From Jurassic deep-sea life to deterministic Solar System dynamics: insights from recurrence plot analysis of ichnological data, Toarcian, Llanbedr (Mochras Farm) borehole, UK

Bioturbation structures preserved in the c. 260 m long Toarcian section of the Llanbedr (Mochras Farm) borehole (Wales, UK) display cyclic occurrences influenced by astronomical forcing. Depth-domain data series of ichnotaxa distribution were analysed using recurrence plots, which allow observation of cyclic patterns across various scales simultaneously and assessment of the varied responses of different tracemakers to the influence of particular orbital terms. Phycosiphon and Schaubcylindrichnus occurrences reflect the combined effect of precession, obliquity, and short eccentricity. In turn, conditions favouring the development of undulated bedding and the Thalassinoides and Trichichnus tracemakers were primarily controlled by the long eccentricity. Disruptions in the plots likely result from average sedimentation rate changes, and stress conditions experienced by benthic fauna during the latter stages of the Early Toarcian carbon isotope excursion. Generally, the plots reveal patterns characteristic of systems governed by deterministic chaos, with pronounced cyclic components.