Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for the low-δ18O magmatism of the Snake River Plain–Yellowstone hotspot and other low-δ18O large igneous provinces

Tyler B. Blum, Kouki Kitajima, Daisuke Nakashima, Ariel Strickland, Michael J. Spicuzza, John W. Valley

研究成果: Article査読

10 被引用数 (Scopus)

抄録

The Snake River Plain–Yellowstone (SRP-Y) hotspot track represents the largest known low-δ18O igneous province; however, debate persists regarding the timing and distribution of meteoric hydrothermal alteration and subsequent melting/assimilation relative to hotspot magmatism. To further constrain alteration relations for SRP-Y low-δ18O magmatism, we present in situ δ18O and U–Pb analyses of zircon, and laser fluorination δ18O analyses of phenocrysts, from the Lake Owyhee volcanic field (LOVF) of east-central Oregon. U–Pb data place LOVF magmatism between 16.3 and 15.4 Ma, and contain no evidence for xenocrystic zircon. LOVF δ18O(Zrc) values demonstrate (1) both low-δ18O and high-δ18O caldera-forming and pre-/post-caldera magmas, (2) relative increases in δ18O between low-δ18O caldera-forming and post-caldera units, and (3) low-δ18O magmatism associated with extension of the Oregon-Idaho Graben. The new data, along with new compilations of (1) in situ zircon δ18O data for the SRP-Y, and (2) regional δ18O(WR) and δ18O(magma) patterns, further constrain the thermal and structural associations for hydrothermal alteration in the SRP-Y. Models for low-δ18O magmatism must be compatible with (1) δ18O(magma) trends within individual SRP-Y eruptive centers, (2) along axis trends in δ18O(magma), and (3) the high concentration of low-δ18O magmas relative to the surrounding regions. When considered with the structural and thermal evolution of the SRP-Y, these constraints support low-δ18O magma genesis originating from syn-hotspot meteoric hydrothermal alteration, driven by hotspot-derived thermal fluxes superimposed on extensional tectonics. This model is not restricted to continental hotspot settings and may apply to several other low-δ18O igneous provinces with similar thermal and structural associations.

本文言語English
論文番号92
ジャーナルContributions to Mineralogy and Petrology
171
11
DOI
出版ステータスPublished - 2016 11 1

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

フィンガープリント 「Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for the low-δ<sup>18</sup>O magmatism of the Snake River Plain–Yellowstone hotspot and other low-δ<sup>18</sup>O large igneous provinces」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

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