13.5~2.5 Ma索尔库里盆地沉积物碳氧同位素对古气候演化的记录

索尔库里盆地位于青藏高原东北缘,柴达木盆地的北部,气候恶劣、交通不便,研究资料匮乏。通过对索尔库里北盆地彩虹沟剖面新近纪中后期沉积物的古地磁测年和碳酸盐碳氧同位素质谱分析,揭示了索尔库里盆地13.5~2.5 Ma长序列气候演变过程。13.5~9.2 Ma时期相对冷干,9.2~5.3 Ma时期相对温湿,5.3~3.9 Ma时期相对暖湿,3.9~2.5 Ma时期再次转为冷干。11 Ma左右,青藏高原东北缘隆升到阻止印度洋暖湿气流向北方运输的高度,地处走滑盆地的索尔库里地区逐渐变得极其干旱,标志着亚洲内陆干旱化在此背景下开始。红粘土磁化率和碳氧同位素变化等证据显示,西风在本区贯穿始终,而季风的出现加剧了亚洲内陆古气候的干湿更迭,对区域及全球古气候重建具有重要意义。

A Study on Paleoclimatic Evolution of the Xorkol Basin during 13.5 to 2.5 Ma by Using Carbon and Oxygen Isotopes of Sediments

The Xorkol Basin is located in the northeast margin of the Tibetan Plateau, and the north of the Qaidam Basin, China. Bad weather and traffic inconvenience cause lacking of the research data for this area. In this study, carbon and oxygen isotopes of the sediments in Caihonggou section of the Xorkol Basin were obtained and paleomagnetic dating and mass spectral analysis were conducted. The climate evolution of the Xorkol Basin during long sequence of 13.5-2.5 Ma was revealed. During the period of 13.5-9.2 Ma, the climate had been relatively cold and dry; during 9.2-5.3 Ma, it had been relatively warm and humid; during the period of 5.3-3.9 Ma, it had been relatively warm and rainy; during the period of 3.9-2.5 Ma, it had turned back to cold and dry. At about 11 Ma, the northeastern margin of the Tibet Plateau uplifted and prevented transporting India Ocean warm moisture to north. The Xorkol Basin located near strike-slip fault was becoming extremely arid and marked the beginning of the Asian inland''s drought in this context. The results show that the westerly winds continue throughout the region; the emergence and development of the monsoon intensifies the dry and wet changes of paleoclimate in Central Asia, which is of great significance to the regional and global paleoclimate reconstruction, through the evidence of the magnetic susceptibility of red clay and carbon and oxygen isotopes variation tendency.