Breaking the Limitations of Traditional Cyclostratigraphy: Application of AstroGeoFit in High-precision Mesozoic Dating

Accurate geological chronology serves as the core foundation for decoding the evolutionary history of the Earth, and obtaining high-precision, highly reliable geological time scales has long been a highly challenging scientific issue in the field of geosciences. Compared to biostratigraphy, magnetostratigraphy, and radioisotopic dating, astrochronology offers the advantage of continuous high-resolution dating but faces inherent limitations. Traditional orbital tuning often assumes stable or constant sedimentation rates within studied intervals. This assumption overlooks the dynamic nature of sedimentation, introducing significant subjectivity and leading to divergent results among different researchers. To address these issues, this study use AstroGeoFit, which utilizes genetic algorithms to establish age-depth functions in stratigraphic records with variable sedimentation rates. An absolute astronomical timescale can be constructed by extracting key astronomical signals from paleoclimate proxies and matching them to theoretical astronomical solutions. Here we analyzed three Mesozoic records as examples: (1) Early-Middle Triassic Successions (South China): analysis of natural gamma ray series from the semi-deep-marine Xiakou (130 m) and shallow-marine Guandao (260 m) sections yields durations of 6.512 +0.446/-0.219 Myr and 6.011 +0.136/-0.091 Myr, respectively. Correlation with the ZB18a solution established a continuous absolute timescale from 240.489 Ma to 252.325 Ma. The calibrated boundary ages for the PTB (252 Ma), I/O (250.4 Ma), O/A (246.3 Ma), and A/L (241.5 Ma) are consistent with the previous results by traditional cyclostratigraphy combined with magnetostratigraphy. (2) Continental Newark Basin (USA): analysis of the approximately 3448 m-long Depthrank series yields a duration of 22.880 Myr, which is about 1.4 Myr longer than the traditional cyclostratigraphic result (21.465 Myr). Comparison with La2010 and ZB18a solutions yielded absolute timescales (starting 201.875 Ma and 200.971 Ma, respectively) that align closely with previous calibrated by traditional cyclostratigraphy-magnetostratigraphy framework. (3) Deep-marine Piobbico Core (Italy): analysis of the about 77 m long grayscale series yields a duration of 22.399 Myr, which is 3.2 Myr shorter than the prior tuning results. An absolute timescale from 101.008 Ma to 123.407 Ma was established via correlation with the La2010a solution. This study demonstrates that AstroGeoFit can effectively decouple astronomical signals from non-stationary sedimentary noise, providing a more objective and statistically robust framework for geochronology. By successfully reconciling records across diverse sedimentary facies (deep-marine, shallow-marine, and continental), this research provides a quantitative pathway for refining the Mesozoic Geological Time Scale.