Quaternary tephra from the Valles caldera in the volcanic field o the Jemez Mountains of New Mexico identified in western Canada

Authors Organisations
  • John A. Westgate(Author)
    University of Toronto
  • Giday Woldegabriel(Author)
    Los Alamos National Laboratory
  • Henry C. Halls(Author)
    University of Toronto
  • Colin J. Bray(Author)
    University of Toronto
  • René W. Barendregt(Author)
    University of Lethbridge
  • Nick Pearce(Author)
  • Andrei M. Sarna-Wojcicki(Author)
    United States Geological Survey
  • Michael P. Gorton(Author)
    University of Toronto
  • Richard E. Kelley(Author)
    Los Alamos National Laboratory
  • Emily Schultz-Fellenz(Author)
    Los Alamos National Laboratory
Type Article
Original languageEnglish
Pages (from-to)813-828
Number of pages16
JournalQuaternary Research
Volume91
Issue number2
Early online date27 Dec 2018
DOI
Publication statusPublished - 01 Mar 2019
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Abstract

A fine-grained, up to 3-m-thick tephra bed in southwestern Saskatchewan, herein named Duncairn tephra (Dt), is derived from an early Pleistocene eruption in the Jemez Mountains volcanic field of New Mexico, requiring a trajectory of northward tephra dispersal of ~1500 km. An unusually low CaO content in its glass shards denies a source in the closer Yellowstone and Heise volcanic fields, whereas a Pleistocene tephra bed (LSMt) in the La Sal Mountains of Utah has a very similar glass chemistry to that of the Dt, supporting a more southerly source. Comprehensive characterization of these two distal tephra beds along with samples collected near the Valles caldera in New Mexico, including grain size, mineral assemblage, major- and trace-element composition of glass and minerals, paleomagnetism, and fission-track dating, justify this correlation. Two glass populations each exist in the Dt and LSMt. The proximal correlative of Dt1 is the plinian Tsankawi Pumice and co-ignimbritic ash of the first ignimbrite (Qbt1g) of the 1.24 Ma Tshirege Member of the Bandelier Tuff. The correlative of Dt2 and LSMt is the co-ignimbritic ash of Qbt2. Mixing of Dt1 and Dt2 probably occurred during northward transport in a jet stream

Keywords

  • tephra, Valles caldera, Bandelier Tuff, glass, trace elements, fission-track dating, paleomagnetism, Saskatchewan, Utah, New Mexico