A novel approach for detecting astronomical forcing in paleoclimate proxies based on power ratios

Research based on cyclostratigraphic analysis is revolutionizing our understanding of paleoenvironment, paleoclimate, paleoceanography, celestial mechanics, and paleontology. However, as a key step of cyclostratigraphic analysis, detection of astronomical cycles often faces controversy in the absence of absolute age constraints. An approach is essential for extracting robust evidence of astronomical cycles from diverse geological records. The power ratio is the most direct parameter for characterizing astronomical forcing and is a key indicator of the Earth system’s response to insolation changes. This study focuses on the power ratio characteristics linked to astronomical forcing and their potential for identifying astronomical cycles. We propose a new methodological approach—the power ratio accumulation method based on multiple features (PRAMF)—to quantify astronomical forcing by integrating parameters derived from power ratio analysis. Based on five synthetic series, the effectiveness of the PRAMF method is validated, and the impacts of cutoff frequencies, the number of astronomical cycles, and noise on power ratios are systematically analyzed. To illustrate the utility of this approach, the PRAMF method is applied to three types of paleoclimate proxies from different periods: late Paleogene color data from the South Atlantic Ocean, Late Cretaceous thorium content logs from the Songliao Basin (Northeast China), and Late Triassic depth-rank series from the Newark Basin (Northeast USA). PRAMF analysis of the three real-world paleoclimate proxies corroborates existing cyclostratigraphic interpretations, providing independent validation of previous astronomical age models. Our study provides a reliable tool for quantifying astronomical forcing in paleoclimate proxies and will advance the application of cyclostratigraphy to complex geological records.