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Early high Cascade silicic volcanism : analysis of the McKenzie Canyon and Lower Bridge tuff



Graduation date: 2013Silicic volcanism in the central Oregon Cascade range has decreased in both the size and frequency of eruptions from its initiation at ~40 Ma to present. The reasons for this reduction in silicic volcanism are poorly constrained. Studies of the petrogenesis of these magmas have the potential for addressing this question by providing insight into the processes responsible for producing and erupting silicic magmas. This study focuses on two extensive and well-preserved ash-flow tuffs from within the ~4-8 Ma Deschutes Formation of central Oregon, which formed after the transition from Western Cascade volcanism to the modern High Cascade. Documentation of outcrop extent, outcrop thickness, clast properties, and samples provide the means to estimate a source location, minimum erupted volumes, and to constrain eruptive processes. Major and trace element chemistry of glass and minerals constrain the petrogenesis and chemical evolution of the system.\ud \ud The tuffs selected for this study, the Lower Bridge and McKenzie Canyon, are the first known silicic units originating from the Cascade Arc following the reorganization from Western Cascade to High Cascade Volcanism at ~8 Ma. These eruptions were significant in producing a minimum of ~5 km³ DRE each within a relatively short timeframe. These tuffs are sourced from some vent or edifices related to the Three Sisters Volcanic Complex, and capture an early phase of the volcanic history of that region. The chemical composition of the tuffs indicates that the Lower Bridge erupted predominately rhyolitic magma with dacitic magma occurring only in small quantities in the latest stage of the eruption while McKenzie Canyon Tuff erupted first as a rhyolite and transitioned to a basaltic andesite with co-mingling and incomplete mixing of the two magma types. Major and trace element concentrations in minerals and glass indicate that the basaltic andesite and rhyolite of the McKenzie Canyon Tuff were well convected and stored in separate chambers. Geothermometry of the magmas indicate that the rhyolites are considerably warmer (~850°) than typical arc rhyolites. Trace element compositions indicate that both the Lower Bridge and McKenzie Canyon Tuff experienced mixing between a mantle derived basaltic melt and a rhyolitic partial melt derived from gabbroic crust. Rhyolites of the Lower Bridge Tuff incorporate 30-50% partial melt following 0->60% fractionation of mantle derived melts. The McKenzie Canyon Tuff incorporates 50-100% of a partial melt of a mafic crust with up to 15% post mixing fractionation.\ud \ud The results of this study suggest that production of voluminous silicic magmas within the Cascade Arc crust requires both fractionation of incoming melts from the mantle together with mixing with partial melts of the crust. This provides a potential explanation for the decrease in silicic melt production rates from the Western Cascades to the High Cascades related to declining subduction rate. As convergence along the Cascade margin became more oblique during the Neogene, the consequent slowing rate of mantle melt production will result in a net cooling of the crust, inhibiting the production of rhyolitic partial melts. Without these partial melts to provide the rhyolitic end member to the system, the system will evolve to the mafic melt and fractionation dominated regime that has existed along Cascadia throughout the Quaternary

Topics: Volcanology, High Cascades, Deschutes
Year: 2012
OAI identifier: oai:ir.library.oregonstate.edu:1957/33198
Provided by: ScholarsArchive@OSU

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  6. 3: Si normalized LA-ICP-MS results for pyroxenes.
