Skip to main content

Petrology of basalts from the Mohns-Knipovich Ridge; the Norwegian-Greenland Sea

Abstract

Major element compositions of submarine basalts, quenched glasses, and contained phenocrysts are reported for samples from 25 dredge stations along the Mohns-Knipovich Ridge between the Jan Mayen fracture zone and 77°30′N. Most of the basalts collected on the Jan Mayen platform have a subaerial appearance, are nepheline normative, rich in incompatible elements, and have REE-patterns strongly enriched in light-REE. The other basalts (with one exception) are tholeiitic pillow basalts, many of which have fresh quenched glass rims. From the Jan Mayen platform northeastwards the phenocryst assemblage changes from olivine±plagioclase±clinopyroxene±magnetite to olivine +plagioclase±chrome-spinel. This change is accompanied by a progressive decrease in the content of incompatible elements, light-REE enrichments and elevation of the ridge that are similar to those observed south of the Azores and Iceland hotspots. Pillow basalts and glasses collected along the esternmost part of the Mohns Ridge (450 to 675 km east of Jan Mayen) have low K2O, TiO2, and P2O5 contents, light-REE depleted patterns relative to chondrites, and Mg/(Mg+Fe2+) ratios between 0.64 and 0.60. Pillow basalts and glasses from the Knipovich Ridge have similar (Mg/Mg+Fe2+) ratios, but along the entire ridge have slightly higher concentrations of incompatible elements and chondritic to slightly light-REE enriched patterns. The incompatible element enrichment increases slightly northward. Plagioclase phenocrysts show normal and reverse zoning on all parts of the ridge whereas olivines are unzoned or show only weak normal zoning. Olivine-liquid equilibrium temperatures are calculated to be in the range of 1,060–1,206° C with a mean around 1,180° C.

Rocks and glasses collected on the Jan Mayen Platform are compositionally similar to Jan Mayen volcanic products, suggesting that off-ridge alkali volcanism on the Jan Mayen Platform is more widespread than so far suspected. There is also evidence to suggest that the alkali basalts from the Jan Mayen Platform are derived from deeper levels and by smaller degrees of partial melting of a mantle significantly more enriched in light-REE and other incompatible elements than are the tholeiitic basalts from the Eastern Mohns and Knipovich Ridge. The possibility of the presence of another hitherto unsuspected enriched mantle region north of 77° 30′ N is also briefly considered.

It remains uncertain whether geochemical gradients revealed in this study reflect: (1) the dynamics of mixing during mantle advection and magma emplacement into the crust along the Mid-Atlantic Ridge (MAR) spreading axis, (e.g. such as in the mantle plume — large-ion-lithophile element depleted asthenosphere mixing model previously proposed); or (2) a horizontal gradation of the mantle beneath the MAR axis similar to that observed in the overlying crust; or (3) a vertical gradation of the mantle in incompatible elements with their contents increasing with depth and derivations of melts from progressively greater depth towards the Jan Mayen Platform.

This is a preview of subscription content, access via your institution.

References

  1. Ando A, Kurasawa T, Ohmori T, Takeda E (1974) Compilation of data on the GSJ geochemical reference sample JG-1 granodiorite and JB-1 basalt. Geochim J 8:175–192

    Google Scholar 

  2. Arth JC (1976) Behavior of trace elements during magmatic processes — a summary of theoretical models and their applications. J Res US Geol Surv 4:41–47

    Google Scholar 

  3. Aumento F (1968) The Mid-Atlantic Ridge near 45°N, II. Basalts from the area of Confedereration Peak. Can J Earth Sci 5:1–21

    Google Scholar 

  4. Bender JF, Hodges FN, Bence AE (1978) Petrogenesis of basalts from the project FAMOUS area: experimental study from 0 to 15 kbars. Earth Planet Sci Lett 41:277–302

    Google Scholar 

  5. Brooks CK, Jakobsson SP (1974) Petrochemistry of the volcanic rocks of the North Atlantic Ridge system. In: Kristiansson L (ed) Geodynamics of Iceland and the North Atlantic area. D Reidel, Dordrecht, 139–154

