By far the most voluminous volcanic province in Libya, Al Haruj covers over 45,000 km2. The province is essentially basaltic with all rocks analysed so far (Almond, 1974; Busrewil and Wadsworth, 1980b) being nepheline normative. The average of 12 analyses given by Almond (1974) contains 12.4% normative nepheline, indicating that basanites are well represented and that modal nepheline is likely to be present. A detailed palaeomagnetic study was made by Ade-Hall (1974).
ADE-HALL, J.M., REYNOLDS, P.H., DAGLEY, P., MUSSETT, A.E., HUBBARD, T.P. and KLITZSCH, E. 1974. Geophysical studies of North African Cenozoic volcanic areas: I. Haruj Assuad, Libya. Canadian Journal of Earth Sciences, 11: 998-1006.ALMOND, D.C. 1974. The composition of basaltic lavas from Bayuda, Sudan and their place in the Cainozoic volcanic history of north-east Africa. Bulletin Volcanologique, 38: 345-60.BUSREWIL, M.T. and WADSWORTH, W.J. 1980b. Preliminary chemical data on the volcanic rocks of Al Haruj area, central Libya. In M.J. Salem and M.T. Busrewil (eds) The geology of Libya, 3: 1077-80. Academic Press, London.