Contributions to Mineralogy and Petrology

, Volume 152, Issue 6, pp 649–665 | Cite as

U–Pb zircon geochronology of silicic tuffs from the Timber Mountain/Oasis Valley caldera complex, Nevada: rapid generation of large volume magmas by shallow-level remelting

  • Ilya N. BindemanEmail author
  • Axel K. Schmitt
  • John W. Valley
Original Paper


Large volumes of silicic magma were produced on a very short timescale in the nested caldera complex of the SW Nevada volcanic field (SWNVF). Voluminous ash flows erupted in two paired events: Topopah Spring (TS, >1,200 km3, 12.8 Ma)–Tiva Canyon (TC, 1,000 km3, 12.7 Ma) and Rainier Mesa (RM, 1,200 km3, 11.6 Ma)–Ammonia Tanks (AT, 900 km3, 11.45 Ma; all cited ages are previously published 40Ar/39Ar sanidine ages). Within each pair, eruptions are separated by only 0.1–0.15 My and produced tuffs with contrasting isotopic values. These events represent nearly complete evacuation of sheet-like magma chambers formed in the extensional Basin and Range environment. We present ion microprobe ages from zircons in the zoned ash-flow sheets of TS, TC, RM, and AT in conjunction with δ18O values of zircons and other phenocrysts, which differ dramatically among subsequently erupted units. Bulk zircons in the low-δ18O AT cycle were earlier determined to exhibit ∼1.5‰ core-to-rim oxygen isotope zoning; and high-spatial resolution zircon analyses by ion microprobe reveal the presence of older grains that are zoned by 0.5–2.5‰. The following U–Pb isochron ages were calculated after correcting for the initial U–Pb disequilibria: AT (zircon rims: 11.7 ± 0.2 Ma; cores: 12.0 ± 0.1 Ma); pre-AT rhyolite lava: (12.0 ± 0.3 Ma); RM: 12.4 ± 0.3); TC: (13.2 ± 0.15 Ma); TS: (13.5 ± 0.2). Average zircon crystallization ages calculated from weighted regression or cumulative averaging are older than the Ar–Ar stratigraphy, but preserve the comparably short time gaps within each of two major eruption cycles (TS/TC, RM/AT). Notably, every sample yields average zircon ages that are 0.70–0.35 Ma older than the respective Ar–Ar eruption ages. The Th/U ratio of SWNVF zircons are 0.4–4.7, higher than typically found in igneous zircons, which correlates with elevated Th/U of the whole rocks (5–16). High Th/U could be explained if uranium was preferentially removed by hydrothermal solutions or is retained in the protolith during partial melting. For low-δ18O AT-cycle magmas, rim ages from unpolished zircons overlap within analytical uncertainties with the 40Ar/39Ar eruption age compared to core ages that are on average ∼0.2–0.3 My older than even the age of the preceding caldera forming eruption of RM tuff. This age difference, the core-to-rim oxygen isotope zoning in AT zircons, and disequilibrium quartz–zircon and melt-zircon isotopic fractionations suggest that AT magma recycled older zircons derived from the RM and older eruptive cycles. These results suggest that the low-δ18O AT magmas were generated by melting a hydrothermally-altered protolith from the same nested complex that erupted high-δ18O magmas of the RM cycle only 0.15 My prior to the eruption of the AT, the largest volume low-δ18O magma presently known.


Paintbrush tuff Timber Mountain tuff Oxygen isotopes Geochronology Isotope zoning Zircon Yucca Mountain 



This research was supported by the University of Oregon, US Department of Energy under grant FGO2-93ER14389, DOE/NV/14389-2001-1). We thank IF-EAR program of the NSF for support of the ion microprobe facilities at UCLA and UW-Madison. Tom Vogel and Jake Lowenstern are thanked for thoughtful reviews.

