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IX
Final
discussion and conclusions
This PhD mainly deals with the study of the
HP–HT Banded Gneiss formation of the Upper
Allochthon of the Cabo Ortegal Complex. When
the metasedimentary rocks from this formation
were investigated, the overlapping IP Cariño
Gneisses were also taken into account and when
the Banded Gneiss igneous rocks were studied
the underlying Eclogite Band formation was
also investigated. The general discussion and
conclusions of all this work are summarised as
follows.
The Banded Gneiss and Cariño Gneiss
formations have a very similar old detrital
spectrum (> 1 Ga) and therefore their detrital
provenance will be discussed together. The main
Archean population is interpreted as a
c.
2.70 Ga
intrusion of juvenile magmas into an older crust
triggering limited mixing processes (Fig. 1).
From intrusion at
c.
2.70 Ga to
c.
2.40 Ga it seems
that this population registers a long lasting crust
reworking process and probably other intrusion
events at around 2.51 Ga, or Pb-loss processes
triggered by high-grade metamorphic events.
This Archean population also shows an intrusion
at
c.
3.0 Ga and a reworking process. The
provenance of this population has been assigned
to the Western Reguibat Rise, in the West Africa