Title: The evolution of Earth's ocean as seen by H and O isotopes

Speaker: Dr. Julien Foriel (ELSI)

Abstract:

Liquid water was present on Earth by at 4.3Ga and by 3.8Ga the first sediments suggest an ocean existed. Besides this, we know very little about the ocean in the deep past of the Earth. The precise origin of Earth's water, the size, composition and temperature of the ocean through geological times are all poorly known.

The geological record holds clues about the ancient ocean as some of its properties can be inferred from rocks altered by seawater. I will present ongoing efforts using hydrogen and oxygen isotopes to help resolve the size and temperature of the ocean.

Hydrogen isotopes can be used to track and understand the evolution of the water cycle. In collaboration with ELSI colleagues, we are trying to combine isotopic data and numerical modeling to constraint the influence of the geological cycling and atmospheric process on the size of the ocean.

For oxygen isotopes, experimental development, needed to obtain reliable analysis from silicates, will be presented. The goal of this study is to define the oxygen isotope composition of the ocean, which is necessary to infer its temperature.