OPENING OF THE CENTRAL ATLANTIC AND ASYMMETRIC MANTLE UPWELLING PHENOMENA - IMPLICATIONS FOR LONG-LIVED MAGMATISM IN WESTERN NORTH-AFRICA AND EUROPE

The Mesozoic to present evolution of the central Atlantic realm is int erpreted as a two-stage tectonomagmatic scenario involving long-lived asymmetric mantle upwelling phenomena and magmatism within its eastern margin. The first, a pre-drift tholeiitic stage of Triassic-Jurassic age, resulted from the interaction between several elements: (1) a thi nned, weakened corridor along the collapsed southern branch of the Var iscan belt between eastern North America and western North Africa; (2) a central Atlantic plume located in the triple junction between Afric a, North America, and South America; (3) a progressive asymmetric cont inental breakup between northwest Africa and North America characteriz ed by detachment systems; and (4) a highly thinned European realm perv aded by rift-type basins that we interpret as a large thin-spot-type d omain. These conditions would have induced north-northeast-directed la rge-scale sublithospheric plume channeling from the central Atlantic p lume site to the European large thin-spot, leading to widespread early tholeiitic magmatism (Triassic-Jurassic) within a giant irregular zon e of similar to 3000 x 4000 km. plume activity and channeling continue d afterward during a Cretaceous to present second tectonomagmatic stag e (passive margin alkaline stage) leading to the onset of alkaline mag matism along a general north-northeast trend in the eastern Atlantic m argin (Late Cretaceous) and Europe (Paleocene-Oligocene). As a whole, a north-northeast-directed propagating magmatic vector can be defined from the Mesozoic to the present.