Small lakes distributed in the eastern edge of the Qinghai-Xizang plateau are less affected by human activities due to their special geographical location.Their sedimentary records have regional significance in response to climate and environmental changes,especially in restoring short-time scale climate and regional sedimentary environment.However,there are few studies involved at present.In this paper,trace element geochemical analysis was carried out on the sedimentary core samples of 45 cm in the center of Cuopu Lake in Ganzi Prefecture,Sichuan Province,and the local climate evolution process in the past 200 years was reconstructed.The results show that in recent 200 years,rare earth elements have basically the same longitudinal variation trend,and they all keep low values during the little ice age from 1841 to 1920,and reached the lowest value due to the indirect influence of the earthquake around 1890,and then increased with the warming of the climate.According to the principal component analysis of trace elements,the change of most trace elements is controlled by the erosion and weathering factors of the basin,which can reflect the strength of regional weathering;Rb,Ba,Sr are mainly controlled by humidity factor and can be used to restore the change of humidity.Combined with the change characteristics of various trace element environmental substitution indexes and sediment particle size composition,the climate and environment evolution process of Cuopu Lake from 1841 to 2017 is divided into 5 stages:cold-dry(1841-1904),mild-moist(1904-1923),mild-dry(1923-1944),warm-moist(1944-1966)and warm-dry(1967-2017).
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