Renewed melting at the abandoned Húnafloí Rift, northern Iceland, caused by plume pulsing

• Published in: Earth and planetary science letters 2013-09, Vol.377-378, p.227-238
• Main Authors: Walters, R.L., Jones, S.M., Maclennan, J.
• Format: Article
• Language: English
• Subjects: Húnafloí Rift at Skagi; Iceland; plume pulsing; plume–ridge interaction; rift relocation
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2013.06.040

The abandoned Húnafloí Rift (HR), near Skagi in northern Iceland, provides an opportunity to investigate how relocation of an oceanic spreading ridge influences melt generation. Melting recommenced beneath HR several million years after spreading ceased at 7–4 Ma. Both the older (pre-HR abandonment) and younger (post-abandonment) lavas are tholeiitic basalts with high Fe–Ti and enriched incompatible trace element compositions. The HR lavas are compositionally similar to modern lavas from central Iceland (above the Iceland Plume conduit) and the Eastern Volcanic Zone (a propagating rift). Although older and younger HR lavas are compositionally similar, geological and geophysical observations indicate different mantle melting conditions. For the older lavas, a plume migration reconstruction suggests that the combination of incompatible trace element enrichment and crustal thickness of ∼25 km can be explained by plume-driven upwelling, a scenario similar to central Iceland at present. The smaller volume of the younger HR lavas (