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Geochemistry of the Shuksan greenschists and blueschists, North Cascades, Washington: Variably fractionated and altered metabasalts of oceanic affinity

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Abstract

The Shuksan schist comprises a structurally coherent, metabasaltic member of the Easton Formation, the uppermost allochthon (Shuksan thrust plate) in the thrust system of the western North Cascades of Washington State. Late Jurassic metamorphism at moderately high P/T produced interlayering of actinolite-bearing greenschist assemblages with blue amphibole-bearing rocks. Major and trace element analyses of twelve greenschist and blueschist samples have been used to establish similarities between the basaltic protolith and moderately to strongly fractionated Type I MORB, to distinguish the effects of seafloor alteration superimposed on the primary igneous chemistry, and to evaluate the origin and nature of the chemical controls which produced the two mineral assemblages.

The twelve analyzed samples exhibit moderate to strong LREE depletion, and characteristically low concentrations of other non-labile trace elements such as Nb, Th and Hf. The highly to moderately incompatible elements Ti, P, Nb, Zr, Hf, Y, Sc, and the REE vary by factors of 1.5 to 3.5 within the suite in a systematic pattern, increasing smoothly with increasing total iron. The relative enrichments of these elements are inversely proportional to bulk partition coefficients estimated for fractionation of basaltic magmas. The magnitude of the negative europium anomaly increases with overall incompatible element enrichment. These variations are consistent with the production of a wide spectrum of compositions by different degrees of low pressure fractionation of similar Type I MORB parent magmas.

The concentrations of Sr, Rb, Na, and K vary irregularly and do not correlate with the non-labile trace elements. K and Rb are substantially elevated over typical MORB values in most samples and exhibit a consistently lower ratio (K/Rb=400 vs 1000) than fresh MORB. Concentrations of these four elements are believed to have been modified by low temperature seafloor alteration (pre-metamorphic) characterized by the formation of K-rich celadonitic clays, palagonite and minor potassium feldspar.

The critical chemical variables that control the occurrence of actinolite and blue amphibole in the Shuksan schists are total iron, Fe2O3-content and Na/Ca (all high in blueschists). The chemical features were largely established by magmatic processes and inherited from the igneous parent rocks; the chemically more evolved samples are blueschists. The Fe2O3-content and Na/Ca, however, may be modified during alteration, rendering initial bulk compositions near the chemical boundary susceptible to changes which may shift rock compositions from one compatibility field to the other. Heterogeneous alteration of pillow lavas and other fragmental deposits, followed by intense flattening during metamorphism, provides a mechanism for generating blueschists and greenschists interlayered on the cm scale.

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References

  • Armstrong RL (1980) Geochronometry of the Shuksan metamorphic suite, North Cascades, Washington. Geol Soc Am Abstr Progr 12:94

    Google Scholar 

  • Ashleman JC (1979) The geology of the western part of the Kachess Lake Quadrangle, Washington, M.S. Thesis, University of Washington, Seattle, pp 1–38

    Google Scholar 

  • Blanchard DP, Rhodes JM, Dungan MA, Rodgers KV, Donaldson CH, Brannon JC, Jacobs JW, Gibson EK (1976) The chemistry and petrology of basalts from Leg 37 of the Deep-Sea Drilling Project. J Geophys Res 81:4231–4246

    Google Scholar 

  • Böhlke JK, Honnorez J, Honnorez-Guerstein B-M, Muehlenbachs K, Petersen N (1981) Heterogeneous alteration of the upper oceanic crust: Correlation of rock chemistry, magnetic properties, and 0 isotope ratios with alteration patterns in basalts from 396B, DSDP. J Geophys Res 86(B9): 7935–7950

    Google Scholar 

  • Brigo L, Dal Piaz GV, Ferrario A (1976) Le mineralizzazioni cuprifero legati ai termini effusivi di alcuni compless: ofiolitici nell'area Mediterranea. Bol Assoc Miner Subalpina 13:352–371

    Google Scholar 

  • Brown EH (1974) Comparison of the mineralogy and phase relations of blueschists from the North Cascades, Washington, and greenschists from Otago, New Zealand. Bull Geol Soc Am 85:333–344

    Google Scholar 

  • Brown EH (1977) The crossite content of Ca-amphibole as a guide to pressure of metamorphism. J Petrol 18:53–72

