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North Atlantic hotspot-ridge interaction near Jan Mayen Island

L.J. Elkins1,2,

1Department of Geology, Bryn Mawr College, 101 North Merion Avenue, Bryn Mawr, Pennsylvania 19010, USA
2Department of Earth and Atmospheric Sciences, University of Nebraska Lincoln, Lincoln, NE 68588, USA

C. Hamelin3,

3Center for Geobiology, University of Bergen, Allegaten 41 5007, Bergen, Norway

J. Blichert-Toft4,

4Laboratoire de Géologie de Lyon, Ecole Normale Superieure de Lyon, 46 Allée d’Italie, 69007 Lyon, France

S.R. Scott5,

5Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071, USA

K.W.W. Sims5,

5Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071, USA

I.A. Yeo6,

6GEOMAR, Helmholtz Center for Ocean Research Kiel, Wischhofstraße 1-3 24148, Kiel, Germany

C.W. Devey6,

6GEOMAR, Helmholtz Center for Ocean Research Kiel, Wischhofstraße 1-3 24148, Kiel, Germany

R.B. Pedersen3

3Center for Geobiology, University of Bergen, Allegaten 41 5007, Bergen, Norway

Affiliations  |  Corresponding Author  |  Cite as

Elkins, L.J., Hamelin, C., Blichert-Toft, J., Scott, S.R., Sims, K.W.W., Yeo, I.A., Devey, C.W., Pedersen, R.B. (2016) North Atlantic hotspot-ridge interaction near Jan Mayen Island. Geochem. Persp. Let. 2, 55-67.

Geochemical Perspectives Letters v2, n1  |  doi: 10.7185/geochemlet.1606
Received 17 August 2015  |  Accepted 21 December 2015  |  Published 22 January 2016
Copyright © 2016 European Association of Geochemistry

Figure 1 (a) Multibeam bathymetric map of the NKR, showing the Eggvin Bank and numbered dredge locations for samples analysed in this study. (b) Regional bathymetric map showing distribution of labelled seafloor features and Jan Mayen Island, with sample locations for this study from Jan Mayen Island (red), NKR (colours as in panel a), and SMR (orange). (c) Map with highlighted areas showing the proposed zones of underlying mantle melt generation and migration (blue: Kolbeinsey-type; purple: Eggvin-type; orange: Mohns-type; and red circle: Jan Mayen-type mantle).
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Table 1 Radiogenic isotope compositions measured by ICP-MS.*
Submarine samples:
POS436 242DR-2baNKR0.703151(5)0.283175(5)0.513006(6)18.892615.509338.6157
POS436 246DR-2aNKR0.702961(6)0.283255(4)0.513083(5)18.455315.454738.0857
POS436 235DR-1aaNKR0.703187(5)0.283177(4)0.513008(5)18.875615.517738.5990
POS436 253DR-E2aNKR0.703195(7)0.283175(4)0.513015(5)18.889915.521138.6184
POS436 253DR-6aNKR0.703203(7)0.283183(4)0.513019(5)18.888115.518538.6109
POS436 232DR-1aNKR0.703047(7)0.283217(4)0.513044(5)18.788115.500438.4908
POS436 209DR-2aaNKR0.703034(6)0.283231(4)0.513051(6)18.769915.500338.4689
POS436 222DR-1aNKR0.703040(7)0.283217(4)0.513043(6)18.815015.504738.5277
POS436 215DR-1aNKR0.703047(7)0.283203(4)0.513036(4)18.853815.511438.5652
Subaerial samples (samples from Maaløe et al., 1986

Maaløe, S., Sørensen, I. B., Hertogen, J. (1986) The trachybasaltic suite of Jan Mayen. Journal of Petrology 27, 439-466.


* Values in parentheses indicate 2s uncertainty for the last digit expressed.
** NKR: Northern Kolbeinsey Ridge; JM: Jan Mayen Island; SMR: Southern Mohns Ridge.
a 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 176Hf/177Hf, and 143Nd/144Nd measured by MC-ICP-MS (Nu Plasma HR) at the Ecole Normale Supérieure de Lyon. Strontium isotopes were analyzed at the University of Wyoming by MC-ICP-MS (ThermoFinnigan NeptunePlus). See Supplementary

