EVIDENCE FOR 2 DISTINCT THOLEIITIC SERIES IN UPPER PROTEROZOIC DOLERITES OF IRHERM INLIER (ANTI-ATLAS, MOROCCO)

During Upper Proterozoic times, the Irherm inlier was intersected by N E-SW doleritic dikes. These dolerites are strongly altered. The primar y association included plagioclase, micropegmatite, pyroxene, hornblen de (ferro-edenite), ilmenite and aparite. Taking only into account the contents of elements which appear generally as inert in alteration ph enomena, these dolerites have a composition af continental tholeiites. Two groups may be distinguished according to Ti, Fe, Co, V, Ni conten ts, which are higher in the first one (group A) than in the other one (group B). This tholeiitic magnetism in the Irherm inlier is in agreem ent with distension which occurred in the whole Anti-Atlas at Upper Pr oterozoic.