Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

In Tifinar And Tidjerazraze


Occurrence number: 
Longitude: 0.33, Latitude: 20.8

The In Tifinar and Tidjerazraze centres comprise numerous volcanic plugs with some plutonic rocks extending in a north-south line over some 30 km with to the east a northeasterly orientated dyke swarm (Liegeois et al., 1991 and J.F. Sauvage, pers. comm., 1985). The more southerly Tidjerazraze complex comprises nepheline syenites covering 12 km2 that invaded phonolites. Three phases of nepheline syenite define a concentric structure and comprise an outer sodalite-biotite-diopside-aegirine-augite-hastingsite-nepheline syenite that is separated by an arcuate intrusion of sodalite-analcime-hedenbergite-aegirine-hastingsite-arfvedsonite-nepheline syenite from a central stock of aenigmatite-arfvedsonite-aegirine-nepheline syenite. The more agpaitic nepheline syenites and their pegmatites contain eudialyte, catapleiite, wohlerite and mosandrite as important accessory minerals. The phonolites include both miaskitic and agpaitic types. No detailed information on the In Tifinar centre has been found except that it includes nepheline syenite.

Rb-Sr determinations on seven rocks yielded an isochron age of 161±5 Ma (Liegeois et al., 1991).
LIEGOIS, J.P., SAUVAGE, J.F. and BLACK, R. 1991. The Permo-Jurassic alkaline province of Tadhak, Mali: geology, geochronology and tectonic significance. Lithos, 27: 95-105.J.F. Sauvage, pers. comm. 1985).
Fig. 3_163 The distribution of alkaline intrusions in the Tadhak Province, which lies to the northwest of the Iforas intrusions. The most northwesterly of the Iforas occurrences (Tessalit, No. 10) is shown.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith