Project CruRec – Unlocking and using the potential of Mo stable isotopes as a tracer of crustal recycling

Basic data

Acronym:
CruRec
Title:
Unlocking and using the potential of Mo stable isotopes as a tracer of crustal recycling
Duration:
01/02/2019 to 01/02/2022
Abstract / short description:
The origin of the heterogeneous trace element and radiogenic isotopic
compositions of the Earth’s mantle observed through oceanic basalts
has been an active question for the last three decades. The return of
crust back to the mantle has long been suggested to be responsible
for the dominant heterogeneities observed. However, processes such
as intra-mantle metasomatism were also proposed to partly or entirely
explain the observed variations without crust involvement. Already in
the 80s, stable isotope investigations of oceanic basalts were
suggested to have the potential to close this debate. This is because
the largest stable isotope fractionations occur at low temperature, i.e.,
at the surface of the Earth. Hence the presence of strongly
fractionated signatures in oceanic basalts was expected to be the
unambiguous proof of recycled crust back to the mantle. However, the
interpretation of stable isotopes revealed more complex than initially
predicted, with large isotope fractionation found to occur during high
temperature processes such as partial melting, magma differentiation
and slab dehydration/melting at subduction zones. For most stable
isotopic systems, the lack of a full understanding of the behaviour of
stable isotopes during these processes precludes convincing
evidence and characterization of recycled crust in the source of
oceanic basalts. This proposal aims at unlocking and subsequently
using the potential of Mo stable isotopes as a powerful tracer of
crustal recycling. The Mo stable isotopic system is a very promising
tracer but its full potential is currently hampered by the lack of
constraints on Mo stable isotope behaviour during (1) island arc and
continental crust differentiation; (2) slab metasediment and
metabasite melting at subduction zones and (3) the production and
differentiation of low-degree mantle partial melts. The goal is to fill
these knowledge gaps on the high temperature behaviour of Mo
isotopes and to investigate and characterize recycled crust in the
source of oceanic basalts covering the whole compositional spectrum
defined by radiogenic isotopes.
Keywords:
Mo isotopes
crustal recycling
mantle reservoirs

Staff

Managers

Faculty of Science
University of Tübingen
Mineralogy and Geodynamics Research Area
Department of Geoscience, Faculty of Science

Local organizational units

Mineralogy and Geodynamics Research Area
Department of Geoscience
Faculty of Science

Funders

Bonn, Nordrhein-Westfalen, Germany
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