Geochemistry of North Atlantic Igneous Province basalts

• Main Authors: Kempton, Pamela D, Fitton, J Godfrey, Saunders, Andrew D, Nowell, G M, Taylor, R N, Hardarson, B S, Pearson, Grant
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2000
• Subjects: 152-917A; 152-918D; 163-988A; 163-989B; 163-990A; 38-348; 49-407; 49-408; 49-409; 49-411; 49-413; 80-550; 80-551; 81-553A; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Greenland Sea; Joides Resolution; Leg152; Leg163; Leg38; Leg49; Leg80; Leg81; North Atlantic/BASIN; North Atlantic/ESCARPMENT; North Atlantic/FRACTURE ZONE; North Atlantic/Norwegian Sea/PLATEAU; North Atlantic/PLAIN; North Atlantic/PLATEAU; North Atlantic/RIDGE; Ocean Drilling Program; ODP; Greenland; Iceland; Kolbeinsey; North Atlantic; Norwegian Sea; Ocean Island
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.716921; https://doi.org/10.1594/PANGAEA.716921

New Sr-Nd-Pb-Hf data require the existence of at least four mantle components in the genesis of basalts from the the North Atlantic Igneous Province (NAIP): (1) one (or more likely a small range of) enriched component(s) within the Iceland plume, (2) a depleted component within the Iceland plume (distinct from the shallow N-MORB source), (3) a depleted sheath surrounding the plume and (4) shallow N-MORB source mantle. These components have been available since the major phase of igneous activity associated with plume head impact during Paleogene times. In Hf-Nd isotope space, samples from Iceland, DSDP Leg 49 (Sites 407, 408 and 409), ODP Legs 152 and 163 (southeast Greenland margin), the Reykjanes Ridge, Kolbeinsey Ridge and DSDP Leg 38 (Site 348) define fields that are oblique to the main ocean island basalt array and extend toward a component with higher 176Hf/177Hf than the N-MORB source available prior to arrival of the plume, as indicated by the compositions of Cretaceous basalts from Goban Spur (~95 Ma). Aside from Goban Spur, only basalts from Hatton Bank on the oceanward side of the Rockall Plateau (DSDP Leg 81) lie consistently within the field of N-MORB, which indicates that the compositional influence of the plume did not reach this far south and east ~55 Ma ago. Thus, Hf-Nd isotope systematics are consistent with previous studies which indicate that shallow MORB-source mantle does not represent the depleted component within the Iceland plume (Thirlwall, J. Geol. Soc. London 152 (1995) 991-996; Hards et al., J. Geol. Soc. London 152 (1995) 1003-1009; Fitton et al., 1997 doi:10.1016/S0012-821X(97)00170-2). They also indicate that the depleted component is a long-lived and intrinsic feature of the Iceland plume, generated during an ancient melting event in which a mineral (such as garnet) with a high Lu/Hf was a residual phase. Collectively, these data suggest a model for the Iceland plume in which a heterogeneous core, derived from the lower mantle, consists of 'enriched' streaks or blobs dispersed in ...