Transient rhyolite melt extraction to produce a shallow granitic pluton

Allen J Schaen; Blair Schoene; Josef Dufek; Brad S Singer; Michael P Eddy; Brian R Jicha; John M Cottle

doi:10.1126/sciadv.abf0604

Transient rhyolite melt extraction to produce a shallow granitic pluton

Sci Adv. 2021 May 19;7(21):eabf0604. doi: 10.1126/sciadv.abf0604. Print 2021 May.

Authors

Allen J Schaen¹, Blair Schoene², Josef Dufek³, Brad S Singer⁴, Michael P Eddy⁵, Brian R Jicha⁴, John M Cottle⁶

Affiliations

¹ Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA. ajschaen@arizona.edu.
² Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
³ Earth Sciences Department, University of Oregon, Eugene, OR 97403, USA.
⁴ Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA.
⁵ Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA.
⁶ Department of Earth Science, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.

Abstract

Rhyolitic melt that fuels explosive eruptions often originates in the upper crust via extraction from crystal-rich sources, implying an evolutionary link between volcanism and residual plutonism. However, the time scales over which these systems evolve are mainly understood through erupted deposits, limiting confirmation of this connection. Exhumed plutons that preserve a record of high-silica melt segregation provide a critical subvolcanic perspective on rhyolite generation, permitting comparison between time scales of long-term assembly and transient melt extraction events. Here, U-Pb zircon petrochronology and ⁴⁰Ar/³⁹Ar thermochronology constrain silicic melt segregation and residual cumulate formation in a ~7 to 6 Ma, shallow (3 to 7 km depth) Andean pluton. Thermo-petrological simulations linked to a zircon saturation model map spatiotemporal melt flux distributions. Our findings suggest that ~50 km³ of rhyolitic melt was extracted in ~130 ka, transient pluton assembly that indicates the thermal viability of advanced magma differentiation in the upper crust.

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