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Open AccessArticle

The Viscosity and Atomic Structure of Volatile-Bearing Melilititic Melts at High Pressure and Temperature and the Transport of Deep Carbon

1
Department of Earth Sciences, Sapienza University of Rome, 00185 Rome, Italy
2
National Institute of Geophysics and Volcanology, 00143 Rome, Italy
3
Geodynamics Research Center, Ehime University, 790-8577 Matsuyama, Japan
4
INFN National Institute of Nuclear Physics, 00185 Rome, Italy
5
CNR-IOM and Department of Physics, Sapienza University of Rome, 00185 Rome, Italy
6
Department of Sciences, University of Studies Roma Tre, L.go San Leonardo Murialdo 1, 00146 Rome, Italy
7
Department of Engineering and Geology, University of Chieti-Pescara, 66013 Chieti Scalo, Italy
8
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
9
Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, CA 90095, USA
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(3), 267; https://doi.org/10.3390/min10030267 (registering DOI)
Received: 5 February 2020 / Revised: 13 March 2020 / Accepted: 14 March 2020 / Published: 16 March 2020
Understanding the viscosity of mantle-derived magmas is needed to model their migration mechanisms and ascent rate from the source rock to the surface. High pressure–temperature experimental data are now available on the viscosity of synthetic melts, pure carbonatitic to carbonate–silicate compositions, anhydrous basalts, dacites and rhyolites. However, the viscosity of volatile-bearing melilititic melts, among the most plausible carriers of deep carbon, has not been investigated. In this study, we experimentally determined the viscosity of synthetic liquids with ~31 and ~39 wt% SiO2, 1.60 and 1.42 wt% CO2 and 5.7 and 1 wt% H2O, respectively, at pressures from 1 to 4.7 GPa and temperatures between 1265 and 1755 °C, using the falling-sphere technique combined with in situ X-ray radiography. Our results show viscosities between 0.1044 and 2.1221 Pa·s, with a clear dependence on temperature and SiO2 content. The atomic structure of both melt compositions was also determined at high pressure and temperature, using in situ multi-angle energy-dispersive X-ray diffraction supported by ex situ microFTIR and microRaman spectroscopic measurements. Our results yield evidence that the T–T and T–O (T = Si,Al) interatomic distances of ultrabasic melts are higher than those for basaltic melts known from similar recent studies. Based on our experimental data, melilititic melts are expected to migrate at a rate ~from 2 to 57 km·yr−1 in the present-day or the Archaean mantle, respectively. View Full-Text
Keywords: viscosity; melt structure; high pressure; falling-sphere technique; ultrabasic melt; Paris–Edinburgh press; magma ascent rate; migration rate viscosity; melt structure; high pressure; falling-sphere technique; ultrabasic melt; Paris–Edinburgh press; magma ascent rate; migration rate
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Stagno, V.; Stopponi, V.; Kono, Y.; D’Arco, A.; Lupi, S.; Romano, C.; Poe, B.T.; Foustoukos, D.I.; Scarlato, P.; Manning, C.E. The Viscosity and Atomic Structure of Volatile-Bearing Melilititic Melts at High Pressure and Temperature and the Transport of Deep Carbon. Minerals 2020, 10, 267.

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