  7. (2008). 644 1.215 685 1.053 148 Appendix C: Two Pyroxene Thermobarometry Calculations Table 1: Clinopyroxene-Orthopyroxene Pair Results Cpx Opx Cpx Opx Cpx Opx Sample
  8. (1989). A classification of igneous rocks and glossary of terms, doi
  9. (1991). A field guide to depositional processes and facies geometry of Neogene continental volcaniclastic rocks, Deschutes basin, central Oregon,
  10. (1990). A field guide to the geology of Cove Palisades State Park and the Deschutes Basin in central Oregon,
  11. (1983). A field trip guide to the central oregon cascades,
  12. (1957). A geologic map of the Bend Quadrangle, Oregon,: And a reconnaissance geologic map of the central portion of the High Cascade Mountains, State of Oregon,
  13. (2002). Ages of the Steens and Columbia River flood basalts and their relationship to extension-related calc-alkalic volcanism in eastern Oregon, doi
  14. (1987). An experimental study of Nb and Ta partitioning between Ti-rich minerals and silicate liquids at high pressure and temperature, doi
  15. Appendix D: Plagioclase-Liquid Thermobarometry and hydrometry Calculations Table 1: Liquid-Plagioclase Pair Results Liquid Feldspar Liquid Feldspar Liquid Feldspar Sample / doi
  16. (1994). Application of proton-microprobe data to traceelement partitioning in volcanic rocks, doi
  17. (1994). Ash clouds; characteristics of eruption columns,
  18. (2005). Assembling an ignimbrite; compositionally defined eruptive packages in the 1912 doi
  19. (1976). Behavior of trace elements during magmatic processes; a summary of theoretical models and their applications,
  20. (1992). BIGD.FOR; Fortran program to calculate trace-element partition coefficients for natural mafic and intermediate composition magmas, doi
  21. (1989). Cenozoic Active Margin and Shallow Cascades Structure: COCORP Results from Western Oregon, doi
  22. (1997). Complexities of plinian fall deposition at vent; an example from the 1912 Novarupta eruption (Alaska), doi
  23. (1988). Compositional zonation and cumulus processses in the Mount Mazama magma chamber, doi
  24. (2011). Convergent margin magmatism in the central Andes and its near antipodes in western Indonesia: spatiotemporal and geochemical considerations, Dissertation,
  25. (1989). Cretaceous crust section through the proposed Insular-Intermontane suture, North Cascades, doi
  26. (1995). Crystallization and Welding Variations in a Widespread Ignimbrite Sheet - The Rattlesnake Tuff, doi
  27. (1995). Dehydration melting of metabasalt at 8-32 kbar; implications for continental growth and crust-mantle recycling, doi
  28. (1992). Depletion of Nb relative to other highly incompatible elements by melt/rock reaction in the upper mantle.
  29. Detection Limit Standard FO83 (wt%) Overall Mean* (wt%) 1 Std. Dev Accuracy (%) Mean Detection (ppm)
  30. Detection Limit Standard LABR (wt%) Overall Mean* (wt%) 1 Std. Dev Accuarcy (%) Mean Detection (ppm)
  31. (1988). Distribution of Late Cenozoic Volcanic Vents in the Cascade Range: Volcanic Arc Segmentation and Regional Tectonic Considerations, doi
  32. (1976). Distribution of the period four transition elements among olivine, calcic clinopyroxene and mafic silicate liquid; experimental results, doi
  33. (1986). Dynamics of magma withdrawal from stratified magma chambers, doi
  34. (1974). Episodic Volcanism in the Central Oregon Cascade Range, doi
  35. (2011). Eruptive history of South Sister, Oregon Cascades, doi
  36. (2005). Experimental and geochemical evidence for derivation of the El Capitan Granite, California, by partial melting of hydrous gabbroic lower crust, Contributions to Mineralogy and Petrology, doi
  37. (1978). Experimental determination of nickel partition coefficients between liquid, pargasite, and garnet peridotite minerals and concentration limits of behavior according to Henry’s law at high pressure and temperature, doi
  38. (1998). Experimental determination of partition coefficients for rare earth and high-field-strength elements between clinopyroxene, garnet, and basaltic melt at high pressure, Contributions to Mineralogy and Petrology, doi
  39. (2007). Fault locking, block rotation and crustal deformation in the Pacific Northwest, doi
  40. (2003). Genesis of flood basalts and Basin and Range volcanic rocks from Steens Mountain to the Malheur River gorge, Oregon, doi
  41. (2006). Geochemical database for volcanic rocks of the western Cascades,
  42. (2004). Geochronology of ageprogressive volcanism of the Oregon High Lava Plains; implications for the plume interpretation of Yellowstone, doi
  43. (1998). Geologic Map of the Hinkle Butte Quadrangle, Deschutes County
  44. (1988). Geologic map of the McKenzie Bridge Quadrangle, Lane County,
  45. (1996). Geologic Map of the Steelhead Falls Quadrangle, Deschutes and Jefferson Counties,
  46. (1993). Geologic map of upper Eocene to Holocene volcanic and related rocks in the Cascade Range,
  47. (2000). Geologic map of upper Eocene to Holocene volcanic and related rocks of the Cascade Range,
  48. (1991). Geologic Tour of Cove Palisades State Park near Madras,
  49. (1931). Geology and Water Resources of the Middle Deschutes River Basin, doi
  50. (1983). Geology of a part of the Eagle Butte and Gateway quadrangles east of the Deschutes River, Jefferson County,
  51. (1942). Geology of north central Oregon,
  52. (1970). Geology of part of the northern half of the Bend quadrangle, Jefferson and Deschutes counties,
  53. (1969). Geology of the Fly Creek quadrangle and the north half of Round Butte Dam quadrangle,
  54. (1975). Geology of the Green Ridge area,
  55. (1940). Geology of the Madras quadrangle, Oregon State College.
