Skip to main content Accessibility help
Hostname: page-component-684899dbb8-ndjvl Total loading time: 0.567 Render date: 2022-05-23T10:48:30.721Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "useRatesEcommerce": false, "useNewApi": true }

Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon

Published online by Cambridge University Press:  03 November 2011

Timothy H. Druitt
Department of Earth Sciences, University of Liverpool, P.O. Box 149, Liverpool L69 3BX, U.K.
Charles R. Bacon
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, U.S.A.


The 6845 ± 50 BP climactic eruption of Mount Mazama discharged 47 ± 9 km3 of vertically zoned calc-alkaline magma, affording a virtually complete section through the chamber. Evidence for two andesitic parents with different trace-element (particularly Sr) and water contents is preserved in the ejecta. Prior to eruption, a dominant volume of rhyodacite was underlain successively by high-Sr andesite, high-Sr crystal mushes, and low-Sr crystal mushes. Intergranular liquids in the high-Sr magmas were probably richer in water than those in the low-Sr magmas. Thermal continuity throughout the ejecta favours eruption from a single, zoned reservoir. Insight into chamber development is given by preclimactic rhyodacitic lavas and tephra erupted between about 30,000 BP and the climactic eruption. The oldest of these lavas, contaminated derivatives of low-Sr magma, contain crystal-poor magmatic inclusions of low-Sr andesite; the youngest has inclusions of high-Sr andesite and, like rhyodacitic pumice in the climactic ejecta, is hybrid magma containing an admixed high-Sr component. A model for steady-state growth of the chamber is inferred whereby repeated recharge, first by low-Sr then high-Sr andesite (± basalt), builds up a cumulate succession, while derivative liquid fractionates convectively, segregates, and mixes with an incrementally growing silicic volume. The magma chamber at Mount Mazama may provide insight into the evolution of some granitoid plutons.

