Advertisement

Contributions to Mineralogy and Petrology

, Volume 113, Issue 3, pp 333–351 | Cite as

Petrology of the Chilliwack batholith, North Cascades, Washington: generation of calc-alkaline granitoids by melting of mafic lower crust with variable water fugacity

  • Jeffrey H. Tepper
  • Bruce K. Nelson
  • George W. Bergantz
  • Anthony J. Irving
Article

Abstract

Calc-alkaline granitoid rocks of the Oligocene-Pliocene Chilliwack batholith, North Cascades, range from quartz diorites to granites (57–78% SiO2), and are coeval with small gabbroic stocks. Modeling of major element, trace element, and isotopic data for granitoid and mafic rocks suggests that: (1) the granitoids were derived from amphibolitic lower crust having REE (rare-earth-element) and Sr-Nd isotopic characteristics of the exposed gabbros; (2) lithologic diversity among the granitoids is primarily the result of variable water fugacity during melting. The main effect of fH2O variation is to change the relative proportions of plagioclase and amphibole in the residuum. The REE data for intermediate granitoids (quartz diorite-granodiorite; Eu/Eu*=0.84–0.50) are modeled by melting with fH2O<1 kbar, leaving a plagioclase + pyroxene residuum. In contrast, data for leucocratic granitoids (leuco-granodiorites and granites; Eu/Eu* =1.0–0.54) require residual amphibole in the source and are modeled by melting with fH2O=2–3 kbar. Consistent with this model, isotopic data for the granitoids show no systematic variation with rock type (87Sr/86Sri =0.7033–0.7043; εNd(0)=+3.3 to +5.5) and overlap significantly with data for the gabbroic rocks (87Sr/86Sri =0.7034–0.7040; εNd(0)=+3.3 to +6.9). The fH2O variations during melting may reflect additions of H2O to the lower crust from crystallizing basaltic magmas having a range of H2O contents; Chillwack gabbros document the existence of such basalts. One-dimensional conductive heat transfer calculations indicate that underplating of basaltic magmas can provide the heat required for large-scale melting of amphibolitic lower crust, provided that ambient wallrock temperatures exceed 800°C. Based on lithologic and geochemical similarities, this model may be applicable to other Cordilleran batholiths.

Keywords

Lower Crust Mafic Rock Basaltic Magma Conductive Heat Transfer Quartz Diorite 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Allen JC, Boettcher AL (1978) Amphiboles in andesite and basalt, II: stability as a function of P-T-fH 2 O-fO 2. Am Mineral 63:1074–1087Google Scholar
  2. Arculus RJ, Wills KJA (1980) The petrology of plutonic blocks and inclusions from the Lesser Antilles Island Arc. J Petrol 21:743–799Google Scholar
  3. Arth JG (1976) Behavior of trace elements during magmatic processes-a summary of theoretical models and their applications. J Res US Geol Surv 4:41–47Google Scholar
  4. Arth JG, Barker F (1976) Rare-earth partitioning between hornblende and dacitic liquid and implications for the genesis of trondhjemitic-tonalitic magmas. Geology 4:534–536Google Scholar
  5. Bacon CR (1990) Calc-alkaline, shoshonitic, and primitive tholeiitic lavas from monogenetic volcanoes near Crater Lake, Oregon. J. Petrol 31:135–166Google Scholar
  6. Bagby WC, et al (1981) Contrasting evolution of calc-alkalic volcanic and plutonic rocks of Western Chihuahua, Mexico. J Geophys Res 86:10402–10410Google Scholar
  7. Beard JS, Lofgren GE (1989) Effect of water on the composition of partial melts of greenstone and amphibolite. Science 244: 195–197Google Scholar
  8. Beard JS, Lofgren GE (1991) Dehydration melting and water-saturated melting of basaltic and andesitic greenstones and amphibolites at 1, 3 and 6.9 kbar. J Petrol 32:365–402Google Scholar
  9. Bergantz GW (1989) Underplating and partial melting: implications for melt generation and extraction. Science 245:1093–1095Google Scholar
  10. Boily M, et al (1989) Chemical and isotopic evolution of the Coastal Batholith of Southern Peru. J Geophys Res 94:12483–12498Google Scholar
  11. Boynton WV (1984) Cosmochemistry of the rare earth elements: meteorite studies. In: Henderson P (ed) Rare earth element geochemistry. Elsevier, Amsterdam New York, pp 63–114Google Scholar
  12. Burnham CW (1979a) Magmas and hydrothermal fluids. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits. Wiley Interscience, New York, pp 71–136Google Scholar
  13. Burnham CW (1979b) The importance of volatile constituents. In: Yoder HS (ed) The evolution of the igneous rocks-fiftieth anniversary perspectives. Princeton Univ. Press, Princeton, pp 439–482Google Scholar
  14. Carroll MR, Wyllie PJ (1990) The system tonalite-H2O at 15 kbar and the genesis of calc-alkaline magmas. Am Mineral 75: 345–357Google Scholar
  15. Chappell BW, White A (1974) Two contrasting granite types (expanded abstract). Pacific Geol 8:173–174Google Scholar
  16. Chappell BW, et al (1987) The importance of residual source material (restite) in granite petrogenesis. J Petrol 28:1111–1138Google Scholar
  17. Clemens JD, Vielzeuf D (1987) Constraints on melting and magma production in the crust. Earth Planet Sci Lett 86:287–306Google Scholar
  18. Conrad WK, Kay RW (1984) Ultramafic and mafic inclusions from Adak Island: crystallization history, and implications for the nature of primary magmas and crustal evolution in the Aleutian Arc. J Petrol 25:88–125Google Scholar
  19. Crock JG, et al (1986) Separation and preconcentration of the rare-earth elements and yttrium from geological materials by ionexchange and sequential acid elution. Talanta 7:601–606Google Scholar
  20. Czamanske GK, Wones DR (1973) Oxidation during magmatic differentiation, Finnmarka Complex, Oslo area, Norway: part 2, the mafic silicates. J Petrol 14:349–380Google Scholar
  21. DePaolo DJ (1981) A neodymium and strontium isotopic study of the Mesozoic calc-alkaline granitic batholiths of the Sierra Nevada and Peninsular Ranges, California. J Geophys Res 86:10470–10488Google Scholar
  22. Dilles JH (1987) Petrology of the Yerington batholith: evidence for evolution of porphyry copper ore fluids. Econ Geol 82: 1750–1789Google Scholar
  23. Dodge FCW, et al (1982) Compositional variations and abundances of selected elements in granitoid rocks and constituent minerals, Central Sierra Nevada Batholith, California. USGS Prof Pap 1248Google Scholar
  24. Eggins S, Hensen BJ (1987) Evolution of mantle-derived, augitehypersthene granodiorites by crystal-liquid fractionation: Barrington Tops batholith, eastern Australia. Lithos 20:295–310Google Scholar
  25. Eggler DH (1972) Amphibole stability in H2O-undersaturated calcalkaline melts. Earth Planet Sci Lett 15:28–34Google Scholar
  26. Engles JC, et al (1976) Summary of K−Ar, U−Pb, Pb-alpha, and fission track ages of rocks from Washington state prior to 1975 (exclusive of Columbia Plateau basalts). USGS Misc Field Studies Map MF-710Google Scholar
  27. Erickson EH Jr (1977) Petrology and petrogenesis of the Mount Stuart batholith-plutonic equivalent of the high alumina basalt association? Contrib Mineral Petrol 60:183–207Google Scholar
  28. Farmer GL, DePaolo DJ (1983) Origin of Mesozoic and Tertiary granite in the western United States and implications for pre-Mesozoic crustal structure 1: Nd and Sr isotopic studies in the geocline of the northern Great Basin. J Geophys Res 88:3379–3401Google Scholar
  29. Fountain JC, et al (1989) Melt segregation in anatectic granites: a thermo-gravitational model. J Volcanol Geotherm Res 39: 279–296Google Scholar
  30. Fujimaki H, et al (1984) Partition coefficients of Hf, Zr, and REE between phenocrysts and groundmasses. J Geophys Res 89:B662-B672Google Scholar
  31. Green TH, Pearson NJ (1985) Rare earth element partitioning between clinopyroxene and silicate liquid at moderate to high pressure. Contrib Mineral Petrol 91:24–36Google Scholar
