Astronomical Cyclicity in Loess Magnetic Proxy Records From Western Arid Central Asia During the Early Pleistocene
2025-06-05 GEOPHYSICAL RESEARCH LETTERS 2025 52(卷), 11(期), (null页)
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Earth's orbital precession is expected to have a sustained impact on global climate. However, existing sedimentary records from the westerlies-influenced arid Central Asia (ACA) during the early Pleistocene are dominated by similar to 41-kyr obliquity cycles. Here, we present the first clear evidence of dominant similar to 21-kyr precession cycles in terrestrial climate proxy records from ACA during this period. We show that the ratio of anhysteretic remanent magnetization susceptibility (chi ARM) to low-frequency magnetic susceptibility (chi lf) in loess sediments is a robust proxy for paleoprecipitation. A similar to 600 ka chi ARM/chi lf record from loess deposits in western ACA exhibits clear similar to 21-kyr cycles between similar to 2.24 and 2.05 Ma, when the regional climate was dry and the pedogenic intensity was weak. These findings shed new light on the role of precession in driving hydroclimate variability and underscore the importance of low-latitude insolation forcing across the mid-latitude arid regions of Asia.
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