Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Primary basalts and magma genesis

II. Snake River Plain, Idaho, U.S.A.

  • 178 Accesses

  • 65 Citations

Abstract

The Pliocene-Holocene lavas of the Snake River Plain, Idaho, U.S.A., have a bimodal composition range, consisting predominantly of basalts (olivine-tholeiites), with subordinate intercalated tholeiitic andesites but with very few analyses falling between these groups. The more-magnesian of the tholeiitic andesites contain more total Fe, alkalis, TiO2 and P2O5 but less SiO2 than the less-magnesian basalts. Derivation of the tholeiitic andesites from the basalts by low-pressure fractional crystallization or by major-element crustal contamination does not seem possible, although some minor-element exchange with ancient crust apparently has occurred. Two lavas, representative of the least-magnesian basalts and the most-magnesian tholeiitic andesites, respectively, have been subjected to anhydrous experimental studies within their melting ranges at pressures up to 35kb. Both appear to show four-phase points on their liquidi at about 8kb and these are thought to have genetic significance. Microprobe analyses of the interstitial glasses in partially-crystalline runs on the basalt between 8 and 12kb show that these reproduce all the characteristic features of the Snake River Plain most-magnesian tholeiitic andesites, notably their reduced Si-saturation. The compositions of the most Mg-rich Snake River Plain basalts are such that they may perhaps be primary magmas, produced by partial fusion of a relatively Fe-rich spinel-lherzolite upper mantle at 50 to 60km depth; a proposal which accords well with the geophysics of this currently-active region. Partial crystallization of batches of this magma, delayed during ascent within the crust at depths of about 30 km, is thought to have given rise to the tholeiitic andesites.

This is a preview of subscription content, log in to check access.

References

  1. Armstrong, R.L., Leeman, W.P.: K-Ar chronology of Snake River Plain, Idaho. Abstr. with Programs (Geol. Soc. Amer.) 3, 366 (1971)

  2. Blackwell, D.D.: The thermal structure of the continental crust. Am. Geophys. Union, Monograph 14, 169–184 (1971)

  3. Buddington, A.F., Lindsley, D.H.: Iron-titanium oxide minerals and synthetic equivalents. J. Petrol, 5, 310–357 (1964)

  4. Bullard, F.M., Rylander, D.L.: Holocene volcanism in Craters of the Moon National Monument and adjacent areas, South-Central Idaho. Abstr. with Programs (Geol. Soc. Amer.) 2, 273 (1970)

  5. Cawthorn, R.G., Ford, C.E., Biggar, G.M., Bravo, M.S., Clarke, D.B.: Determination of the liquid composition in experimental samples: discrepancies between microprobe analysis and other methods. Earth Planet. Sci. Lett. 21, 1–5 (1973)

  6. Christiansen, R.L., Lipman, P.W.: Cenozoic volcanism and plate-tectonic evolution of the Western United States. II Late Cenozoic. Phil. Trans. Roy. Soc. London A. 271, 249–284 (1972)

  7. Green, D.H., Hibberson, W.: Experimental duplication of conditions of precipitation of high-pressure phenocrysts in a basaltic magma. Phys. Earth Planet. Int. 3, 247–254 (1970)

  8. Hamilton, W., Myers, W.B.: Cenozoic tectonics of the western United States. Rev. Geophys. 4, 509–550 (1966)

  9. Hart, S.R., Schilling, J.-G., Powell, J.L.: Basalts from Iceland and along the Reykjanes Ridge: Sr isotope geochemistry. Nature. Phys. Sci. 246, 104–107 (1973)

  10. Hill, D.P.: Gravity and crustal structure in the western Snake River Plain, Idaho. J. Geophys. Res. 68, 5807–5819 (1963)

  11. Hill, D.P., Pakiser, L.C.: Seismic-refraction study of crustal structure between the Nevada Test Site and Boise, Idaho Bull. Geol. Soc. Am. 78, 685–704 (1967)

