关键词: 柴达木盆地, 侏罗纪, 古气候变化, 化学风化指数

Abstract: A series of distinct tectonic-climatic-environmental coupling evolution events were recorded in terrestrial sequences of the
Qaidam Basin during the Jurassic. However, little research has focused on the paleoclimate and paleoweathering variation process of
these sequences. To reconstruct the Jurassic paleoclimate and paleoenvironment of the Qaidam Basin, major and trace elemental
analyses were carried out on the bulk-rock samples that were collected from the Dameigou section, which is a Jurassic standard section
located in the northern basin margin. The reconstruction mainly utilized various chemical weathering indices, including Rb/Sr, K/Na,
CIA and CIW. Results indicated that the Jurassic chemical weathering process and paleoclimate evolution of the Qaidam Basin can be
divided into four stages. During the early to middle episode of the Early Jurassic and middle episode of the Middle Jurassic, intense
chemical weathering occurred in the Qaidam Basin, indicating a temperate-subtropical warm and humid climate. During the late Early
Jurassic to Late Jurassic, due to the decrease of the regional precipitation, the chemical weathering of the basin was significantly
reduced, and the climate was semi-arid or arid. These geochemical analyses are in agreement with previous results on climate-sensitive
sediments and palaeobotany. This investigation will provide complete and continuous geochemical evidence for the change of Jurassic
paleoclimate in the Qaidam Basin and adjacent regions.

Key words: Qaidam Basin, Jurassic, palaeoclimate evolution, chemical weathering index