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Figure 2 (a) εNd vs. εHf, (b) εNd vs. 206Pb/204Pb, (c) 207Pb/204Pb vs. εHf, and (d) 207Pb/204Pb vs. 206Pb/204Pb diagrams for lavas from the Jan Mayen region and Iceland (Sun and Jahn, 1975; Zindler et al., 1979; Óskarsson et al., 1982; Hemond et al., 1993; Nowell et al., 1998; Salters and White, 1998; Schilling et al., 1999; Chauvel and Hémond, 2000; Kempton et al., 2000; Stracke et al., 2003; Blichert-Toft et al., 2005; Elkins et al., 2011; Sims et al., 2013; Elkins et al., 2014) (Tables 1, S-2). Curves show calculated binary mixing trajectories between hypothesised geochemical compositions for Jan Mayen- (red box), Mohns- (yellow), Kolbeinsey- (blue) and Eggvin- (green) type melt endmembers, where tickmarks show percentage contributions of a pure Jan Mayen- or Eggvin-derived magma to a mixture. The Jan Mayen endmember, based on the most extreme enriched measurements for the island (Tables 1, S-2) has εHf = +10.5, εNd = +4.7, 206Pb/204Pb = 18.85, 207Pb/204Pb = 15.517, and Hf, Nd, and Pb concentrations of 6.9, 38.7, and 3.7 ppm, respectively. The hypothesised Mohns endmember, extrapolated to values that best explain available SMR samples as binary mixtures of Jan Mayen-Mohns Ridge lavas, has εHf = +24, εNd = +10.1, 206Pb/204Pb = 17.9, 207Pb/204Pb = 15.41, and Hf, Nd, and Pb concentrations of 5.6, 30, and 0.7, ppm, respectively; this composition is reasonable compared to published measurements from the Mohns Ridge (Schilling et al., 1983; Schilling et al., 1999; Blichert-Toft et al., 2005; Elkins et al., 2014). The Kolbeinsey endmember, based on depleted values from a suite of published MKR measurements (Schilling et al., 1983; Blichert-Toft et al., 2005; Elkins et al., 2011) and NKR sample POS436 246DR-2, has εHf = +19.2, εNd = +10, 206Pb/204Pb = 18.0, 207Pb/204Pb = 15.43, and Hf, Nd, and Pb concentrations of 0.5, 3, and 0.3 ppm, respectively; mixtures of Jan Mayen and Kolbeinsey endmembers cannot fully explain NKR lava compositions. The Eggvin-type component was extrapolated to values that best explain NKR basalts as mixtures between Kolbeinsey and an unknown enriched component, with εHf = +11, εNd = +5, 206Pb/204Pb = 18.96, 207Pb/204Pb = 15.528, 208Pb/204Pb = 38.72, and Hf, Nd, and Pb concentrations of 3, 22, and 11 ppm. Note that the high Pb content of the Eggvin-type endmember is necessary to generate a sufficiently hyperbolic mixing trajectory to account for NKR basalts.
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Figure 3 Geochemical indicators vs. along-axis distance for the NKR and SMR, with the position of Jan Mayen Island projected westward onto the NKR using a geographic contour that runs parallel to the Jan Mayen Fracture Zone. (a) (Sm/Yb), sensitive to the presence of garnet in, and the trace element makeup of, the source. The variation between Jan Mayen Island/SMR and the NKR likely reflects a heterogeneous mantle source. (b) αSm-Nd; because Sm is always more compatible than Nd during melting, values less than unity reflect the degree of melting of the model source, while values greater than unity (e.g., MKR basalts; Salters, 1996; Elkins et al., 2011) require a different source composition and/or younger age than recorded by radiogenic isotopes.
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Supplementary Figures and Tables

Figure S-1 (a) Chondrite-normalised (McDonough and Sun, 1995) REE concentrations and (b) N-MORB (Hofmann, 1988) normalised trace element concentrations for samples from this study (Table S-2). NKR basalts have elevated Pb and HREE compared to Jan Mayen Island and the MKR, indicating that they cannot be simple mixtures of Kolbeinsey-type and Jan Mayen-type magmas. High (230Th/238U) ratios measured in NKR lavas also require the presence of garnet in the melt source, indicating that the trace element compositions in Eggvin Bank basalts is principally controlled by mantle source composition.
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Figure S-2 εHf vs. 206Pb/204Pb for the Jan Mayen region, with symbols, mixing trajectories, and references as in Figure 2.
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Figure S-3 (La/Sm) vs. FeO* for basalt samples from the Kolbeinsey Ridge and the NKR, using data from Haase et al. (2003)

Haase, K.M., Devey, C.W., Wieneke, M. (2003) Magmatic processes and mantle heterogeneity beneath the slow-spreading northern Kolbeinsey Ridge segment, North Atlantic. Contributions to Mineralogy and Petrology 144, 428-448.

