method is the best interpolation method for temperature and precipitation data in Bashang area. A model of surface soil pollen and temperature precipitation was established by using the method of synergetic Kriging to assign pollen to the surface soil according to the longitude and latitude values. Based on the time series, the paleoclimate paleoenvironmental evolution characteristics since the Holocene were quantitatively reconstructed by pollen and particle size analysis of the lake sediment samples of 344 cm in Cnnao section, Bashang. The Holocene stage is mainly analyzed, and the other time periods are merged into one stage. At 11.73 ka B.P.~45.66 ka B.P. The annual mean temperature is 4.80 鈩，

本文編號：2342684