Geochemical and isotopic (Sr, Nd, and Pb) features of representative alkaline basalts from the eastern Atlantic (Serra de Monchique-Mt. Ormonde, Madeira, Canary and Cape Verde Islands), northern Africa (Morocco, Algeria, Tunisia), central Europe (French Massif Central, Rhon-Eifel, Austria, Poland, Czech Republic, Hungary, Italy), and also from the Tertiary British Province and Iceland, are characterized by a common mantle component with a typical OIB-HIMU signature. This mantle source appears to have its purest fingerprint in the eastern Atlantic (Cape Verde, Madeira, and Canary Islands), while it becomes more diluted both eastwards and northwards. In an eastwards direction, the dilution is caused by a crustal component (progressively increasing from Morocco-Algeria to Tunisia, and from the French Massif to Poland). In a northward direction, a DM component becomes important (Tertiary British Province and Iceland), likely related to the Mid-Atlantic Ridge. Tomographic images from whole mantle models below the eastern Atlantic, northern Africa and central Europe show a widespread low sesmic velocity zone below 900 km depth (Goes et al., 1999). While the transition zone under central-western Europe and Mediterranean is characterized by a wide, recumbent high velocity feature (Goes et al., 1999), the top most mantle, above 400 km depth, appears again dominated by a low-velocity zone on a large scale (Hoernle et al., 1995; Piromallo and Morelli, in press). The geophysical and geochemical data can be accounted for in terms of a hypothesis postulating a common and primary deep mantle plume material, upwelling beneath the Cape Verde-Madeira-Canary Islands region. It is possible to suggest that the head of this large-scale swell has been frayed by Eurasia, that moved at this latitude towards the northeast, and trapped in the shallower mantle (above the transition zone) by subduction episodes. At different times local extensional tectonics and slab rupture may favor plume related volcanism, also in areas dominated by plate convergence and subduction (Gasperini et al., 2002).
Where is the tail of the European plume volcanism?
MACERA, PATRIZIA;
2003-01-01
Abstract
Geochemical and isotopic (Sr, Nd, and Pb) features of representative alkaline basalts from the eastern Atlantic (Serra de Monchique-Mt. Ormonde, Madeira, Canary and Cape Verde Islands), northern Africa (Morocco, Algeria, Tunisia), central Europe (French Massif Central, Rhon-Eifel, Austria, Poland, Czech Republic, Hungary, Italy), and also from the Tertiary British Province and Iceland, are characterized by a common mantle component with a typical OIB-HIMU signature. This mantle source appears to have its purest fingerprint in the eastern Atlantic (Cape Verde, Madeira, and Canary Islands), while it becomes more diluted both eastwards and northwards. In an eastwards direction, the dilution is caused by a crustal component (progressively increasing from Morocco-Algeria to Tunisia, and from the French Massif to Poland). In a northward direction, a DM component becomes important (Tertiary British Province and Iceland), likely related to the Mid-Atlantic Ridge. Tomographic images from whole mantle models below the eastern Atlantic, northern Africa and central Europe show a widespread low sesmic velocity zone below 900 km depth (Goes et al., 1999). While the transition zone under central-western Europe and Mediterranean is characterized by a wide, recumbent high velocity feature (Goes et al., 1999), the top most mantle, above 400 km depth, appears again dominated by a low-velocity zone on a large scale (Hoernle et al., 1995; Piromallo and Morelli, in press). The geophysical and geochemical data can be accounted for in terms of a hypothesis postulating a common and primary deep mantle plume material, upwelling beneath the Cape Verde-Madeira-Canary Islands region. It is possible to suggest that the head of this large-scale swell has been frayed by Eurasia, that moved at this latitude towards the northeast, and trapped in the shallower mantle (above the transition zone) by subduction episodes. At different times local extensional tectonics and slab rupture may favor plume related volcanism, also in areas dominated by plate convergence and subduction (Gasperini et al., 2002).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