  56. (1984). Geology of the northwest one-quarter of the Prineville Quadrangle,
  57. (1924). Geology of the Pelton Dam site, Oregon; Unpublished report in the files of the Federal Power
  58. (1989). Geology of the southernmost Deschutes basin, Tumalo quadrangle, Deschutes County,
  59. (1986). Geology, petrology, and volcanic history of a portion of the Cascade Range between latitudes 43 degrees -44 degrees N,
  60. (2002). Geometry of the subducting Juan de Fuca Plate; new constraints from
  61. (1981). Gradients in Silicic Magma Chambers: Implications for Lithospheric Magmatism, doi
  62. (1982). Historic eruptions of Tambora (1815), Krakatau (1883), and Agung doi
  63. (2009). Homogenization processes in silicic magma chambers by stirring and mushification (latent heat buffering), doi
  64. (2005). Igneous Thermometers and Barometers Based on Plagioclase + Liquid Equilibria: Tests of Some Existing Models and New Calibrations, doi
  65. (2000). Ignimbrites of the Deschutes Formation: A Record of Crustal Melting and Magma Mixing,
  66. (2003). ILMAT: an excel worksheet for ilmenite–magnetite geothermometry and geobarometry, doi
  67. (1998). Ion microprobe study of plagioclase-basalt partition experiments at natural concentration levels of trace elements, doi
  68. (1975). K-Ar dates for volcanic rocks, central Cascade Range of Oregon,
  69. (1993). Lessons in reducing volcano risk, doi
  70. Liquid Feldspar Liquid Feldspar Sample / doi
  71. (1988). Mg/Mn Partitioning as a Test for Equilibrium Between Coexisting Fe-Ti Oxides,
  72. (1994). Mineral/matrix partition coefficients for orthopyroxene, plagioclase, and olivine in basaltic to andesitic systems; a combined analytical and experimental study, doi
  73. (2000). Minimum volume of a tephra fallout deposit estimated from a single isopach, doi
  74. (1999). Modelling the global carbon cycle for the past and future evolution of the earth system, doi
  75. (1985). New (and final!) models for the Timagnetite/ilmenite geothermometer and oxygen barometer,
  76. (1961). of Geology and Mineral Industries.
  77. (1983). Origin of the rhyolitic rocks of the Taupo volcanic zone, doi
  78. (1983). Overview of the geology of the central Oregon Cascade Range, Special Paper - Oregon, doi
  79. (1991). Partial melt distributions from inversion of rare earth element concentrations, doi
  80. (1970). Partition coefficients of rare-earth elements between igneous matrix material and rock-forming mineral phenocrysts; II, doi
  81. (1983). Partition coefficients of trace elements; application to volcanic rocks of St. doi
  82. (2000). Physical Properties of Magma, doi
  83. (1964). Potassium-argon dates and the Tertiary floras of North America, doi
  84. (1905). Preliminary report on the geology and water resources of central Oregon, Gov’t print.