  12. Irvine, T.N., Baragar, W.R.A.: A guide to the chemical classification of the common volcanic rocks. Canad. J. Earth Sci. 8, 523–548 (1971)

  13. La Fehr, T.R., Pakiser, L.C.: Gravity, volcanism and crustal deformation in the eastern Snake River Plain, Idaho. U.S. Geol. Surv. Profess. Papers 450-D, D76-D78 (1962)

  14. Leeman, W.P., Manton, W.I.: Strontium isotopic composition of basaltic lavas from the Snake River Plain, southern Idaho. Earth Planet. Sci. Lett. 11, 420–434 (1971)

  15. Leeman, W.P., Manton, W.I.: Lead isotopic composition of Snake River Basalts, Idaho Eos 53, 277 (1972)

  16. Leeman, W.P., Rogers, J.J.W.: Late Cenozoic alkali-olivine basalts of the Basin-Range Province, USA. Contr. Mineral. and Petrol. 25, 1–24 (1970)

  17. Maaløe, S.: Temperature and pressure relations of ascending primary magmas. J. Geophys. Res. 78, 6877–6886 (1973)

  18. Malde, H.E.: Fault zone along northern boundary of western Snake River Plain, Idaho. Science, 130, 272 (1959)

  19. Malde, H.E., Powers, H.A.: Upper Cenozoic stratigraphy of Western Snake River Plain, Idaho. Bull Geol. Soc. Am. 73, 1197–1219 (1962)

  20. Morgan, W.J.: Plate motions and deep mantle convection. Mem. Geol. Soc. Am. 132, 7–22 (1972)

  21. Muehlenbachs, K., Stone, G.T.: Oxygen isotope compositions of some basaltic lavas from the Snake River Plain. Carnegie Inst. Wash. Yearbook 72, 598–601 (1973)

  22. O'Hara, M.J.: Non-primary magmas and dubious mantle plume beneath Iceland. Nature 243, 507–508 (1973)

  23. O'Nions, R.K., Grönvold, K.: Petrogenetic relationships of acid and basic rocks in Iceland: Srisotopes and rare-earth elements in late and postglacial volcanics. Earth Planet. Sci. Lett. 19, 397–409 (1973)

  24. Prinz, M.: Idaho Rift System, Snake River Plain, Idaho. Bull. Geol. Soc. Am. 81, 941–947 (1970)

  25. Powers, H.A.: A distinctive chemical characteristic of Snake River basalts of Idaho. U.S. Geol. Surv. Profess. Papers 400-B, B298 (1960)

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

  27. Schilling, J.-G.: Iceland mantle plume. Nature 246, 141–143 (1973b)

  28. Schilling, J.-G., Noe-Nygaard, A.: Faeroe-Iceland plume: rare-earth evidence. Earth Planet. Sci. Lett. 24, 1–14 (1974)

  29. Smith, R.B., Sbar, M.L.: Contemporary tectonics and seismicity of the western United States with emphasis on the Intermountain Seismic Belt. Bull. Geol. Soc. Am. 85, 1205–1218 (1974)

  30. Stearns, H.T., Crandall, L., Steward, W.G.: Geology and groundwater resources of the Snake River Plain in south-eastern Idaho. U.S. Geol. Surv. Water-Supply Pap. 774, 1–268 (1938)

  31. Stone, G.T.: Petrology of upper Cenozoic basalts of the western Snake River Plain. Unpubl. Ph.D. thesis, Univ. of Colorado (1967)

  32. Thompson, R.N.: The 1-atmosphere melting patterns of some basaltic volcanic series. Am. J. Sci. 272, 901–932 (1972a)

  33. Thompson, R.N.: Melting behavior of two Snake River lavas at pressures up to 35 kb. Carnegie Inst. Wash. Yearbook 71, 406–410 (1972b)

