IDYST - ISTE Seminar The seminar will take place in the AULA of the IDHEAP building and online (https://unil.zoom.us/j/3447728838). An apéro will follow on the fourth floor of the Géopolis building.
The chemistry and isotope composition of the ocean are controlled by the global budgets of the input and output fluxes of elements and their isotopes. These fluxes, in turn, are controlled by fundamental Earth-system processes, such as weathering of the continental crust, hydrothermal reactions with the oceanic crust, controlled by volcanism at mid-ocean ridges, and sedimentary processes. Thus, if we can use the sedimentary record to reconstruct the chemical and isotope evolution of seawater, we will be able to better understand the global evolution of the Earth’s surface environment. In this seminar, I will focus on the oceanic budget of magnesium (Mg). First, I will try to demonstrate how we can use magnesium isotopes (δ26Mg) to constrain its oceanic budget, with an example from the past ca. 20 Myr. Then, I will present two case studies of using dolomite as an archive for past seawater Mg isotope composition: a study of modern dolomite from a sabkha environment in Qatar, and some new Mg isotope data from Triassic dolomites (the Lombardian Alps, Southern Switzerland).
REFERENCES
Shalev N., Bontognali T.R.R., Wheat C.G. and Vance D. (2019), New isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation. Nature Communications, 10, 5646, https://doi.org/10.1038/s41467-019-13514-6.
Shalev N., Bontognali T.R.R. and Vance D. (2021), Sabkha Dolomite as an Archive for the Magnesium Isotope Composition of Seawater. Geology, 49 (3), 253–257, https://doi.org/10.1130/G47973.1.