Research Article
Copyright © Royal Society of Edinburgh 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Andersen, D. J. & Lindsley, D. H. 1988. Internally consistent solution models for Fe–Mg–Mn–Ti oxides: Part I. Fe–Ti oxides. AM MINERAL (in press).Google Scholar
Anderson, A. T. 1980. Significance of hornblende in calc-alkaline andesites and basalts. AM MINERAL 65, 837851.Google Scholar
Bacon, C. R. 1983. Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A. J VOLCANOL GEOTHERM RES 18, 57115.CrossRefGoogle Scholar
Bacon, C. R. 1985. Implications of silicic vent patterns for the presence of large crustal magma chambers. J GEOPHYS RES 90, 1124311252.CrossRefGoogle Scholar
Bacon, C. R. 1986. Magmatic inclusions in silicic and intermediate volcanic rocks. J GEOPHYS RES 91, 60916112.CrossRefGoogle Scholar
Bacon, C. R. 1988. Shoshonite, calcalkaline basalt and andesite, and low-K tholeiite near Crater Lake, Oregon. TRANS AM GEOPHYS UNION 68, 1516.Google Scholar
Bacon, C. R. & Druitt, T. H. 1988. Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon. CONTRIB MINERAL PETROL 98, 224256.CrossRefGoogle Scholar
Bacon, C. R. & Lanphere, M. A. 1983. K–Ar chronology of eruptions at Mount Mazama before the formation of Crater Lake caldera (abs.). TRANS AM GEOPHYS UNION 64, 45879.Google Scholar
Barnes, C. G. 1983. Petrology and upward zonation of the Wooley Creek Batholith, Klamath Mountains, California. J PETROL 24, 495537.CrossRefGoogle Scholar
Bateman, P. C. & Chappell, B. W. 1979. Crystallization, fractionation, and solidification of the Tuolomne intrusive series, Yosemite National Park, California. GEOL SOC AM BULL 90, 465482.2.0.CO;2>CrossRefGoogle Scholar
Blake, S. & Campbell, I. H. 1986. The dynamics of magma mixing during flow in volcanic conduits. CONTRIB MINERAL PETROL 94, 7281.CrossRefGoogle Scholar
Blake, S. & Ivey, G. N. 1986. Magma mixing and the dynamics of withdrawal from stratified reservoirs. J VOLCANOL GEOTHERM RES 27, 153178.CrossRefGoogle Scholar
Bruggman, P. E., Bacon, C. R., Aruscavage, P. J., Lerner, R. W., Schwarz, L. J. & Stewart, K. C. 1987. Chemical analyses of rocks and glass separates from Crater Lake National Park and vicinity, Oregon. US GEOL SURV OPEN-FILE REP 87–57.Google Scholar
Campbell, I. H. & Turner, J. S. 1986. The influence of viscosity on fountains in magma chambers. J PETROL 27, 130.CrossRefGoogle Scholar
Cantagrel, J.-M., Didier, J. & Gourgaud, A. 1984. Magma mixing: origin of intermediate rocks and “enclaves” from volcanism to plutonism. PHYS EARTH PLANET INT 35, 6376.CrossRefGoogle Scholar
Chen, C. F. & Turner, J. S. 1980. Crystallization in a double-diffusive convective system. J GEOPHYS RES 85, 25732593.CrossRefGoogle Scholar
Druitt, T. H. & Bacon, C. R. 1986. Lithic breccia and ignimbrite erupted during the collapse of Crater Lake caldera, Oregon. J VOLCANOL GEOTHERM RES 29, 132.CrossRefGoogle Scholar
Druitt, T. H. & Bacon, C. R. 1988. Petrology of the zoned calcalkaline magma body at Mount Mazama (Crater Lake), Oregon, (subjudice)Google Scholar
Eichelberger, J. C. 1980. Vesiculation of mafic magma during replenishment of silicic magma reservoirs. NATURE 288, 446450.CrossRefGoogle Scholar
Flood, R. H. & Shaw, S. E. 1979. K-rich cumulate diorite at the base of a tilted granodiorite pluton from the New England batholith, Australia. J GEOL 87, 417425.CrossRefGoogle Scholar
Freundt, A. & Tait, S. R. 1987. The entrainment of high-viscosity magma into low–viscosity magma in eruption conduits. BULL VOLCANOL 48, 325339.Google Scholar
Fridrich, C. J. & Mahood, G. A. 1984. Reverse zoning in the resurgent intrusion of the Grizzly Peak Cauldron, Sawatch Range, Colorado. GEOL SOC AM BULL 95, 779787.2.0.CO;2>CrossRefGoogle Scholar
Hildreth, W. 1981. Gradients in silicic magma chambers: implications for lithospheric magmatism. J GEOPHYS RES 86, 1015310192.CrossRefGoogle Scholar
Huebner, J. S. & Sato, M. 1970. The oxygen fugacity-temperature relationships of manganese oxide and nickel oxide buffers. AM MINERAL 55, 934952.Google Scholar
Huppert, H. E., Sparks, R. S. J. & Turner, J. S. 1983. Laboratory investigation of viscous effects in replenished magma chambers. EARTH PLANET SCI LETT 65, 377381.CrossRefGoogle Scholar
Irvine, T. N. 1980. Magmatic infiltration metasomatism, double-diffusive fractional crystallization, and adcumulate growth in the Muskox Intrusion and other layered intrusions. In Hargraves, R. B. (ed.) Physics of magmatic processes, 245306. Princeton: Princeton University Press.Google Scholar
Irvine, T. N. 1982. Terminology for layered intrusions. J PETROL 23, 127162.CrossRefGoogle Scholar
Lidstrom, J. W. Jr., 1971. A new model for the formation of Crater Lake Caldera, Oregon. Ph.D. Thesis, Oregon State University, Corvallis.Google Scholar
Marsh, B. D. 1981. On the crystallinity, probability of occurrence, and rheology of lava and magma. CONTRIB MINERAL PETROL 78, 8598.CrossRefGoogle Scholar
