Phanerozoic orbital-scale glacio-eustatic variability

Abstract

Global Mean Sea Level, or eustasy, has a strong effect on depositional systems, biogeochemical cycles, and climate along continental margins. Long-term Phanerozoic Tectono-Glacio-Eustatic curves based on isotope geochemistry or plate reconstructions provide first-order trends but cannot resolve short-term (<1 Myr) high amplitude ice volume-forced variability, that resulted in glacio-eustatic fluctuations of >100 m during Paleozoic and Cenozoic icehouse times. These glacio-eustatic fluctuations were minor (∼20 – 40 m) to absent during Mesozoic greenhouse climates. We provide a continuous quantification of maximum amplitude short-term sea level change during the last 540 million years. We utilize a high-resolution Cenozoic climate model to estimate orbital-scale (10³-10⁵ years) temperature and ice volume variations as a function of long-term (≥ 1 Myr) changes in ice volume. Building upon a recent long-term ice volume reconstruction, we then calculate maximum feasible orbital-scale cyclicity for the entire Phanerozoic. Our estimates of sea level change during greenhouse climates are much lower than some estimates based on stratigraphically derived eustatic reconstructions. This suggests that these stratigraphic methods overestimate orbital-scale sea level change or that these were caused by other factors such as aquifer eustasy. Our analysis quantifies the range of glacio-eustatic sea level variability that may be used as independent constraint in future paleoclimatologic, paleogeographic, paleontologic, and paleoceanographic research.