Triple Oxygen Fingerprinting of Ice Sheets

Objetivo

Past glaciations profoundly shaped Earth's climate and surface systems throughout geologic time. However, our understanding of ice sheet responses to orbital forcing, greenhouse gases and tectonics is severely limited by the lack of a clear, robust, and widely applicable method for tracing oxygen-18-depleted ice in deep time (>100 ka). Reconstructing ice sheet oxygen-18, a key factor sensitive to hydrology, climate, and the geometry of ice sheets (extent, continentality, altitude), would provide unprecedented insights into the Earth's history.

I propose to fill this gap by establishing clumped + triple oxygen isotopes in marine carbonates as a widely applicable tracer of meltwater oxygen-18 and ice sheet dynamics. I will create a one-of-a-kind analytical facility with cutting-edge spectroscopic techniques and calibrate this new tracer on modern carbonates and waters, then apply it to well-preserved micro- and macrofossils (foraminifera, bivalves, ammonites...) to detect and characterize ice sheets of Pleistocene to Late Paleozoic ages. This will yield key insights into (a) oxygen-18 ratios in now-extinct Pleistocene ice sheets; (b) Pleistocene megaflood events linked to European glacial dynamics; (c) Antarctic ice inception, dynamics and composition in the Cenozoic, with major implications for interpreting benthic carbonate oxygen-18 records; (d) highly debated glaciations in the greenhouse Mesozoic era; (e) the paleo-latitudinal isotopic gradient of Late Paleozoic ice sheets. Numerical models will link these local seawater reconstructions to meltwater sources and volumes.

My research will challenge canonical assumptions of constant seawater oxygen-18 during allegedly ice-free periods, reveal ice sheet dynamics over short & long timescales and open new research frontiers in Earth system science. The spectroscopic tools developed here will bring about a technical revolution in the isotopic analysis of CO2 and other gases, with broad multidisciplinary applications.