Supplementary material


  1. Annen C, Sparks RSJ (2002) Effects of repetitive emplacement of basaltic intrusions on thermal evolution and melt generation in the crust. Earth Planet Sci Lett 203:937–955CrossRefGoogle Scholar
  2. Bachmann O, Bergantz GW (2003) Rejuvenation of the Fish Canyon magma body: a window into the evolution of large-volume silicic magma systems. Geology 31:789–792CrossRefGoogle Scholar
  3. Bachmann O, Bergantz GW (2004) On the origin of crystal-poor rhyolites: extracted from Batholithic crystal mushes. J Petrol 45:1565–1582CrossRefGoogle Scholar
  4. Bachmann O, Dungan MA , Lipman PW (2000) Voluminous lava-like precursor to a major ash-flow tuff: low-column pyroclastic eruption of the Pagosa Peak Dacite San Juan volcanic field Colorado. J Volcanol Geotherm Res 98:153–171CrossRefGoogle Scholar
  5. Bacon CR (1983) Eruptive history of mount Mazama and Crater Lake caldera Cascade Range USA. J Volcanol Geotherm Res 18(1–4):57–115CrossRefGoogle Scholar
  6. Bacon CR, Lowenstern JB (2005) Late Pleistocene granodiorite source for recycled zircon and phenocrysts in rhyodacite lava at Crater Lake Oregon. Earth Planet Sci Lett 233:277–293CrossRefGoogle Scholar
  7. Beard JS, Ragland PC, Crawford ML (2005) Reactive bulk assimilation: a model for crust-mantle mixing in silicic magmas. Geology 33:681–684CrossRefGoogle Scholar
  8. Bindeman IN (2003) Crystal sizes in evolving silicic magma chambers. Geology 31:367–370CrossRefGoogle Scholar
  9. Bindeman IN, Valley JW (2001) Low-δ18O rhyolites from Yellowstone: magmatic evolution based on analyses of zircons and individual phenocrysts. J Petrol 42:1491–1517CrossRefGoogle Scholar
  10. Bindeman IN, Valley JW (2002) Oxygen isotope study of Long-Valley magma system: isotope thermometry and role of convection. Contrib Mineral Petrol 144:185–205Google Scholar
  11. Bindeman IN, Valley JW (2003) Rapid generation of both high- and low-delta O-18 large-volume silicic magmas at the Timber Mountain/Oasis Valley caldera complex Nevada. Geol Soc Am Bull 115:581–595CrossRefGoogle Scholar
  12. Bindeman IN, Valley JW, Wooden JL, Persing HM (2001) Post-caldera volcanism: in situ measurement of U–Pb age and oxygen isotope ratio in Pleistocene zircons from Yellowstone caldera. Earth Planet Sci Lett 189:197–206CrossRefGoogle Scholar
  13. Bindeman IN, Sigmarsson O, Eiler J (2006) Time constraints on the origin of large volume basalts derived from O-isotope and trace element mineral zoning and U-series disequilibria in the Laki and Grimsvotn volcanic system. Earth Planet Sci Lett 245(1–2):245–259CrossRefGoogle Scholar
  14. Black LP, Kamo SL, Allen CM, Aleinikoff JN, Davis DW, Korsch RJ, Foudoulis C (2004) TEMORA 1: a new zircon standard for Phanerozoic U–Pb geochronology. Chem Geol 200:155–170CrossRefGoogle Scholar
  15. Blundy J, Wood B (2003) Mineral-melt partitioning of uranium thorium and their daughters. In: Bourdon B, Henderson GM, Lundstrom CC, Turner SP (eds) Uranium-series geochemistry. Rev Mineral Geochem 52: 59–123Google Scholar
  16. Boroughs S, Wolff J, Bonnichsen B, Godchaux M, Larson P (2005) Large-volume, low-delta O-18 rhyolites of the central Snake River Plain, Idaho, USA. Geology 33:821–824CrossRefGoogle Scholar
  17. Broxton DE, Warren RG, Byers FM Jr, Scott RB (1989) Chemical and mineralogic trends within the Timber Mountain-Oasis Valley caldera complex NV: evidence for multiple cycles of chemical evolution in a long-lived silicic magma system. J Geophys Res 94:5961–5985Google Scholar
  18. Byers FM Jr, Carr WJ, Christiansen RL, Lipman PW, Orkild PP, Quinlivan WD (1976a) Volcanic suites and related cauldrons of Timber Mountain-Oasis valley caldera complex Southern Nevada. US Geological Survey Professional Paper 919:71Google Scholar
