Palaeozoic and Mesozoic age trends for some ring complexes in Niger and Nigeria

Magmatism and rifting in Western and Central Africa, from Late Jurassic to Recent times

“…Their origin is controversial. Earlier hypotheses suggested that the magmatism was triggered by the northward migration of the African plate over a mantle plume (Bowden and Turner, 1974;Bowden et al, 1976;Karche and Vachette, 1976). However, more recently it has been suggested that they are linked to shear movements along pre-existing ENE-WSW trending wrench faults in the Pan African basement (Rahaman et al, 1984;Black et al, 1985).…”

The North–South Paleozoic to Quaternary trend of alkaline magmatism from Niger–Nigeria to Cameroon: Complex interaction between hotspots and Precambrian faults

“…On the basis of ages decreasing from the Aïr ring complexes, North of Niger (480-400 Ma) to the Younger Granites of Nigeria in the South (215-140 Ma) through the Damagaram, South of Niger (330-260 Ma) (Bowden et al, 1976;Karche and Vachette, 1978), the Niger-Nigeria large magmatic province has been defined as a unique feature in the world of practically continuous within plate anorogenic volcanism and plutonism with progressive southern shift of centers of magmatic activity (Bowden and Karche, 1984). At the scale of the Aïr province alone, the ages would decrease from 487 Ma in the North to 407 Ma in the South (Bowden and Karche, 1984).…”

Ba/Rb and Rb/Sr ratios as indicators of magmatic fractionation, postmagmatic alteration and mineralization - Afu younger granite complex, northern Nigeria.

“…The Afu Younger Granite Complex occupies an area of approximately 373 km' and was em placed 144 ± 2 million years ago (BOWDEN et al, 1976). It is the southernmost part of the Ni gerian Younger Granite group of complexes ( Fig.…”

“…(BOWDEN et al, 1976) is elliptical in outline (Fig. 2), about 48 km in maximum diameter and comprises an outer ring dike of quartz porphyry and a core of composite granitic intrusives.…”