Faeroe-Iceland plume: Rare-earth evidence

Schilling, Jean-Guy; Noe-Nygaard, Arne

doi:10.1016/0012-821x(74)90002-8

Cited by 135 publications

(71 citation statements)

References 39 publications

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“…Modern Icelandic volcanism taps a geochemically heterogeneous mantle that includes both "depleted" and relatively "enriched" portions as defined by incompatible element ratios such as (La/Sm) N (e.g., Hemond et al, 1993;Schilling and Noe-Nygaard, 1974;Schilling et al, 1983). Given the similarity in incompatible element ratios between the Site 918 unit and modern Icelandic lavas , and the progressive shift in incompatible element ratios from the Site 917 upper series group 2 to the Site 915 to the Site 918 lavas, we suggest that both the Sites 915 and 918 and the Site 917 upper series group 2 lavas were derived from a mantle source with composition like the depleted end of the mantle currently tapped by Icelandic volcanism (see also Fitton et al,Chap.…”

Section: Transition Pressurementioning

confidence: 99%

“…The hot spot is currently a pronounced thermal and chemical anomaly on the Mid-Atlantic Ridge in the immediate vicinity of Iceland, and its influence can be traced south for more than 400 km along the Reykjanes Ridge (e.g., Schilling and Noe-Nygaard, 1974;Schilling et al, 1983;Klein and Langmuir, 1987). Recent workers (White and McKenzie, 1989;Campbell and Griffiths, 1990) have argued that, in the early Tertiary, the hot spot was a much larger feature, underlying the whole North Atlantic region that experienced volcanism, from West Greenland to the British Isles and along 2000 km of the East Greenland and conjugate European margins.…”

Section: Introductionmentioning

confidence: 99%

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Mantle melting systematics: transition from continental to oceanic volcanism on the southeast Greenland Margin

Fram¹,

Lesher²,

Volpe³

1998

Proceedings of the Ocean Drilling Program

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We present trace element analyses of basaltic and picritic lavas recovered from the Ocean Drilling Program Leg 152 transect on the southeast Greenland volcanic rifted margin. These lavas span the stratigraphic interval from continental to oceanic magmatism. Incompatible element patterns define two geochemical groups within the Site 917 upper series. Group 1 flows are characterized by (La/Sm) N = 0.3−0.8, whereas group 2 flows have (La/Sm) N = 0.7−1.2 and higher mantle-normalized Th, Ba, and Pb, and lower Nb and U concentrations. The transition upsection from group 1 to group 2 at Site 917 occurs between 114 and 65 meters below seafloor, and is represented by interfingering of flows belonging to the two groups. (La/Sm) N , Ba/Zr, and Th/Pb ratios and mantle-normalized incompatible element concentrations decrease systematically with stratigraphic height within each group, and the Site 915 and Site 918 units are generally continuous with group 2. These variations imply an increase in the extent of partial melting with time. Lu/Hf ratios vary from 0.14 to 0.25 through the upper series and into the Site 915 and Site 918 flows. This relationship suggests the importance of residual garnet in the mantle source melting decreased with time. We develop a quantitative model for mantle melting to investigate melting systematics responsible for these relationships. Comparison between observed data and model results suggests a progressive increase in the extent of partial melting (from 4% to 12%) and decrease in mean pressure of melting with time. This temporal evolution of primary magma compositions is explicable by rapid thinning of the continental lithosphere during eruption of the upper series. We conclude that group 1 units were derived from mantle with normal mid-ocean-ridge basalt source characteristics, whereas units from group 2 and from Sites 915 and 918 were derived from a source similar to depleted Icelandic mantle. We infer that the thermal anomaly associated with the ancestral Iceland plume pre-dated the transition in mantle source compositions.