  19. Byers FM Jr, Carr WJ, Orkild PP, Quinlivan WD, Sargent KA (1976b) Geologic map of the Timber Mountain caldera area Nye county Nevada US Geological Survey Miscellaneous Investigations Series: Map I-891 1 sheetGoogle Scholar
  20. Byers FM Jr, Carr WJ, Orkild PP (1989) Volcanic centers of south-western Nevada: evolution of understanding (1960–1988). J Geophys Res 94:5908–5924Google Scholar
  21. Cambray FW, Vogel TA, Mills JG Jr (1995) Origin of compositional heterogeneities in tuffs of the Timber Mountain Group: the relationship between magma batches and magma transfer and emplacement in an extensional environment. J Geophys Res 100(B8):15793–15805CrossRefGoogle Scholar
  22. Compston W, Williams IS, Meyer C (1984) U–Pb geochronology of zircons from lunar breccia 73217 using a sensitive high mass-resolution ion microprobe. J Geophys Res 89:B525–B534Google Scholar
  23. Costa F, Chakraborty S, Dohmen R (2003) Diffusion coupling between trace and major elements and a model for calculation of magma residence times using plagioclase. Geochim Cosmochim Acta 67:2189–2200CrossRefGoogle Scholar
  24. Charlier BLA, Peate PW, Wilson CJN, Lowenstern JB, Storey M, Brown SJA (2003) Crystallisation ages in coeval silicic magma bodies: 238U–230Th disequilibrium evidence from the Rotoiti and Earthquake Flat eruption deposits, Taupo Volcanic Zone, New Zealand. Earth Planet Sci Lett 206:441–457CrossRefGoogle Scholar
  25. Charlier BLA, Wilson CJN, Lowenstern JB, Blake S, Van Calsteren PW, Davidson JP (2005) Magma generation at a large hyperactive silicic volcano (Taupo New Zealand) revealed by U–Th and U–Pb systematics in zircons. J Petrol 46(1):3–32CrossRefGoogle Scholar
  26. Christiansen RL, Lipman PW, Carr WJ, Byers FM Jr, Orkild PP, Sargent KA (1977) Timber Mountain-Oasis Valley caldera complex of southern Nevada. Geol Soc Am Bull 88:943–959CrossRefGoogle Scholar
  27. Crank J (1975) The mathematics of diffusion 2nd edn Oxford University PressGoogle Scholar
  28. Davies GR, Halliday AN (1998) Development of the Long Valley rhyolitic magma system: Sr and Nd isotope evidence from glasses and individual phenocrysts. Geochim Cosmochim Acta 62:3561–3574CrossRefGoogle Scholar
  29. Dufek J, Bergantz GW (2005) Lower crustal magma genesis and preservation: a stochastic framework for the evaluation of basalt–crust interaction. J Petrol 46:2167–2195CrossRefGoogle Scholar
  30. Eaton GP (1984) The Miocene Great Basin of western North America as an extending back-arc region. In: Carlson RL and Kobayashi K (eds) Geodynamics of back-arc regions. Tectonophys 102:275–295Google Scholar
  31. Farmer GL, Broxton DE, Warren RG, Pickthorn W (1991) Nd Sr and O isotopic variations in metaluminous ash-flow tuffs and related volcanic rocks at the Timber Mountain/Oasis Valley Caldera Complex SW Nevada: implications for the origin and evolution of large-volume silicic magma bodies. Contrib Mineral Petrol 109:53–68CrossRefGoogle Scholar
  32. Flood TP, Vogel TA, Schuraytz BC (1989) Chemical evolution of a magmatic system: the Paintbrush Tuff SW Nevada volcanic field. J Geophys Res 94:5943–5960Google Scholar
  33. Friedman I, Lipman PW, Obradovich JD, Gleason JD, Christiansen RL (1974) Meteoric water in magmas. Science 184:1069–1072CrossRefGoogle Scholar
  34. Ghiorso MS, Sack RO (1991) Fe–Ti oxide geothermometry-thermodynamic formulation and the estimation of intensive variables in silicic magmas. Contrib Mineral Petrol 108:485–510CrossRefGoogle Scholar
  35. Grant NK, Chalokwu CI (1992) Petrology of the Partridge River Intrusion Duluth Complex Minnesota; II Geochemistry and strontium isotope systematics in Drill Core DDH-221. J Petrol 33:1007–1038Google Scholar
