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Snake River Plain – Yellowstone silicic volcanism: implications for magma genesis and magma fluxes

By
William P. Leeman
William P. Leeman
National Science Foundation, Earth Sciences Division, 4201 Wilson Blvd, Arlington, VA 22330, USA (e-mail: wleeman@nsf.gov)
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Catherine Annen
Catherine Annen
Départment de Minéralogie, University of Geneva, 1205 Geneva, Switzerland
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Josef Dufek
Josef Dufek
Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
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Published:
January 01, 2008

Abstract

The origin of large-volume, high-temperature silicic volcanism associated with onset of the Snake River Plain – Yellowstone (SRPY) hotspot track is addressed based on evolution of the well-characterized Miocene Bruneau–Jarbidge (BJ) eruptive centre. Although O–Sr–Pb isotopic and bulk compositions of BJ rhyolites exhibit strong crustal affinity, including strong 18O-depletion, Nd isotopic data preclude wholesale melting of ancient basement rocks and implicate involvement of a juvenile component – possibly derived from contemporaneous basaltic magmas. Several lines of evidence, including limits on 18O-depletion of the rhyolite source rocks due to influx of meteoric/hydrothermal fluids, constrain rhyolite generation to depths shallower than mid-upper crust (<20 km depth). For crustal melting driven by basaltic intrusions, sustenance of temperatures exceeding 900 °C at such depths over the life of the BJ eruptive centre requires incremental intrusion of approximately 16 km of basalt into the crust. This minimum basaltic flux (c. 4 mm year−1) is about one-tenth that at Kilauea. Nevertheless, emplacement of such volumes of magma in the crust creates a serious room problem, requiring that the crust must undergo significant extensional deformation – seemingly exceeding present estimates of extensional strain for the SRPY province.

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Contents

Geological Society, London, Special Publications

Dynamics of Crustal Magma Transfer, Storage and Differentiation

Catherine Annen
Catherine Annen
University of Geneva, Switzerland
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Georg F. Zellmer
Georg F. Zellmer
Academia Sinica, Taipei, Taiwan
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Geological Society of London
Volume
304
ISBN electronic:
9781862395527
Publication date:
January 01, 2008

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