    Google Scholar 

  6. Campsie J, Bailey JC, Dittmer F (1973) Chemistry of tholeiites from the Reykjanes Ridge and Charlie Gibbs Fracture Zone. Nature Phys Sci 244:71–73

    Google Scholar 

  7. Clague DA, Fish MR, Bence AE (1980) Mineral chemistry of basalts from Ojin, Nintoku, and Suiko Seamounts, leg 55 DSDP. Initial Reports of the Deep Sea Drilling Project, vol 55, pp 607–637

    Google Scholar 

  8. Cox KG, Bell JD (1972) A crystal fractionation model for basaltic rocks of the New Georgia Group, British Solmon Islands. Contrib Mineral Petrol 37:1–13

    Google Scholar 

  9. Dittmer F, Fine S, Rasmussen M, Bailey JC, Campsie J (1975) Dredged basalts from the mid-ocean ridge north of Iceland. Nature 254:298–301

    Google Scholar 

  10. Fawcett JJ, Brooks CK, Rucklidge JC, Gasparrini EL (1973) Chemical petrology of Tertiary flood basalts from the Scoresby Sund area. Meddr Grønland Bd 195, Nr 6:1–54

    Google Scholar 

  11. Feden RH, Vogt PR, Fleming HS (1979) Magnetic and bathymetric evidence for the “Yermak hot spot” northwest of Svalbard in the Arctic Basin. Earth Planet Sci Lett 44:18–38

    Google Scholar 

  12. Frey FA, Bryan WB, Thompson G (1974) Atlantic Ocean floor: geochemistry and petrology of basalts from Legs 2 and 3 of the Deep Sea Drilling Project. J Geophys Res 79:5507–5527

    Google Scholar 

  13. Frey FA, Green DH, Roy SD (1978) Integrated models of basalt petrogenesis: a study of quartz tholeiites to olivine melilitites from South Eastern Australia utilizing geochemical and experimental petrological data. J Petrol 19:463–513

    Google Scholar 

  14. Goles GG (1975) Basalts of unusual composition from the Chyulu Hills, Kenya Lithos 8:47–58

    Google Scholar 

  15. Greenland LP (1970) An equation for trace element distribution during magmatic crystallization. Am Mineral 55:455–465

    Google Scholar 

  16. Haggerty SE (1976) Opaque mineral oxides in terrestrial igneous rocks. In: Rumble III D (ed) Oxide Minerals, Mineral Soc Am Short Course Notes, vol 3, ppHg-101–300

  17. Hanson GN (1977) Geochemical evolution of the suboceanic mantle. J Geol Soc London 134:235–253

    Google Scholar 

  18. Hekinian R, Moore JG, Bryan WB (1976) Volcanic rocks and processes of the Mid-Atlantic Ridge rift valley near 36°49′N. Contrib Mineral Petrol 58:83–110

    Google Scholar 

  19. Imsland P (1980) The petrology of the volcanic island Jan Mayen Arctic Ocean. Nordic Vole Inst Iceland, Int Rep 8003:1–501

    Google Scholar 

  20. Irvine TN (1977a) Definition of primitive liquid compositions for basic magmas. Carnegie Inst Wash Yearb 76:454–461

    Google Scholar 

  21. Irvine TN (1977b) Relative variations of substituting chemical components in petrologic fractionation processes. Carnegie Inst Wash Yearb 76:539–541

    Google Scholar 

  22. Irving AJ (1978) A review of experimental studies of crystal/liquid trace element partitioning. Geochim Cosmochim Acta 42:743–770

    Google Scholar 

  23. Johnson L, Monahan D (1979) Geomorphology of the Arctic Basin and adjacent continental margins. EOS 60:372

    Google Scholar 

  24. Kurz MD, Jenkins WJ, Schilling JG, Hart SR (1982) Helium isotopic variations in the mantle beneath the central North Atlantic Ocean. Earth Planet Sci Lett 36:133–156

    Google Scholar 

  25. LeMaitre RW (1962) Petrology of volcanic rocks. Gough Island, South Atlantic. Geol Soc Am Bull 73:1309–1340

    Google Scholar 

  26. Lussiaa-Berdon-Polve M, Vidal P (1973) Initial strontium isotopic compositions of volcanic rocks from Jan Mayen and Spitsbergen. Earth Planet Sci Lett 18:333–338

