Environmental evolution of the south margin of Qaidam Basin reconstructed from the Holocene loess deposit by n-alkane and pollen records

This study provides the n-alkane and pollen records of the Holocene loess at Balong (巴隆) Town, Dulan (都兰) County, Qinghai (青海) Province, and the environmental changes reconstructed from both records agreed well. Three stages of past climate change were deciphered by variations of the n-alkane and pollen proxies. Before 5 370 a BP, the climate was warm-dry but slightly humid, corresponding to the Mid-Holocene climatic optimum; 5 370–3 830 a BP, the climate changed alternatively between warm-dry slightly humid and warm-dry, indicating the transition from the Mid-Holocene climatic optimum to the Late Holocene cold period; after 3 830 a BP, the climate was mainly warm-dry. The warm cool and extremely dry climate during 3 040–2 600 a BP was recorded by both the n-alkane and pollen proxies, suggesting the environment evolved into desert or salt lake, in accordance with the cold and highly frequent natural disaster period in the Western Zhou Dynasty (ca. 2 996–2 721 a BP) in China.