McBirney, A. R. 1968. Compositional variation in the climactic eruption of Mount Mazama. In Dole, H. M. (ed.) Andesite Conference Guidebook. OREGON DEP GEOL MINER IND BULL 62, 5356.Google Scholar
McBirney, A. R., Baker, B. H. & Nilson, R. H. 1985. Liquid fractionation. Part I: Basic principles and experimental simulations. J VOLCANOL GEOTHERM RES 24, 124.CrossRefGoogle Scholar
McCarthy, T. S. & Groves, D. I. 1979. The Blue Tier batholith, northeastern Tasmania. CONTRIB MINERAL PETROL 71, 193209.CrossRefGoogle Scholar
Myers, J. & Eugster, H. P. 1983. The system Fe–Si–O: oxygen buffer calibration to l,500K. CONTRIB MINERAL PETROL 82, 7590.CrossRefGoogle Scholar
Nabelek, P. I., Papike, J. J. & Laul, J. C. 1986. The Notch Peak granitic stock, Utah: Origin of reverse zoning and petrogenesis. J PETROL 27, 10351069.CrossRefGoogle Scholar
Nilson, R. H., McBirney, A. R. & Baker, B. H. 1985. Liquid fractionation. Part II: Fluid dynamics and quantitative implications for magmatic systems. J VOLCANOL GEOTHERM RES 24, 2554.CrossRefGoogle Scholar
Noble, D. C., Drake, J. C. & Whallon, M. K. 1969. Some preliminary observations on compositional variation within the pumice- and scoria-flow deposits of Mount Mazama. In McBirney, A. R. (ed.) Proceedings of the Andesite Conference. OREGON DEP GEOL MINER IND BULL 65, 157164.Google Scholar
Perfit, M. R., Brueckner, H., Lawrence, J. R. & Kay, R. W. 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, 6987.CrossRefGoogle Scholar
Ragland, P. C. & Butler, J. R. 1972. Crystallization of the West Farrington Pluton, north Carolina. J PETROL 13, 381404.CrossRefGoogle Scholar
Reid, J. B. Jr., Evans, O. C. & Fates, D. G. 1983. Magma mixing in granitic rocks of the central Sierra Nevada, California. EARTH PLANET SCI LETT 66, 243261.CrossRefGoogle Scholar
Ritchey, J. L. 1980. Divergent magmas at Crater Lake, Oregon: products of fractional crystallization and vertical zoning in a shallow, water-undersaturated chamber. J VOLCANOL GEOTHERM RES 7, 373386.CrossRefGoogle Scholar
Sakuyama, M. 1984. Magma mixing and magma plumbing systems in island arcs. BULL VOLCANOL 47, 685703.CrossRefGoogle Scholar
Smith, R. L. 1979. Ash-flow magmatism. GEOL SOC AM SPEC PAP 180, 527.Google Scholar
Snoke, A. W., Quick, J. E. & Bowman, H. R. 1981. Bear Mountain igneous complex, Klamath Mountains, California; an ultrabasic to silicic calc-alkaline suite. J PETROL 22, 501552.CrossRefGoogle Scholar
Sparks, R. S. J., Huppert, H. E. & Turner, J. S. 1984. The fluid dynamics of evolving magma chambers. PHILOS TRANS R SOC LONDON 310, 511534.CrossRefGoogle Scholar
Sparks, R. S. J., Huppert, H. E., Kerr, R. C., McKenzie, D. P. & Tait, S. R. 1985. Postcumulus processes in layered intrusions. GEOL MAG 122, 555568.CrossRefGoogle Scholar
Sparks, R. S. J. & Marshall, L. 1986. Thermal and mechanical constraints on mixing between mafic and silicic magmas. J VOLCANOL GEOTHERM RES 29, 99124.CrossRefGoogle Scholar
Spera, F. J., Yuen, D. A., Greer, J. C. & Sewell, G. 1986. Dynamics of magma withdrawal from stratified magma chambers. GEOLOGY 14, 723726.2.0.CO;2>CrossRefGoogle Scholar
Stormer, J. C. 1983. The effects of recalculation on estimates of temperature and oxygen fugacity from analyses of multicomponent iron-titanium oxides. AM MINERAL 68, 586594.Google Scholar
Taubeneck, W. H. 1967. Petrology of the Cornucopia Tonalite Unit, Cornucopia Stock, Wallowa Mountains, northeastern Oregon. GEOL SOC AM SPEC PAP 91.Google Scholar
Tindle, A. G. & Pearce, J. A. 1981. Petrogenetic modelling of in situ fractional crystallization in the zoned Loch Doon pluton, Scotland. CONTRIB MINERAL PETROL 78, 196207.CrossRefGoogle Scholar
Vernon, R. H. 1983. Restite, xenoliths, and microgranitoid enclaves in granites. J PROC R SOC NEW SOUTH WALES 116, 77103.Google Scholar
Wager, L. R., Brown, G. M. & Wadsworth, W. J. 1960. Types of igneous cumulate. J PETROL 1, 7385.CrossRefGoogle Scholar
Wiebe, R. A. & Wild, T. 1983. Fractional crystallisation and magma mixing in the Tigalak layered intrusion, the Nain anorthosite complex, Labrador. CONTRIB MINERAL PETROL 84, 327344.CrossRefGoogle Scholar
Williams, H. 1942. The geology of Crater Lake National Park, Oregon. CARNEGIE INST WASHINGTON PUBL 540.Google Scholar
Cited by

Save article to Kindle

To save this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the or variations. ‘’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon
Available formats

Save article to Dropbox

To save this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about saving content to Dropbox.

Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon
Available formats

Save article to Google Drive

To save this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about saving content to Google Drive.

Compositional zonation and cumulus processes in the Mount Mazama magma chamber, Crater Lake, Oregon
Available formats

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *