甘肃张掖白垩纪早Aptian期黑色页岩揭示的气候岁差驱动及其意义

The earth experienced profound environmental changes at the mid-Cretaceous when a typi-cal representative of the greenhouse climate occurred. In the mid-Cretaceous, studies have shown that black shale in low-latitude ( ca. 20° ~ 30° N ) marine strata in Europe records presents obliquity signals, continental deposits are prevalent in inland China at the same latitude and during the same period, but there are few studies on the orbital-scale periodicity of continental low-latitude black shales. In this study, CaCO₃ content is used as an alternative high-resolution indicator of paleoclimate, and average spectral misfit (ASM) and time scale optimization (TimeOpt) analyses are used to explore the orbital periodicity of the black shale in the Xiagou Formation of the early Aptian of Cretaceous in Nantaizi ( palaeoatitude of ca 23°N) , Zhangye of Gansu Province, China. The result shows that the climate is dominated by precession and eccentricity cycles, which is significantly different from the result in Europe. The exploration of this climate change not only provides new evidence for the cretaceous orbital-scale climate change in the Northwest China, but also contributes to a more comprehensive understanding of the driving mechanism of climate change in the mid-Cretaceous.