and C. Devey, M. Wieneke, and K. Haase (unpub. data). Linear best-fit regression for Kolbeinsey Ridge samples suggests a slight positive relationship between FeO* and (La/Sm)N, likely controlled by degree of melting. Basalt rocks from the NKR are restricted to generally higher (La/Sm)N and lower FeO* values than the rest of the Kolbeinsey Ridge, best explained by an eclogite-bearing, incompatible element-enriched mantle source beneath the Eggvin Bank.
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Figure S-4 (a) 87Sr/86Sr vs. Pb, and (b) εNd vs. Pb. for the Jan Mayen region, with symbols and references as in Figure 2. The data support lithologically and isotopically heterogeneous mantle source compositions for the Jan Mayen region and corroborate the existence of an Eggvin Bank end-member distinct from Jan Mayen mantle.
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Table S-1 Location information for new submarine samples analyzed in this study.
Sample number*LocationExpeditionbYearLatitude (ºN)Longitude (ºW)Depth (m)
POS436 242DR-2bNKRR/V Poseidon Leg 436201270.7599770.7649813.5503513.5448315591436
POS436 246DR-2NKRR/V Poseidon Leg 436201270.7894270.7947213.7535013.7540017141630
POS436 235DR-1aNKRR/V Poseidon Leg 436201270.9127570.9123713.1240813.11248485381
POS436 253DR-E2NKRR/V Poseidon Leg 436201270.9489770.9474213.0347513.03770207175
POS436 253DR-6NKRR/V Poseidon Leg 436201270.9489770.9474213.0347513.03770207175
POS436 232DR-1NKRR/V Poseidon Leg 436201271.0598771.0565512.9523212.93983622578
POS436 209DR-2aNKRR/V Poseidon Leg 436201271.3134271.3159212.7027212.6944711991205
POS436 222DR-1NKRR/V Poseidon Leg 436201271.3470071.3472012.6433312.6292511391137
POS436 215DR-1NKRR/V Poseidon Leg 436201271.4766071.4759712.3938312.4061718191703
SM01-DR-24-14aJMR/V Håkon Mosby. SM012001-71.1287-7.8082-738
SM01-DR-23-3JMR/V Håkon Mosby. SM012001-71.1022-7.7913-697
SM01-DR-5-5JMR/V Håkon Mosby. SM012001-71.1192-7.9187-47
SM01-DR-60-43JMR/V Håkon Mosby. SM012001-71.1645-7.9880-222
SM01-DR-100-01SMRR/V Håkon Mosby. SM012001
CGB-2011-D17-2aSMRR/V G.O. Sars. CGB2011201171.2616771.26135.843005.8397-847
SM01-DR70-1SMRR/V Håkon Mosby. SM012001-71.2382-6.1102-953
SM01-DR67-4SMRR/V Håkon Mosby. SM012001-71.2188-6.1713-806
SM01-DR-91-13SMRR/V Håkon Mosby. SM012001-71.2715-5.8468-732

* All samples collected by dredge, except ROV dive sample CGB-2011-D17-2a. For SM01 cruise, only end locations for dredges were recorded.
a SM01 and CGB-2011 sample depths are calculated from GEBCO global bathymetry (IOC, IHO, BODC, 2003 IOC, IHO, BODC (2003) Centenary Edition of the GEBCO Digital Atlas, published on CD-ROM on behalf of the Intergovernmental Oceanographic Commission and the International Hydrographic Organization as part of the General Bathymetric Chart of the Oceans, Liverpool, UK. ).
b R/V Poseidon sample information available in Earthchem/IEDA database (Elkins, 2015).

