CYCLO-SED

Dating of geological strata is the basis of our understanding of Earth’s history. The accurate estimation of durations of geological events is a key, long-lasting, and often elusive target for the geological community. Cyclostratigraphy has revolutionized this field of research over the last decade. The paradigm is that Earth’s orbit around the Sun exhibits cyclic variations of known periods, and because changes in the orbit impact the energy received from the Sun, they also impact the climate system and ultimately imprint the sedimentary record. The Milankovitch theory of climate proposes to explain the astronomical pacing of Earth’s climate under icehouse conditions, by ice-sheet-mediated amplifications of the orbital signal. No similar theory exists in the absence of land ice during (pre-Pleistocene) greenhouse climates, although the latter represent the bigger part of the Phanerozoic Eon. The objective of ANR project CYCLO-SED is to provide a mechanistic understanding of how changes in incoming solar radiation at the top of the atmosphere translate into variations in the chemistry of marine sediments in deep-time, non-glacial climates. Underlying processes are so far unconstrained and constitute a black box, which we intend to open during this project. I will use an innovative numerical Earth System Model, developed during the project, to approach this question in a quantitative, experimental and mechanistic manner.