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VI
Provenance of the
HP-HT subducted margin
in the Variscan belt
6.1. Introduction
6.2. Partial Conclusions
6.3. Article
6.1. Introduction
The article presented in this chapter
deals with provenance investigations on the
metasedimentary rocks of the Banded Gneiss
formation. This terrain formed part of a passive
continental (or transitional) margin between
its genesis to the development of the Devonian
HP–HT metamorphic recrystallizations. As this
metamorphic event was driven by a subduction
process the aim of these investigations is to
identify the continent that subducted.
6.2. Partial conclusions
Data representative of the West Africa Craton
(WAC) shows similar and compatible patterns to
those shown by the HP–HT Upper Allochthon
presented herein. A similar thorough comparison
as the previous chapter has been made between
the Banded Gneisses and the WAC detrital and
igneous U–Pb zircon data, which allows to
confirm once again the WAC provenance for the
Upper Allochthon. This comparison has been
made for each of the zircon populations, but the
comparison of the Mesoproterozoic populations
deserves a special mention.
In the Mesoproterozoic Era, the WAC became
a stable craton which resulted in a characteristic