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Table S-2 Trace element abundance measured by ICP-MS.
Submarine samples:
POS436 242DR-2baNKR4.947.8274.7404.145.6127.
POS436 246DR-2aNKR4.546.9275.3246.049.485.7110.272.41.656.436.523.90.2-2.3
POS436 235DR-1aaNKR7.743.7424.418.143.820.149.9104.212.0150.0118.639.60.9172.215.4
POS436 253DR-E2aNKR6.836.9409.014.642.9174.649.1105.811.6140.4128.234.61.0175.715.1
POS436 253DR-6aNKR6.630.2402.319.443.238.873.8160.411.4138.1132.432.61.2173.213.7
POS436 232DR-1aNKR4.947.9280.4376.346.2106.392.373.
POS436 209DR-2aaNKR6.752.9329.2173.947.655.777.489.96.4103.252.433.20.466.45.8
POS436 222DR-1aNKR5.547.4302.1226.047.074.388.483.24.8110.350.627.70.572.36.0
POS436 222DR-1 replicateaNKR5.449.2311.1233.248.574.491.687.35.2114.652.728.60.575.16.2
POS436 215DR-1aNKR5.838.3332.287.647.451.676.098.76.6100.161.825.60.6103.47.2
Subaerial samples (samples from Maaløe et al., 1986 Maaløe, S., Sørensen, I.B., Hertogen, J. (1986) The trachybasaltic suite of Jan Mayen. Journal of Petrology 27, 439-466. ):
Rock standard:
Submarine samples:
POS436 242DR-2ba16.
POS436 246DR-2a6.
POS436 235DR-1aa33.
POS436 253DR-E2a34.
POS436 253DR-6a32.43.715.
POS436 232DR-1a11.
POS436 209DR-2aa12.
POS436 222DR-1a12.
POS436 222DR-1 replicatea12.
POS436 215DR-1a15.
Subaerial samples (samples from Maaløe et al., 1986 Maaløe, S., Sørensen, I.B., Hertogen, J. (1986) The trachybasaltic suite of Jan Mayen. Journal of Petrology 27, 439-466. ):
Rock standard:

a Trace elements measured by ICP-MS (VG Plasma Quad ExCell) at Boston University, with 1-2 % standard deviations.
b Trace elements measured by LA-ICP-MS (Thermo-Finnigan Element2) at the University of Bergen, with 2-5 % standard deviations.

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Table S-3 Major element composition results.
SampleLocationSiO2 Al2O3 TiO2 CaO MnOMgO FeOFe2O3 Na2O K2O Cr2O3 P2O5 Cl Total
Submarine samples:
POS436 242DR-2bNKR50.69(8)15.25(4)1.04(2)13.02(4)-8.37(5)8.66(5)-1.70(1)0.267(4)0.09(1)0.144(7)0.032(2)99.4(1)
POS436 246DR-2NKR50.73(9)15.02(4)0.85(3)13.64(6)-8.95(3)9.16(7)-1.57(1)0.074(3)0.07(1)0.094(7)0.012(1)100.3(1)
POS436 235DR-1aNKR52.27(9)13.06(4)2.25(5)8.68(5)-4.54(3)14.60(6)-2.76(2)0.551(4)0.031(9)0.22(1)0.141(3)99.3(2)
POS436 253DR-E2NKR52.5(2)11.9(9)2.0(1)9.8(6)-6.2(1.3)13.6(2)-2.5(3)0.45(5)0.03(1)0.20(2)0.14(2)99.5(2)
POS436 253DR-6NKR52.70(8)12.8(5)2.06(7)9.1(2)-5.4(7)13.66(7)-2.7(1)0.50(3)0.034(9)0.22(1)0.149(8)99.5(2)
POS436 232DR-1NKR50.90(7)14.83(3)1.00(3)13.16(5)-8.30(3)9.30(6)-1.777(9)0.192(2)0.07(1)0.074(5)0.028(1)99.8(1)
POS436 209DR-2aNKR52.2(1)13.03(4)2.28(3)8.68(3)-4.57(2)14.70(7)-2.75(2)0.568(2)0.05(1)0.233(8)0.143(2)99.4(2)
POS436 222DR-1NKR51.4(1)14.58(4)1.10(2)12.44(5)-7.56(7)10.22(5)-1.95(3)0.230(3)0.06(1)0.095(7)0.026(1)99.9(1)
POS436 215DR-1NKR52.24(7)14.24(4)1.25(3)11.09(6)-6.64(3)11.50(7)-2.088(8)0.309(3)0.027(7)0.121(8)0.038(2)99.7(1)
Subaerial samples (samples from Maaløe et al., 1986 Maaløe, S., Sørensen, I.B., Hertogen, J. (1986) The trachybasaltic suite of Jan Mayen. Journal of Petrology 27, 439-466. ):
Rock standard:

* Major element concentrations of glass chips measured by EPMA methods unless otherwise indicated. EPMA results report uncertainties expressed in parentheses as 1s standard error for the last digit reported. Values shown are mean values of at least 15 analysed points, measured using a 20 keV beam. All Fe measured as FeO.
a Whole rock chips analysed for major element concentrations by ICP-ES (Jobin-Yovn Ultima-C) with standard deviations of 1-2 %. All Fe measured as Fe2O3.

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