  36. Hildreth W, Christiansen RL, O’Neil JR (1984) Catastrophic isotopic modification of rhyolitic magma at times of caldera subsidence, Yellowstone Plateau Volcanic Field. J Geophys Res 89:8339–8369Google Scholar
  37. Hildreth W, Halliday AN, Christiansen RL (1991) Isotopic and chemical evidence concerning the genesis and contamination of basaltic and rhyolitic magmas beneath the Yellowstone Plateau Volcanic Field. J Petrol 32:63–138Google Scholar
  38. Hoskin PWO, Schaltegger U (2003) The composition of zircon and igneous and metamorphic petrogenesis In: Hanchar JM, Hoskin PWO (eds) Zircon. Rev Mineral Geochem 53:27–62Google Scholar
  39. Huysken KT, Vogel TA, Layer PW (1994) Incremental growth of a large-volume chemically zoned magma body—a study of the tephra sequence beneath the Rainier Mesa ash-flow sheet of the Timber Mountain Tuff. Bull Volcanol 56:377–385Google Scholar
  40. Huysken KT, Vogel TA, Layer PW (2001) Tephra sequences as indicators of magma evolution: Ar-40/Ar-39 ages and geochemistry of tephra sequences in the southwest Nevada volcanic field. J Volcanol Geotherm Res 106:85–110CrossRefGoogle Scholar
  41. John BE, Foster DA, Murphy JM, Cheadle MJ, Baines AG, Mark Fanning C, Copeland P (2004) Determining the cooling history of in situ lower oceanic crust—Atlantis Bank, SW Indian Ridge. Earth Planet Sci Lett 222:145–160CrossRefGoogle Scholar
  42. Lipman PW (1971) Iron–titanium oxide phenocrysts in compositionally zoned ash-flow sheets from southern Nevada. J Geology 79:438–456CrossRefGoogle Scholar
  43. Lipman PW (1984) The roots of ash-flow calderas in the western North America: windows into the tops of granitic batholiths. J Geophys Res 89:8801–8841Google Scholar
  44. Lipman PW (1997) Subsidence of ash-flow calderas: relation to caldera size and magma-chamber geometry. Bull Volcanol 59:198–218CrossRefGoogle Scholar
  45. Lipman PW, Friedman I (1975) Interaction of meteoric water with magmas: an oxygen isotope study of ash-flow sheets from southern Nevada. Geol Soc Am Bull 86:695–702CrossRefGoogle Scholar
  46. Lipman PW, Christiansen RL, O’Connor JT (1966) A compositionally-zoned ash-flow sheet in southern Nevada. US Geological Survey Professional Paper 524-F:1–47Google Scholar
  47. Lipman PW, Protska HJ, Christiansen RL (1972) Cenozoic volcanism and plate tectonic evolution of the western United States; I Early and middle Cenozoic. R Soc Lond Phil Trans A 271:217–248Google Scholar
  48. Lowenstern JB, Persing HM, Wooden JL, Lanphere M, Donnelly-Nolan J, Grove TL (2000) U–Th dating of single zircons from young granitoid xenoliths: new tools for understanding volcanic processes. Earth Planet Sci Lett 183:291–302CrossRefGoogle Scholar
  49. Mahon K (1996) The New ‘York’ regression: application of an improved statistical method to geochemistry. Int Geol Rev 38:293–303CrossRefGoogle Scholar
  50. McLelland JM, Bickford ME, Hill BM, Clechenko CC, Valley JW, Hamilton MA (2004) Direct dating of Adirondack massif anorthosite by U–Pb SHRIMP analysis of igneous zircon: implications for AMCG complexes. Geol Soc Am Bull 116:1299–1317CrossRefGoogle Scholar
  51. Miller JS, Wooden JL (2004) Residence Resorption and Recycling of Zircons in Devils Kitchen Rhyolite Coso Volcanic Field, California. J Petrol 45:2155–2170CrossRefGoogle Scholar
  52. Miller CF, McDowell SM, Mapes RW (2003) Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology 31(6):529–532CrossRefGoogle Scholar
  53. Mills JG Jr, Saltoun BW, Vogel TA (1997) Magma batches in the Timber Mountain magmatic system SW Nevada volcanic field Nevada, USA. J Volcanol Geotherm Res 78:185–208CrossRefGoogle Scholar