    Google Scholar 

  • Brown EH, Bernardi ML, Christenson BW, Cruver JR, Haugerud RA, Rady PM, Sondergaard JB (1981) Metamorphic facies and tectonics in part of the Cascade Range and Puget Lowland of northwestern Washington. Bull Geol Soc Am 92:170–178

    Google Scholar 

  • Bryan WB, Thompson G, Frey FA, Dickey JS (1976) Inferred geologic settings and differentiation in basalts from the Deep-Sea Drilling Project. J Geophys Res 81:4285–4304

    Google Scholar 

  • Bryan WB, Thompson G, Ludden JN (1981) Compositional variation in normal MORB from 22–25° N: Mid-Atlantic Ridge and Kane Fracture Zone. J Geophys Res 86(B12):11815–11836

    Google Scholar 

  • Cann JR (1979) Metamorphism in the ocean crust. In: Talwani M, Harrison CG, Hayes DE (eds) Deep drilling results in the Atlantic Ocean: Ocean Crust — Maurice Ewing Series 2. American Geophysical Union, Washington, DC, pp 230–238

    Google Scholar 

  • Coish RA (1977) Ocean floor metamorphism in the Betts Cove ophiolite, Newfoundland. Contrib Mineral Petrol 60:255–270

    Google Scholar 

  • Donnelly TW, Thompson G, Robinson PT (1979) Very-low-temperature hydrothermal alteration of the oceanic crust and the problem of fluxes of potassium and magnesium. In: Talwani M, Harrison CG, Hayes DE (eds) Deep drilling results in the Atlantic Ocean: Ocean Crust — Maurice Ewing Series 2. American Geophysical Union, Washington, DC, pp 369–382

    Google Scholar 

  • Dungan MA, Rhodes JM, Long PE, Blanchard DP, Brannon JC, Rodgers KV (1978) Petrology and chemistry of basaltic rocks from Hole 396B IPOD/DSDP Leg 46. In: Dmitriev L (ed) Initial reports of the deep sea drilling project, Leg 46. U.S. Government Printing Office, Washington, DC, pp 89–114

    Google Scholar 

  • Emmerman R, Puchelt H (1980) Major and trace-element chemistry of basalts from holes 417D and 418A, DSDP Legs 51–53. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 987–1000

    Google Scholar 

  • Evans BW, Trommsdorff V, Goles GG (1981) Geochemistry of high-grade eclogites and metarodingites from the Central Alps. Contrib Mineral Petrol 76:301–311

    Google Scholar 

  • Gill JB (1981) Orogenic andesites and plate tectonics. Springer, Berlin-Heidelberg-New York

    Google Scholar 

  • Hart SR (1969) K, Rb, Cs contents and K/Rb, K/Cs ratios of fresh and altered submarine basalts. Earth and Planet Sci Lett 6:295–303

    Google Scholar 

  • Hart SR, Staudigel H (1980) Oceanic crust — seawater interaction: Sites 417 and 418. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1169–1176

    Google Scholar 

  • Haugerud RA, Morrison ML, Brown EH (1981) Structural and metamorphic history of the Shuksan metamorphic suite in the Mount Watson and Gee Point areas, North Cascades, Washington. Bull Geol Soc Amer 92:374–383

    Google Scholar 

  • Hellman PL, Henderson P (1977) Are rare earths mobile during spilitization? Nature 267:38–40

    Google Scholar 

  • Hellman PL, Smith RE, Henderson P (1977) Rare earth element investigation of the Cliefdon Outcrop, N.S.W., Australia. Contrib Mineral Petrol 65:155–164

    Google Scholar 

  • Humphris S, Thompson G (1978a) Hydrothermal alteration of oceanic basalts by seawater. Geochim Cosmochim Acta 42:107–125

    Google Scholar 

  • Humphris S, Thompson G (1978b) Trace element mobility during hydrothermal alteration of oceanic basalts. Geochim Cosmochim Acta 42:127–136

    Google Scholar 

  • Humphris SE, Thompson RN, Marriner GF (1980) The mineralogy and geochemistry of Basalt weathering, Holes 417A and 418A. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1201–1218

    Google Scholar 

  • Hynes A (1980) Carbonitization and mobility of Ti, Y, and Zr in Ascot Formation metabasalts, SE Quebec. Contrib Mineral Petrol 75:79–87

