Thèmes de Recherche :
Probing the geochemistry of ancient oceans with Banded Iron Formations
I am interested in the size of emerged continental surfaces from the early Archean to the late Proterozoic and to a lesser extent in their composition.
The sedimentary samples I analyze are 3.8 Ga to 0.7 Ga BIF (Banded Iron Formations) and their associated terrigenous-detrital rocks. Currently, the estimated ages of BIF are relatively poorly defined, especially those around the GOE~2.5 Ga (Great Oxygenation Event). Indeed, the ages of these deposits are determined indirectly by dating the deposits surrounding the BIF (U-Pb on Zircons). It is necessary to determine a precise age of the BIF in order to calculate the initial Nd-Hf isotopic compositions during the formation of BIF. This dating will be done via the father-son radioactive couple of Lu-Hf on the different bands (Si-rich, Fe-rich). This procedure has been studied by Garçon et al, 2017b, and will be developed during this thesis.
It is shown by the work of Garçon et al. 2013 that the decoupling of Nd-Hf isotopic pairs is proportional to the length of the sedimentary transport. After dating the deposits, measuring and relating the Nd and Hf isotopic compositions of Precambrian BIF and detrital-terrigenous rocks will allow discussion of the sedimentary fractionation processes responsible for the decoupling and consequently the dimensions of the emerged continental surfaces through time.
Tools: Clean Room, ICP-OES, ICPMS 7500Agilent, MC-ICPMS Neptune, TIMS Triton
Geochemistry: Major Elements, Trace Elements, Nd et Hf Isotopic Compositions
PhD supervisors: Marion garçon and Nicolas Olivier
PhD referrer: Philippe Labazuy
Responsabilités scientifiques et administratives :
Activités d’enseignement :
Rang A :
Rang B et C :