  54. Paces JB, Miller JD (1993) Precise U–Pb ages of Duluth Complex and related mafic intrusions northeastern Minnesota; geochronological insights to physical petrogenetic paleomagnetic and tectonomagnetic processes associated with the 11 Ga midcontinent rift system. J Geophys Res 98:13997–14013CrossRefGoogle Scholar
  55. Page Z, DeAngelis M, Fu B, Kita N, Lancaster PJ, Valley JW (2006) Slow oxygen diffusion in zircon. Goldschmidt Abstract (in press)Google Scholar
  56. Peck WH, Valley JW, Graham CM (2003) Slow oxygen diffusion rates in igneous zircons from metamorphic rocks. Am Mineral 88:1003–1014Google Scholar
  57. Poldervaart A (1956) Zircon in rocks: 2. Igneous rocks. Am J Sci 254:521–554CrossRefGoogle Scholar
  58. Reid MR, Coath CD (2000) In situ U–Pb ages of zircons from the Bishop Tuff: no evidence for long crystal residence times. Geology 28:443–446CrossRefGoogle Scholar
  59. Reid MR, Coath CD, Harrison MT, McKeegan KD (1997) Prolonged residence times for the youngest rhyolites associated with Long Valley caldera: 230Th–238U ion microprobe dating of young zircons. Earth Planet Sci Lett 150:27–39CrossRefGoogle Scholar
  60. Sawyer DA, Fleck RJ, Lanphere MA, Warren RG, Broxton DE, Hudson MR (1994) Episodic caldera volcanism in the Miocene SW Nevada volcanic field: related stratigraphic framework 40Ar/39Ar geochronology and implications for magmatism and extension. Geol Soc Am Bull 106:1304–1318CrossRefGoogle Scholar
  61. Schärer U (1984) The effect of initial 230Th disequilibrium on young U–Pb ages: the Makalu case Himalaya. Earth Planet Sci Lett 67:191–204CrossRefGoogle Scholar
  62. Schmitt AK, Grove M, Harrison TM, Lovera O, Hulen JB, Walters M (2003a) The Geysers-Cobb mountain magma system California (Part 1): U–Pb zircon ages of volcanic rocks conditions of zircon crystallization and magma residence times. Geochim Cosmochim Acta 67:3423–3442CrossRefGoogle Scholar
  63. Schmitt AK, Grove M, Harrison TM, Lovera O, Hulen JB, Walters M (2003b) The Geysers-Cobb mountain magma system California (Part 2): timescales of pluton emplacement and implications for its thermal history. Geochim Cosmochim Acta 67:3443–3458CrossRefGoogle Scholar
  64. Schuraytz BC, Vogel TA, Younker LW (1989) The Topopah Spring Tuff: evidence for dynamic withdrawal from a layered magma body. J Geophys Res 94:5925–5942Google Scholar
  65. Schwartz JJ, John BE, Cheadle MJ, Miranda EA, Grimes GB, Wooden JL, Dick HJB (2005) Dating the growth of oceanic crust at a slow-spreading Ridge. Science 310:654–657CrossRefGoogle Scholar
  66. Simon JI, Reid MR (2005) The pace of rhyolite differentiation and storage in an ‘archetypical’ silicic magma system Long Valley. Earth Planet Sci Lett 235:123–140CrossRefGoogle Scholar
  67. Sturchio NC, Binz CM, Lewis CH III (1987) Thorium–uranium disequilibrium in a geothermal discharge zone at Yellowstone. Geochim Cosmochim Acta 51:2025–2034CrossRefGoogle Scholar
  68. Tefend KS (2005) Independently generated magma batches in the compositionally zoned ash-flow sheets from the southwest Nevada volcanic field. Ph.D. dissertation, Michigan State University, East LansingGoogle Scholar
  69. Tefend KS, Vogel TA, Flood TP, Ehrlich R (2006) Identifying relationships among Silicic magma batches by polytopic vector analysis: a study of the Topopah Spring and Pah Canyon ash-flow sheets of the southwest Nevada volcanic field. J Volcanol Geotherm Res (in press)Google Scholar
  70. Tepley FJ, Davidson JP (2003) Mineral-scale Sr-isotope constraints on magma evolution and chamber dynamics in the Rum layered intrusion, Scotland. Contrib Mineral Petrol 145:628–641CrossRefGoogle Scholar
