[ES_JOBS_NET] PhD Opportunity in Isotope Geochemistry at the University of Strasbourg

[Erika Marín-Spiotta]

"PhD Opportunity in Isotope Geochemistry at the University of Strasbourg –
"Characterization and modeling of sediment transport in the alluvial plains
coupling U- and Th-series disequilibria with B and Li stable isotopes"" has
been updated by Damien Lemarchand on CZEN.org.

The
sediments carried by rivers keep the memory of their origin and the
physico-chemical
transformations resulting from the weathering reactions. However, using
sedimentary records to reconstruct weathering conditions first requires a
precise understanding of the mechanisms and parameters that control the
geochemical
signal recorded by sediments. In particular, it is critical to determine to
what
extent the geochemical variations measured in suspended sediments in rivers
or
deposited in floodplains are linked to changes in weathering conditions or
to
physico-chemical transformations occurring during transport and/or after
their
deposit. For this, a key point is to determine the timing of the production
and
transport of the sediments from the headwaters were there are produced to
the
floodplain where they are stored.

The thesis
project proposes to evaluate the potential of a study coupling
geochronometric
methods using the U- and Th-nuclides series (radioactive disequilibrium) and
the analysis of “non-traditional” B and Li stable isotopes that give new
information on the mechanisms underlying the formation and transformation of
sediments in alluvial basins. These isotopic tools will be applied to the
study
of sediments from “model” rivers, including watersheds and alluvial
basins already
well studied. The objectives are: 1) using isotopic tools to trace the
processes
controlling the formation and transport of sediments in alluvial basins from
the
headwaters to the flood plains, and 2) to provide time constraints on these
processes and focus especially on their response to changes in environmental
conditions such as climate, agriculture, urbanization, and land use changes.

This is a
prospective study, which will give a spatio-temporal framework of the
processes
controlling the production and transport of the sediments at the scale of an
alluvial system. This relationship between the weathering processes and
their
response to forcing parameters is still difficult to define even though it
is
essential to understand the role of sediment transfer in surface geochemical
cycles.

The PhD project will be undertaken under the supervision of D. Lemarchand
and
F. Chabaux at the University of Strasbourg

project starts Oct. 2015

The applicant should have a M.Sc. or equivalent, some knowledge of isotope
geochemistry, chemical weathering. Experience in a clean lab and mass
spectrometry will be appreciated

Salary will be equivalent to the standard French Postgraduate Award stipend:
∼16,500€

If interested, send a cover letter and CV to Damien Lemarchand
(lemarcha at unistra.fr [1]) and François Chabaux (fchabaux at unistra.fr [2])

Deadline for applications (flexible) is 15 July 2015.
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