  34. Thompson, R.N.: Evidence for a chemical discontinuity near the basalt — “andesite” transition in many anorogenic volcanic suites. Nature 236, 106–110 (1972c)

  35. Thompson, R.N.: One-atmosphere melting behaviour and nomenclature of terrestrial lavas. Contr. Mineral. and Petrol. 41, 197–204 (1973a)

  36. Thompson, R.N.: Titanian chromite and chromian titanomagnetite from a Snake River Plain basalt, a terrestrial analogue to lunar spinels. Am. Mineralogist 58, 826–830 (1973b)

  37. Thompson, R.N.: Primary basalts and magma genesis. I. Skye, North-West Scotland. Contr. Mineral. and Petrol. 45, 317–341 (1974a)

  38. Thompson, R.N.: Some high-pressure pyroxenes. Mineral. Mag. 39, 768–787 (1974b)

  39. Thompson, R.N.: The 1-atmosphere liquidus oxygen fugacities of some tholeiitic intermediate, alkalic and ultra-alkalic lavas. Am. J. Sci., in press (1975a)

  40. Thompson, R.N.: Is upper mantle phosphorus contained in sodic garnets? Earth Planet. Sci. Lett., in press (1975b)

  41. Thompson, R.N., Esson, J., Dunham, A.C.: Major element chemical variation in the Eocene lavas of the Isle of Skye, Scotland. J. Petrol. 13, 219–253 (1972)

  42. Thompson, R.N., Kushiro, I.: The oxygen fugacity within graphite capsules in piston — cylinder apparatus at high pressures. Carnegie Inst. Wash. Yearbook 71, 615–616 (1972)

  43. Tilley, C.E., Thompson, R.N.: Melting and crystallization relations of the Snake River Basalts of Southern Idaho, U.S.A. Earth Planet, Sci. Lett. 8, 79–92 (1970)

  44. Treuil, M., Varet, J.: Critères volcanologiques, pétrologiques et géochemiques de la genèse et de la différenciation des magmas basaltiques: exemple de l'Afar. Bull. Soc. Géol. France 15, 506–540 (1973)

  45. Wager, L.R.: The major element variation of the layered series of the Skaergaard intrusion and a re-estimation of the average composition of the hidden layered series and of the successive residual magmas. J. Petrol. 1, 364–398 (1960)

  46. Wager, L.R., Deer, W.A.: Geological investigations in East Greenland. Part III. The petrology of the Skaergaard intrusion, Kangerdlugssuaq, East Greenland. Medd. Grønland 105, No. 4, 1–352 (1939)

  47. Wager, L.R. Vincent, E.A.: Ferrodiorite from the Isle of Skye. Mineral. Mag. 33, 26–36 (1962)

  48. Weertman, J.: Theory of water-filled crevasses in glaciers applied to vertical magma transport beneath oceanic ridges. J. Geophys. Res. 76, 1171–1183 (1971)

  49. Wright, T.L., Doherty P.C.: A linear programming and least squares computer method for solving petrologic mixing problems. Bull. Geol. Soc. Am. 81, 1995–2008 (1970)

  50. Yoder, H.S., Jr.: Calcalkaline andesites: experimental data bearing on the origin of their assumed characteristics. In: McBirney, A.R., ed., Proceedings of the Andesite Conference. Oregon Dept. Geol. Mineral Ind. Bull. 65, 77–89 (1969)

  51. Yoder, H.S., Jr., Tilley, C.E.: Origin of basalt magmas: an experimental study of natural and synthetic rock systems. J. Petrol. 3, 342–532 (1962)

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Thompson, R.N. Primary basalts and magma genesis. Contr. Mineral. and Petrol. 52, 213–232 (1975). https://doi.org/10.1007/BF00457295

Download citation

Keywords

  • TiO2
  • Fractional Crystallization
  • Genetic Significance
  • Crustal Contamination
  • Melting Range