    Google Scholar 

  27. Maaloe S, Aoki K-i (1977) The major element composition of the upper mantle estmated from the composition of lherzolites. Contrib Mineral Petrol 63:161–173

    Google Scholar 

  28. Malod J, Mascle J (1975) Structures geologiques de la Marge Continentale a l'Ouest du Spitsberg. Marine Geophys Res 2:215–229

    Google Scholar 

  29. McMaster RL, Schilling JG, Pinet PR (1977) Plate boundary within Tjornes fracture zone on northern Iceland's insular margin. Nature 269:663–668

    Google Scholar 

  30. Melson WG, Vallier TL, Wright TL, Byerly G, Nelen J (1976) Chemical diversity of abyssal volcanic glass erupted along Pacific, Atlantic, and Indian Ocean sea-floor spreading centers. In: The Geophysics of the Pacific Ocean Basin and Its Margin. Am Geophys Union, Washington DC, pp 351–367

    Google Scholar 

  31. Mysen BO, Boettcher AL (1975a) Melting of a hydrous mantle: I. Phase relations of natural peridotite at high pressures and temperatures with controlled activities of water, carbon dioxide, and hydrogen. J Petrol 16:520–546

    Google Scholar 

  32. Mysen BO, Boettcher AL (1975b) Melting of a hydrous mantle: II. Geochemistry of crystals and liquids formed by anatexis of mantle peridotite at high pressures and high temperatures as a function of controlled activities of water, hydrogen, and carbon dioxide. J Petrol 16:549–599

    Google Scholar 

  33. Mysen BO, Kushiro I (1977) Compositional variation of coexisting phases with degree of melting of peridotite in the upper mantle. Am Mineral 62:843–865

    Google Scholar 

  34. Nielsen TFD (1978) The Tertiary dike swarms of the Kangerdlugssuaq area, East Greenland. Contrib Mineral Petrol 67:63–78

    Google Scholar 

  35. O'Nions RK, Pankhurst RJ (1974) Petrogenetic significance of isotope and trace element variations in volcanic rocks from the Mid-Atlantic. J Petrol 15:603–634

    Google Scholar 

  36. Pearce JA (1976) Statistical analysis of major element patterns in basalts. J Petrol 17:15–43

    Google Scholar 

  37. Pedersen S, Larsen O, Hall N, Campsie J, Bailey JC (1976) Strontium isotope and lithophile element values from the submarine Jan Mayen province. Bull Geol Soc Demn 25:15–20

    Google Scholar 

  38. Perry RK, Fleming HS, Cherkis NZ, Feden RH, Vogt PR (1980) Bathymetry of the Norwegian-Greenland and western Barents seas. Naval Res Lab Washington DC

    Google Scholar 

  39. Presnall DC, Dixon SA, Dixon JR, O'Donnell TH, Brenner NL, Schrock RL, Dycus DW (1978) Liquidus phase relations on the join diopside-forsterite-anorthite from 1 atm to 20 kbar: their bearing on the generation and crystallization of basaltic magma. Contrib Mineral Petrol 66:203–220

    Google Scholar 

  40. Presnall DC, Dixon JR, O'Donnell TH, Dixon SA (1979) Generation of mid-ocean ridge tholeiites. J Petrol 20:3–35

    Google Scholar 

  41. Schilling J-G (1973) Iceland mantle plume: geochemical study of Reykjanes Ridge. Nature 242:565–571

    Google Scholar 

  42. Schilling JG (1976) Petrochemical variations along the Mid-Atlantic Ridge from 29°N to 73°N. Trans Am Geophys Union 57:408

    Google Scholar 

  43. Schilling JG, Anderson RN, Vogt P (1976) Rare earth, Fe and Ti variations along the Galapagos spreading centre, and their relations along the Galapagos mantle plume. Nature 26:108–113

    Google Scholar 

  44. Schilling JG, Sigurdsson H (1979) Thermal minima along the axis of the Mid-Atlantic Ridge. Nature 282:370–375

    Google Scholar 

  45. Schilling JG, Zajac M, Evans R, Johnston T, White W, Devine JD, Kingsley R (1983) Petrologic and geochemical variations along the Mid-Atlantic Ridge from 29°N to 73°N. Am J Sci (in press)

