Tectonic-astronomical interactions in shaping late Paleozoic climate and organic carbon burial.

Tectonic processes and astronomical cycles are key drivers of Earth's climate and carbon systems. However, their interplay in shaping late Paleozoic climate variability remains poorly constrained. Here, we divide the late Paleozoic (~360-250 Ma) into three distinct tectonic phases based on full-plate tectonic reconstructions, geochemical datasets, and carbon cycle modeling, thereby elucidating how global sea levels and organic carbon burial responded to astronomically forced climate fluctuations under different tectonic phases. Our results show that intervals spanning ~360-330 Ma and ~280-250 Ma were characterized by elevated atmospheric CO2 levels and intensified tectonic activity, which coincided with heightened climate variability and reduced regularity in orbitally paced sea-level changes. In contrast, during ~330-280 Ma, multiple proxies indicate reduced tectonic forcing and lower CO2 concentrations, which were accompanied by more stable climate conditions and clearer expression of astronomical cycles. These conditions facilitated rhythmic deposition and widespread organic carbon burial.