The Jbel Saghro alkaline complex was emplaced close to the eastern edge
of the Moroccan Anti-Atlas. Within the northern part, two types of
nephelinite were recognized [Ibhi and Nachit, 1999 and lbhi, 2000].
The first type (olivine-rich nephelinite) constitutes the main volcanic
mass south of the Bou Gafer granit (fig. 1), where the volcanism had
been active at least during 2 Ma, between 9.6 and 7.5 +/- 0.1 Ma
[Berrahma et al., 1993]. The second group outcrops in the north (Foum
El Kouss). It consists of pyroxene nephelinites which are younger (2.9
+/- 0.1 Ma) [Berrahma et al., 1993], and bears carbonatitic xenoliths,
melteigitic pyroxenites and metasomatised peridotite xenoliths.
Geochemically, the pyroxene nephelinite is highly enriched in LILE
compared with the first one. The mineralogical and geochemical
characteristics may be explained by the incorporation of carbonatitic
and melteigitic pyroxenite segregates of carbonatitic affinity.