  71. Tepley FJ, Davidson JP, Clynne MA (1999) Magmatic interactions as recorded in plagioclase phenocrysts of Chaos Crags, Lassen Volcanic Center, California. J Petrol 40:787–806CrossRefGoogle Scholar
  72. Valley JW (2003) Oxygen isotopes in zircon. Rev Mineral Geochem 53: 343–385CrossRefGoogle Scholar
  73. Valley JW, Bindeman IN, Peck WH (2003) Empirical calibration of oxygen isotope fractionations in zircon. Geochim Cosmochim Acta 67:3257–3266CrossRefGoogle Scholar
  74. Valley JW, Lackey JS, Cavosie AJ, Clechenko CC, Spicuzza MJ, Basei MAS, Bindeman IN, Ferreira VP, Sial AN, King EM, Peck WH, Sinha AK, Wei CS (2005) 4.4 billion years of crustal maturation: oxygen isotopes in magmatic zircon. Contrib Mineral Petrol 150:561–580CrossRefGoogle Scholar
  75. Vazquez JA, Reid MR (2002) Time scales of magma storage and differentiation of voluminous high-silica rhyolites at Yellowstone caldera, Wyoming. Contrib Mineral Petrol 144:274–285Google Scholar
  76. Vogel TA, Aines R (1996) Melt inclusions from chemically zoned ash-flow sheets from the Southwest Nevada volcanic field. J Geophys Res 101:5591–5610CrossRefGoogle Scholar
  77. Vogel TA, Cambray FW, Constenius KN (2001) Origin and emplacement of igneous rocks in the central Wasatch Mountains, Utah. Rocky Mt Geol 36:119–162CrossRefGoogle Scholar
  78. Warren RG, Byers FM Jr, Broxton DE, Freeman SH, Hagan RC (1989) Phenocrysts abundances and glass and phenocrysts compositions as indicator of magmatic environments of large volume ash-flow sheets in southwestern Nevada. J Geophys Res 94:5987–6020Google Scholar
  79. Warren RG, Sawyer DA, Byers FM Jr, Cole GL (2000) A petrographic/geochemical database and stratigraphic framework for the southern Nevada volcanic field. Los Alamos Report
  80. Watson EB (1996) Dissolution, growth and survival of zircons during crustal fusion: kinetic principles, geological models and implications for isotopic inheritance. Trans R Soc Edinb Earth Sci 87:43–56Google Scholar
  81. Watson EB, Harrison TM (1983) Zircon saturation revisited: temperature and compositional effects in a variety of crustal magma types. Earth Planet Sci Lett 64:295–304CrossRefGoogle Scholar
  82. Watson EB, Cherniak DJ (1997) Oxygen diffusion in zircon. Earth Planet Sci Lett 148:527–544CrossRefGoogle Scholar
  83. Wendt I, Carl C (1985) U/Pb dating of discordant 01 Ma old secondary U minerals. Earth Planet Sci Lett 73:278–284CrossRefGoogle Scholar
  84. Wolff JA, Ramos FC (2003) Pb isotope variations among Bandelier Tufffeldspars: no evidence for a long-lived silicic magma chamber. Geology 31:533–536CrossRefGoogle Scholar
  85. Wiedenbeck M, Alle P, Corfu F, Griffin WL, Meier M, Oberli F, Von Quadt A, Roddick JC, Spiegel W (1995) Three natural zircon standards for U–Th–Pb Lu–Hf trace element and REE analyses. Geostandards Newslett 91:1–23Google Scholar
  86. Wiedenbeck M, Hanchar JM, Peck WH, Sylvester P, Valley J, Whitehouse M, Kronz A, Morishita Y, Nasdala L, Fiebig J, Franchi I, Girard JP, Greenwood RC, Hinton R, Kita N, Mason PRD, Norman M, Ogasawara M, Piccoli R, Rhede D, Satoh H, Schulz-Dobrick B, Skar O, Spicuzza MJ, Terada K, Tindle A, Togashi S, Vennemann T, Xie Q, Zheng YF (2004) Further characterisation of the 91500 zircon crystal. Geostand Geoanal Res 28(1):9–39Google Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Ilya N. Bindeman
    • 1
    Email author
  • Axel K. Schmitt
    • 2
  • John W. Valley
    • 3
  1. 1.Department of Geological SciencesUniversity of OregonEugeneUSA
  2. 2.Department of Earth and Space SciencesUCLALos AngelesUSA
  3. 3.Department of Geology and GeophysicsUniversity of WisconsinMadisonUSA

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