Alkaline Rocks and Carbonatites of the World

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

Jibal Sha

stripes

Occurrence number: 
155-00-015
Country: 
Sudan
Location: 
Longitude: 35.97, Latitude: 20.35
Carbonatite: 
No

This complex forms a 10 km long 600 m high ridge formed of a series of overlapping intrusions. A contact aureole extends for 200 m into the country rock foliated granodiorite. The principal rock types are peralkaline syenites but trachyte, monzonite and microgranite are also present. Most rock types include sodic pyroxene and the intrusions become progressively richer in amphibole and quartz westwards, the final syenite being an amphibole-biotite-quartz syenite with minor aegirine. Cutting the youngest syenite and a small microgranite at the western end of the complex is a plug of trachyte breccia and feldspar porphyritic trachyte.

Age: 
Ten syenite samples gave a Rb-Sr isochron age of 135±3 Ma (Vail et al., 1984).
References: 

VAIL, J.R., ALMOND, D.C., HUGHES, D.J., KLEMENIC, P.M., POOLE, S., NOUR, S.E.M. and EMBLETON, J.C.B. 1984. Geology of the Wadi Oko-Khor Hayet area, Red Sea Hills, Sudan. Bulletin of the Geology and Mineral Resources Department, Republic of Sudan, 34: 1-20.

Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith