Integrated stratigraphy of the Ludlow (Silurian) of the Baubliai-2 core (western Lithuania) and the record of δ18O and δ13C climatically driven co-variability

Ludlow Epoch of the Silurian Period is a key point in understanding evolution of marine biota and large scale climate perturbations. Here we present an integrated record of graptolites, delta C-13, and delta O-18 of carbonates from a deep shelf section of the south-eastern part of the Silurian Baltic Basin. Graptolite record allows us to distinguish ludensis (?), nilssoni, scanicus, leintwardinensis and tenuis graptolite biozones, and the delta C-13 trend shows ascending portion of the mid-Ludfordian excursion. In addition we investigated the time specific variability in delta C-13, and delta O-18 and their interaction. Cross-correlation analysis revealed a significant interaction between these variables, where delta O-18 driven delta C-13. Spectral and recurrence quantification analyses revealed that the variability in delta O-18 is characterized by a very distinct periodicity with period length of approximately 1 Myr, which putatively interpreted here as representing climatic signal of long-period amplitude modulation of obliquity. The presented data confirm the importance of grand Milankovitch cycles in the pacing of geobiological change during the late Silurian.

Automated summary

The Ludlow Epoch of the Silurian Period is crucial for understanding the evolution of marine biota and climate perturbations. This study presents an integrated record of graptolites, delta C-13, and delta O-18 of carbonates from a deep shelf section in the Silurian Baltic Basin. The data reveals distinct graptolite biozones and an ascending portion of the mid-Ludfordian excursion in the delta C-13 trend. The study also explores the interaction between delta C-13 and delta O-18, with the latter driving the former. Spectral and recurrence quantification analyses suggest a climatic signal with a periodicity of approximately 1 Myr.