  46. Schmitt RA, Smith RH, Olehy DA (1964) Rare-earth, yttrium and scandium abundances in meteoritic and terrestrial matter — II. Geochim Cosmochim Acta 28:67–86

    Google Scholar 

  47. Shaw DM (1970) Trace element fractionation during anatexis. Geochim Cosmochim Acta 34:237–243

    Google Scholar 

  48. Sigurdsson H (1981) First-order major element variations in basalt glasses from the Mid-Atlantic Ridge: 29°N to 73°N. J Geophys Res 86:9483–9502

    Google Scholar 

  49. Sigurdsson H, Brown GM (1970) An unusual enstatite-forsterite basalt from Kolbeinsey Island, north of Iceland. J Petrol 11:205–220

    Google Scholar 

  50. Sigurdsson H, Schilling JG (1976) Spinels in Mid-Atlantic Ridge basalts, chemistry and occurrence. Earth Planet Sci Lett 29:7–20

    Google Scholar 

  51. Sparks RSJ, Meyer P, Sigurdsson H (1980) Density variations amongst mid-ocean ridge basalts: implications for magma mixing and the scarcity of primitive lavas. Earth Planet Sci Lett 46:419–430

    Google Scholar 

  52. Stosch HG (1982) Rare earth element partitioning between minerals from anhydrous spinel peridotite xenoliths. Geochim Cosmochim Acta 46:793–811

    Google Scholar 

  53. Stolper E, Walker D (1980) Melt density and the average composition of basalt. Contrib Mineral Petrol 74:1–12

    Google Scholar 

  54. Talwani M, Eidholm O (1977) Evolution of the Norwegian-Greenland Sea. Geol Soc Am Bull 88:969–999

    Google Scholar 

  55. Vogt PR, Perry RK, Feden RH, Fleming HS, Cherkis NZ (1981) The Greenland-Norwegian Sea and Iceland environment: Geology and geophysics, In: The Ocean Basins and Margins, vol. 5, Eds. Nairn AEM, Churkin M Jr, and Stheli IG, Plenum Publishing Co: 493–598

  56. Wagonner DG, Vollmer R, Schilling JG (1981) Isotopic and trace element variations along the Mohns and Knipovich Ridges. Trans Am Geophys Union 62:423

    Google Scholar 

  57. Walker D, DeLong SE (1981) Soret separation of mid-ocean ridge basalt magma. Contrib mineral Petrol 79:231–240

    Google Scholar 

  58. Walker D, Shibata T, DeLong SE (1979) Abyssal tholeiites from the Oceanographer Fracture Zone. Contrib Mineral Petrol 70:111–125

    Google Scholar 

  59. Weigand PW (1972) Bulk-rock and mineral chemistry of recent Jan Mayen basalts. Norsk Polarinst Årbok 1970:42–52

    Google Scholar 

  60. Weigand PW, Brunfelt AO, Heier KS, Sundvoll B, Steinnes E (1972) Geochemistry of alkali olivine basalts from an eruption on Jan Mayen. Nature Phys Sci 235:31–33

    Google Scholar 

  61. White WM, Schilling JG (1978) The nature and origin of geochemical variations in Mid-Atlantic Ridge basalts from the central North Atlantic. Geochim Cosmochim Acta 42:1501–1516

    Google Scholar 

  62. Wood DA, Tarney J, Varet J, Saunders AD, Bougault H, Joron JL, Treuil M, Cann JR (1979) Geochemistry of basalts drilled in the North Atlantic by IPOD leg 49: implications for mantle heterogeneity. Earth Planet Sci Lett 42:77–97

    Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Else-Ragnhild Neumann.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Neumann, ER., Schilling, JG. Petrology of basalts from the Mohns-Knipovich Ridge; the Norwegian-Greenland Sea. Contr. Mineral. and Petrol. 85, 209–223 (1984). https://doi.org/10.1007/BF00378101

Download citation

Keywords

  • Olivine
  • Nepheline
  • Mantle Plume
  • Incompatible Element
  • Pillow Basalt