  32. Gromet LP, Silver LT (1987) REE variations across the Peninsular Ranges batholith: implications for batholithic petrogenesis and crustal growth in magmatic arcs. J Petrol 28:75–125Google Scholar
  33. Hammarstrom JM, Zen E-An (1986) Aluminum in hornblende: an empirical geobarometer, Am Mineral 71:1297–1313Google Scholar
  34. Harrison TM, Watson EB (1984) The behaviour of apatite during crustal anatexis: equilibrium and kinetic considerations. Geochim Cosmochim Acta 48:1467–1477Google Scholar
  35. Helz RT (1976) Phase relations of basalts in their melting ranges at P H 2 O=5 kbar, part II: melt compositions. J Petrol 17:139–193Google Scholar
  36. Hildreth W, Moorbath S (1988) Crustal contributions to arc magmatism in the Andes of Central Chile. Contrib Mineral Petrol 98:455–489Google Scholar
  37. Hill RI (1988) San Jacinto intrusive complex 1: geology and mineral chemistry, and a model for intermittant rechange of tonalitic magma chambers. J Geophys Res 93:10325–10348Google Scholar
  38. Holloway JR, Burnham CW (1972) Melting relations of basalt with equilibrium water pressure less than total pressure, J Petrol 13:1–29Google Scholar
  39. Huang WL, Wyllie PJ (1986) Phase relationships of gabbro-tonalitegranite-water at 15 kbar with applications to differentiation and anatexis. Am Mineral 71:301–316Google Scholar
  40. Irving AJ, Frey FA (1984) Trace element abundances in megacrysts and their host basalts: constraints on partition coefficients and megacryst genesis. Geochim Cosmochim Acta 48:1201–1221.Google Scholar
  41. Kiline IA, Burnham CW (1972) Partitioning of chloride between a silicate melt and coexisting aqueous phase from 2 to 8 kilobars. Econ Geol 67:231–235Google Scholar
  42. Kistler RW, et al (1986) Isotopic variation in the Tuolumne Intrusive Suite, central Sierra Nevada, California. Contrib Mineral Petrol 94:205–220Google Scholar
  43. Le Bel L, et al (1985) A high-K, mantle derived plutonic suite from ‘Linga’, near Arequipa (Peru). J Petrol 26:124–148Google Scholar
  44. LeMaitre RW (1989) A classification of igneous rocks and glossary of terms. Blackwell Scientific, OxfordGoogle Scholar
  45. Luhr JF, Carmichael ISE (1980) The Colima volcanic complex, Mexico. Contrib Mineral Petrol 71:343–372Google Scholar
  46. 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. Can Inst Min Metall 8:pp 101–148Google Scholar
  47. Mooney WD, Weaver CS (1989) Regional crustal structure and tectonics of the Pacific Coastal states; California, Oregon, and Washington. In: Pakiser LC, Mooney WD (eds) Geophysical framework of the continental United States. GSA Mem 172: pp 129–162Google Scholar
  48. Naney MT (1983) Phase equilibria of rock-forming ferromagnesian silicates in granitic systems. Am J Sci 283:993–1033Google Scholar
  49. Noyes HJ, et al (1983) A tale of two plutons: geochemical evidence bearing on the origin and differentiation of the Red Lake and Eagle Peak plutons, central Sierra Nevada, California. J Geol 91:487–509Google Scholar
  50. Perfit MR, et al (1980) Trace element and isotopic variations in a zoned pluton and associated volcanic rocks, Unalaska Island, Alaska: a model for fractionation in the Aleutian calcalkaline suite. Contrib Mineral Petrol 73:69–87Google Scholar
  51. Pitcher WS (1987) Granites and yet more granites forty years on. Geol Rundsch 76:51–79Google Scholar
  52. Reid JB, et al (1983) Magma mixing in granitic rocks of the Central Sierra Nevada, California. Earth Planet Sci Lett 66:243–261Google Scholar
  53. Richards TA (1971) Plutonic rocks between Hope, B.C., and the 49th Parallel (unpubl). PhD dissertation, Univ British ColumbiaGoogle Scholar
  54. Rushmer T (1991) Partial melting of two amphibolites: contrasting experimental results under fluid absent conditions. Contrib Mineral Petrol 107:41–59Google Scholar
  55. Rutter MJ, Wyllie PJ (1988) Melting of vapour-absent tonalite at 10 kbar to simulate dehydration-melting in the deep crust. Nature 331:159–160Google Scholar
  56. Takahashi E (1986) Genesis of calc-alkali andesite magma in a hydrous mantle-crust boundary: petrology of lherzolite xenoliths from the lchinomegata crater, Oga Peninsula, northeast Japan, part II. J Volcanol Geotherm Res 29:355–395Google Scholar
  57. Tepper JH (1991) Petrology of mafic plutons and their role in granitoid genesis, Chilliwack batholith, North Cascades, Washington (unpubl). PhD dissertation, Univ of WashingtonGoogle Scholar
  58. Ulmer P (1989) The dependence of the Fe2+−Mg cation-partitioning between olivine and basaltic liquid on pressure, temperature, and composition. Contrib Mineral Petrol 101:261–273Google Scholar
  59. Walawender MJ, Smith TE (1980) Geochemical and petrologic evolution of the basic plutons of the Peninsular Ranges batholith, southern California. J Geol 88:233–242Google Scholar
  60. Watson EB, Green TH (1981) Apatite/liquid partition coefficients for the rare earth elements and strontium. Earth Planet Sci Lett 56:405–421Google Scholar
  61. Wolf MB, Wyllie PJ (1989) The formation of tonalitic liquids during the vapor-absent partial melting of amphibolite at 10 kbar. Eos 70:506Google Scholar
  62. Wyllie PJ, et al (1976) Granitic magmas: possible and impossible sources, water contents, and crystallization sequences. Can J Earth Sci 13:1007–1019Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Jeffrey H. Tepper
    • 1
  • Bruce K. Nelson
    • 1
  • George W. Bergantz
    • 1
  • Anthony J. Irving
    • 1
  1. 1.Department of Geological Sciences, AJ-20University of WashingtonSeattleUSA

Personalised recommendations