    Google Scholar 

  • Jacobs JW, Korotev RL, Blanchard DP, Haskin LA (1977) A well tested procedure for instrumental neutron activation analysis of silicate rocks and minerals. J Radioanal Chem 40:93–114

    Google Scholar 

  • Laird J, Albee AL (1981a) High-pressure metamorphism in mafic schist from northern Vermont. Am J Sci 281:97–216

    Google Scholar 

  • Laird J, Albee AL (1981b) Pressure, temperature, and time indicators in mafic schist: their application to reconstructing the polymetamorphic history of Vermont. Am J Sci 281:127–175

    Google Scholar 

  • Leake BE (1978) Nomenclature of amphiboles. Am Min 63:1023–1052

    Google Scholar 

  • Maxwell JA (1968) Rock and mineral analysis. Interscience, New York

    Google Scholar 

  • McKay GA, Weill DF (1977) KREEP petrogenesis revisited. Proc Eighth Lun Sci Conf, pp 2339–2355

  • Melson WG, Byerly GR, Nelen JA, O'Hearn T, Wright TL, Vallier T (1976) A catalog of the major element chemistry of abyssal volcanic glasses. In: Mason B (ed) Mineral science investigations of the Smithsonian Institution. Contrib Earth Sci 19:31–60

  • Menzies M, Blanchard D, Jacobs J (1977) Rare earth and trace element geochemistry of metabasalts from the Point Sal ophiolite, California. Earth Planet Sci Lett 37:203–215

    Google Scholar 

  • Menzies M, Seyfried W, Blanchard D (1979) Experimental evidence of rare-earth element immobility in greenstones. Nature 282:398–399

    Google Scholar 

  • Mevel C (1980) Mineralogy and chemistry of secondary phases in low temperature altered basalts from deep sea drilling project. Legs 51, 52, and 53. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1299–1318

    Google Scholar 

  • Misch P (1959) Sodic amphiboles and metamorphic facies in Mount Shuksan belt, northern Cascades, Washington. (Abstr.) Bull Geol Soc Amer 70:1736–1737

    Google Scholar 

  • Misch P (1966) Tectonic evolution of the Northern Cascades of Washington State. In: Gunning HC (ed) Tectonic history and mineral deposits of the Western Cordillera. Canadian Institute of Mining and Metallurgy, Special Vol 8, pp 101–148

  • Misch P (1969) Paracrystalline microboudinage of zoned grains and other criteria for synkinematic growth of metamorphic minerals. Am J Sci 267:43–63

    Google Scholar 

  • Morrison MA (1978) The use of ‘immobile’ trace elements to distinguish the paleotectonic affinities of metabasalts: applications to the Paleocene basalts of Mull and Skye, northwest Scotland. Earth Planet Sci Lett 39:407–416

    Google Scholar 

  • Norrish K, Chappell BW (1967) X-ray fluorescence spectrography. In: Zussman L (ed) Physical methods in determinative mineralogy. Academic Press, New York, pp 161–214

    Google Scholar 

  • Norrish K, Hutton JT (1969) An accurate X-ray spectrographic method for the analysis of a wide range of geologic samples. Geochim Cosmochim Acta 33:431–453

    Google Scholar 

  • Papike JJ, Cameron KL, Baldwin K (1974) Amphiboles and pyroxenes: characterization of Other than quadrilateral components and estimates of ferric iron from microprobe data. Geol Soc Am Abstr Programs 6:1053–1054

    Google Scholar 

  • Pearce JA, Cann JR (1971) Ophiolite origin investigated by discriminant analysis using Ti, Zr, and Y. Earth Planet Sci Lett 12:333–349

    Google Scholar 

  • Pearce JA, Cann JR (1973) Tectonic setting of basic volcanic rocks determined using trace element analyses. Earth Planet Sci Lett 19:290–300

    Google Scholar 

  • Pearce JA, Norry MJ (1979) Petrogenetic implications of Ti, Zr, Y, and Nb variations in volcanic rocks. Contrib Mineral Petrol 69:33–47

    Google Scholar 

  • Prichard RG (1980) Alterations of basalts from deep sea drilling project, Legs 51, 52, and 53, Holes 317A and 418A. In: Donnelly TW (ed). Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1185–1200