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Section: Transition Pressurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mantle melting systematics: transition from continental to oceanic volcanism on the southeast Greenland Margin

Fram¹,

Lesher²,

Volpe³

1998

Proceedings of the Ocean Drilling Program

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“…1). As a whole the geochemistry of Leg 81 basalts contrasts with that of most of these basaltic sequences, in which LREE-enriched alkalic or transitional magmas do predominate (Schilling and Noe-Nygaard, 1974;Thompson, 1982). However some similarities do appear, and further detailed comparisons are needed to place Leg 81 basalts in the magmatic context of the Thulean Province.…”

Section: Comparison With Other Thulean Basaltsmentioning

confidence: 99%

“…Schilling and Noe-Nygaard (1974) have described an abrupt change from LREE-enriched to LREE-depleted patterns near the boundary of the Middle and Upper Series of the Faeroes Plateau Basalt. Although they have not found extremely low La contents such as those of Table 6, some of their data (La content close to 2 ppm: see Schilling and Noe-Nygaard's table 1) overlap with Leg 81 ones; they have attributed this change to a transition in magmatic regime from plume-derived to oceanic type.…”

Section: Comparison With Other Thulean Basaltsmentioning

confidence: 99%

Strongly Depleted Tholeiites from the Rockall Plateau Margin, North Atlantic: Geochemistry and Mineralogy

Joron¹,

Bougault²,

Maury³

et al. 1984

Initial Reports of the Deep Sea Drilling Project

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The Leg 81 basalts, drilled either from the margins ("dipping reflectors" sequence: Holes 552, 553A, and 554A) or from the "continental" side (Hole 555) of the Rockall Plateau microcontinent, are strongly light rare-earth element (LREE) depleted oceanic tholeiites. The basalts from the four holes are almost similar. Most of their primary characteristics have been preserved, although they have suffered alteration by seawater. From the petrological and mineralogical points of view, they resemble deep-ocean-floor basalts but show some peculiarities (occurrence of pigeonite and ilmenite as normal components of the groundmass differentiation sequences toward ferrobasalts). Their geochemical characteristics are dominated by their extreme depletion in the most hygromagmaphile elements (Th, Ta, La, and Nb), the concentrations of which are sometimes lower than the corresponding chondritic values. Leg 81 basalts are thus clearly different from continental tholeiites (flood basalts): Possible equivalents in the Thulean Tertiary Magmatic Province include the LREE-depleted tholeiites from the Upper Basaltic Series of the Faeroe Islands and the Preshal Mhor basalt type from the British Tertiary Province.

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“…Temporal chemical variations in Iceland plume magmas were related by Schilling and Noe-Nygaard (1974) and Schilling et al (1983) to changes in plume flux rather than to plume composition. Humphris andThompson (1982, 1983) concluded that chemical variations in Walvis Ridge basalts mainly reflected a change in the location of the Tristan plume from on-ridge to off-ridge rather than to a change in the composition of the plume.…”

mentioning

confidence: 94%

Isotope Geochemistry of Leg 115 Basalts and Inferences on the History of the Réunion Mantle Plume

White¹,

Cheatham²,

Duncan³

1990

Proceedings of the Ocean Drilling Program

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Strontium, neodymium, and lead isotope ratios are reported for 13 Leg 115 basalts as well as 3 basalts from Texaco drill hole SM-1 on the Mascarene Plateau. Pb ratios, typical of Indian Ocean mid-ocean ridge (MORB) and oceanic-island basalts (OIB). Isotopic compositions of Leg 115 basalts generally fall between fields for MORB and Reunion Island basalts, consistent with the conclusion drawn from geochronological studies that Deccan flood basalt volcanism, the Chagos-Laccadive Ridge, and the Mascarene Plateau are all products of the Reunion mantle plume. Isotopic compositions of magmas produced by this plume have varied systematically with time in the direction of less "depleted," less MORB-like isotopic signatures. This compositional change has been accompanied by a decrease in eruption rate. We interpret Deccan volcanism as the voluminous beginning of the plume. Reduced entrainment of asthenosphere following melting of the plume head resulted in less MORB-like isotope ratios in magmas and a decrease in eruptive activity with time.

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Faeroe-Iceland plume: Rare-earth evidence

Cited by 135 publications

References 39 publications

Mantle melting systematics: transition from continental to oceanic volcanism on the southeast Greenland Margin

Mantle melting systematics: transition from continental to oceanic volcanism on the southeast Greenland Margin

Strongly Depleted Tholeiites from the Rockall Plateau Margin, North Atlantic: Geochemistry and Mineralogy

Isotope Geochemistry of Leg 115 Basalts and Inferences on the History of the Réunion Mantle Plume

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