  85. (1997). Primitive Magmas at Five Cascade Volcanic Fields; Melts from Hot, Heterogeneous Sub-Arc Mantle,
  86. (1993). Proton microprobe determined trace element partition coefficients between pargasite, augite and silicate or carbonatitic melts,
  87. (2007). Quaternary magmatism in the Cascades; geologic perspectives,
  88. (1968). Reconnaissance Geologic Map of the Madras Quadrangle, Jefferson and Wasco Counties,
  89. (1987). Record of early High Cascade volcanism at Cove Palisades, Oregon: Deschutes Formation volcanic and sedimentary rocks, doi
  90. (1984). Revised stratigraphy of the Deschutes basin, Oregon: implications for the Neogene development of the central Oregon,
  91. (2012). Rhyolitic magmatism of the High Lava Plains and adjacent Northwest Basin and Range, Oregon: implications for the evolution of continental crust,
  92. (2010). Rupture area and displacement of past Cascadia great earthquakes from coastal coseismic subsidence, doi
  93. (2009). Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. doi
  94. (2004). State of the Cascade Arc: stratocone persistence, mafic lava shields, and pyroclastic volcanism 118 associated with intra-arc rift propagation,
  95. (1987). Stratigraphic, sedimentologic, and petrologic record of late Miocene subsidence of the central Oregon High Cascades, doi
  96. (1988). Stratigraphy of the Neogene Volcanic Rocks Along the Lower Metolius River,
  97. (1986). Stratigraphy, sedimentology and petrology of neogene rocks in the Deschutes Basin, Central Oregon: a record of continental-margin volcanism and its influence on fluvial sedimentation in an arc-adjacent basin, Doctorate,
  98. (2005). Subduction of the Nazca Ridge and the Inca Plateau: Insights into the formation of ore deposits in Peru, doi
  99. (2008). Table 1 Continued: Magnetite-Ilmenite Pair Results Magnetite Ilmenite Magnetite Ilmenite Magnetite Ilmenite Magnetite Ilmenite Sample # doi
  100. (2008). Tectonic controls on the nature of large silicic calderas in volcanic arcs, doi
  101. (1987). Temporal variations in plate convergence and eruption rates in the western Cascades, doi
  102. (1953). The ancient volcanoes of Oregon.
  103. (1974). The behavior of some trace elements during solidification of the Skaergaard layered series, doi
  104. (1980). The Colima volcanic complex, Mexico; I, Post-caldera andesites from Volcan Colima, Contributions to Mineralogy and Petrology, doi
  105. (1938). The Deschutes flora of eastern
  106. (1985). The Deschutes Formation–High Cascade transition in the Whitewater River area, Jefferson County,
  107. (1983). The effects of recalculation on estimates of temperature and oxygen fugacity from analyses of multicomponent iron-titanium oxides,
  108. (1988). The Generation of Granitic Magmas by Intrusion of Basalt into Continental Crust, doi
  109. (1993). The generation of uranium series disequilibria by partial melting of spinel peridotite; constraints from partitioning studies, doi
  110. (2011). The Geochemical Evolution of the Aucanquilcha Volcanic Cluster: Prolonged Magmatism and its Crustal Consequences, Dissertation,
  111. (1982). The geology and stratigraphy of the Tertiary volcanic and volcaniclastic rocks, with special emphasis on the Deschutes Formation, from Lake Simtustus to Madras in central
  112. (1993). The Prineville Basalt, north-central Oregon,
  113. (1984). The stratigraphy, geochemistry, and mineralogy of two ashflow tuffs in the Deschutes Formation,
  114. (1982). The Volcanic Explosivity Index (vei) - an Estimate of Explosive Magnitude for Historical Volcanism, doi
  115. (1986). Thermal and mechanical constraints on mixing between mafic and silicic magmas, doi
  116. (2008). Thermodynamics of rhombohedral oxide solid solutions and a revision of the Fe-Ti two-oxide geothermometer and oxygen-barometer, doi
  117. (2008). Thermometers and Barometers for Volcanic Systems, doi
  118. (2008). Three-dimensional seismic velocity structure of the Northwestern United States, doi
  119. (1987). Trace element distribution coefficients in alkaline series, doi
  120. (1988). Trace element evolution in the Phlegrean Fields (central Italy); fractional crystallization and selective enrichment, Contributions to Mineralogy and Petrology, doi
  121. (2003). Trehu
  122. (2010). Volatile contents of mafic magmas from cinder cones in the Central Oregon High Cascades: Implications for magma formation and mantle conditions in a hot arc, doi
  123. (1990). Volcanic and Tectonic Evolution of the Cascade Volcanic Arc, Central Oregon, doi
  124. (1990). Volcanic Hazards in the Pacific-Northwest,
  125. (1990). Volcanic History and Tectonic Development of the Central High Cascade Range, Oregon, doi
  126. (1985). Volcanic stratigraphy of the Deschutes Formation, Green Ridge to Fly Creek, north-central
  127. (2005). Voluminous granitic magmas from common basaltic sources, Contributions to Mineralogy and Petrology, doi
  128. (1985). X'Usp & X'Ilm from: Temp (°C) ΔNNO
  129. (1985). X'Usp & X'Ilm from: Temp (°C) ΔNNO Temp (°C) ΔNNO Temp (°C) ΔNNO
  130. (1978). XLFRAC; a program for the interactive testing of magmatic differentiation models, doi
  131. (1983). ΔNNO 146 Stormer

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