摘要：

吐鲁番盆地是天山山脉中的一个山间盆地，古近系保存完好，是研究中国西北地区古近纪气候变迁的良好地区。通过对吐鲁番盆地连木沁剖面古近系多种气候代用指标（Fe₂O₃、FeO、CaCO₃、有机碳、有机碳同位素）的研究，探讨了吐鲁番盆地古近纪的气候变迁和重要气候事件。利用Fe3+/Fe2+值，恢复了吐鲁番盆地古近纪的气温：古新世的年均气温为22.35℃，始新世为21.82℃，渐新世为15.69℃，并且在渐新世的早期和晚期发生较大幅度的降温事件。对地层中CaCO3（碳酸钙）含量的研究表明，古新统和始新统碳酸钙平均含量分别为468％和666％，指示该沉积时期气候相对比较湿润，而渐新统达15.01％，指示渐新世气候明显干旱化，并且渐新世的早期和晚期气候更为干旱。有机碳同位素（δ¹³Corg）值分布于C3植物的范围内，表明其受C3植物的影响。对地层中的δ¹³Corg值研究显示，该值与地层中碳酸钙含量呈负相关，与气温呈正相关，即该值偏负时，地层中碳酸钙含量增加，气温降低。各种气候指标指示吐鲁番盆地古新世和始新世气候比较温暖湿润，而渐新世气候干旱温凉。

Abstract:

The Turpan Basin is an intermountain basin in the Tianshan Mountains. A good preservation of the Paleogene in this basin provides abundant information for studying of the Paleogene climate in  Northwest China. Based on various climatic proxies from a section at Lamjin in the Turpan Basin， such as Fe₂O₃， FeO， CaCO₃， organic carbon and organic carbon stable isotopes， this paper focuses on climatic changes and key climatic events during the Paleogene. Temperatures of the Paleogene in the Turpan Basin are estimated by the ratios of Fe₃+/Fe₂+. Annual mean temperatures were 22.35℃ in the Paleocene， 21.82℃ in the Eocene and 15.69℃ in the Oligocene respectively. A key temperaturefalling event took place during the transitional period from the Late Eocene to the Early Oligocene. Researches on CaCO₃ content of the Paleogene indicate that the mean content of CaCO₃ was 4.68％ in the Paleocene and 6.66％ in the Eocene respectively， while the mean content of CaCO₃ reached 15.01％ in the Oligocene. These data show that the climates in the Paleocene and Eocene were relatively humid， while arid in the Oligocene. Values of organic carbon stable isotopes(δ¹³Corg)from the Paleogene sediments concentrate in the scope of the C3 plants， which indicates C3 plants were  developed in the Turpan Basin at that time， and δ¹³Corg values have a negative relationship with CaCO₃ content but a positive relationship  with temperatures. Namely， a decrease of the δ¹³Corg value corresponds to an increase of the CaCO3 content and a fall of the temperature. The various climatic proxies indicate that the climate was relatively warm and humid in the Paleocene and Eocene， while arid and cool in the Oligocene.