Sunspot Research Journal Article

This study explored the under-recognized global impact of the 11-year sunspot cycle on thinly laminated strata, using the Middle Jurassic Hulett Member of the Sundance Formation in Wyoming, USA. At this site, a 4-meter deposit of thin micrite and silt-sized quartz couplets was found in a hyperarid restricted lagoon. Fast Fourier transform analyses showed an 11-year periodicity in lamination thickness matching the sunspot cycles, and almost every eleventh couplet displaying lamination thickness variation likely caused by annual sunspot cycle impacts. Despite potential deviations from local climate variability, erosion, or non-cyclical deposition, a minimum of 7,000 years was estimated for the Jurassic lagoon infilling, indicating rapid deposition and significant sunspot-influenced climate signals. The study highlighted the importance of solar cycles on depositional periodicity and their role in understanding paleoclimate dynamics.