    Google Scholar 

  • Reynolds RC (1967) Estimation of mass absorption coefficients by Compton scattering: Improvements and extensions of the method. Am Mineral 48:1133–1143

    Google Scholar 

  • Rhodes JM, Blanchard DP, Rodgers KV, Jacobs JW, Brannon JC (1976) Petrology and chemistry of basalts from the Nazca Plate, 2, Major and trace element chemistry. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Leg 34. U.S. Government Printing Office, Washington, DC, pp 239–244

    Google Scholar 

  • Rhodes JM, Blanchard DP, Dungan MA, Rodgers KV, Brannon JC (1978) Chemistry of basalts from Leg 45 of the deep sea drilling project. In: Melson WG (ed) Initial reports of the deep sea drilling project, Leg 45. U.S. Government Printing Office, Washington, DC, pp 447–459

    Google Scholar 

  • Rhodes JM, Dungan MA, Blanchard DP, Long PE (1979) Magma mixing at mid-ocean ridges: evidence from basalts near 22° N on the Mid-Atlantic ridge. Tectonophys 55:36–61

    Google Scholar 

  • Rusinov VL, Laputina IP, Muravitskaja BB, Zvjagin BB, Graduson BP (1980) Clay minerals in basalts from deep sea drilling project sites 417 and 418. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1265–1272

    Google Scholar 

  • Scott RB, Hajash A (1976) Initial submarine alteration of basaltic pillow lavas: A microprobe study. Am J Sci 276:480–501

    Google Scholar 

  • Smith GO (1903) The geology and physiography of central Washington, 9–39. In: Smith GO, Willis B (eds) Contributions to the geology of Washington: US Geol Survey Prof Paper 19, 101 p

  • Smith RE, Smith SW (1976) Comments on the use of Ti, Zr, Y, Sr, K, P, and Nb in classification of basaltic magma. Earth Planet Sci Lett 32:114–120

    Google Scholar 

  • Staudigel H, Frey FA, Hart SR (1980) Incompatible trace element geochemistry and 87/86 Sr in basalts and corresponding glasses and palagonites. In: Donnelly TW (ed) Initial reports of the deep sea drilling project, Legs 51, 52, 53. U.S. Government Printing Office, Washington, DC, pp 1137–1144

    Google Scholar 

  • Sun S-S, Nesbitt RW (1978) Petrogenesis of Archean ultrabasic and basic volcanics: Evidence from rare earth elements. Contrib Mineral Petrol 65:301–325

    Google Scholar 

  • Vance JA (1957) The geology of the Sauk River area in the northern Cascades of Washington (Ph.D. dissert.) University of Washington, Seattle

    Google Scholar 

  • Vance JA, Dungan MA, Blanchard DP, Rhodes JM (1980) Tectonic setting and trace element geochemistry of Mesozoic ophiolitic rocks in western Washington. Am J Sci 280-A: 359–388

    Google Scholar 

  • Vance JA, Miller RB (1981) The movement history of the Straight Creek fault. Geol Assoc Canada Prog and Abs Cordill Sect: 39–41

  • Winchester JA, Floyd PA (1976) Geochemical magma type discrimination: application to altered and metamorphosed basic igneous rocks. Earth Planet Sci Lett 28:459–469

    Google Scholar 

  • Wood PA, Gibson IL, Thompson RN (1976) Elemental mobility during zeolite facies metamorphism of the Tertiary basalts of Eastern Iceland. Contrib Mineral Petrol 55:241–254

    Google Scholar 

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Authors and Affiliations

  1. Department of Geological Sciences, Southern Methodist University, 75275, Dallas, TX, USA

    M. A. Dungan

  2. Department of Geological Sciences, University of Washington, 98195, Seattle, WA, USA

    J. A. Vance

  3. Curatorial Branch, SN2 NASA-Johnson Space Center, 77058, Houston, TX, USA

    D. P. Blanchard

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  1. M. A. Dungan
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  2. J. A. Vance
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  3. D. P. Blanchard
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Dungan, M.A., Vance, J.A. & Blanchard, D.P. Geochemistry of the Shuksan greenschists and blueschists, North Cascades, Washington: Variably fractionated and altered metabasalts of oceanic affinity. Contr. Mineral. and Petrol. 82, 131–146 (1983). https://doi.org/10.1007/BF01166608

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