An astronomically calibrated stratigraphy of the Mesoproterozoic Hongshuizhuang Formation, North China: Implications for pre-Phanerozoic changes in Milankovitch orbital parameters

Abstract

This study presents a cyclostratigraphic investigation of the Mesoproterozoic Hongshuizhuang formation (about 1.45 Ga) in North China. High-resolution, continuous magnetic susceptibility and X-ray fluorescence elemental data were obtained from the YuanJi-2 drillcore. We tested the present astronomical age models using the multi-taper spectral analysis and correlation coefficient (COCO) methods from three paleoclimate proxies, i.e. magnetic susceptibility, Al and Ca elemental contents. The proxies record orbital forcing cyclicity with varying sensitivities which was attributed to their distinctive corresponded to depositional environments or diagenesis. The 405-kyr-calibrated ATS indicates the HSZ Formation has a similar to 3.1 Myr duration and an average sedimentation rate of similar to 3.94 cm/kyr. According to our results, the eccentricity at 1.45 Ga has cycle periods of similar to 405, similar to 125, similar to 115 and similar to 90 kyr. In addition, several significant cycle periods at similar to 28-20 kyr, similar to 18.2 kyr and similar to 16.3-14 kyr are regarded as the obliquity or precession cycles.