A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units

Nick Dygert; Jung Fu Lin; Edward W. Marshall; Yoshio Kono; James E. Gardner

doi:10.1002/2017GL075703

A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units

Nick Dygert, Jung Fu Lin, Edward W. Marshall, Yoshio Kono, James E. Gardner

Science Institute

University of Iceland

Research output: Contribution to journal › Article › peer-review

Abstract

Much of the lunar crust is monomineralic, comprising >98% plagioclase. The prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean (LMO). Whether >98% pure anorthosites can form in a flotation scenario is debated. An important determinant of the efficiency of plagioclase fractionation is the viscosity of the LMO liquid, which was unconstrained. Here we present results from new experiments conducted on a late LMO-relevant ferrobasaltic melt. The liquid has an exceptionally low viscosity of 0.22_-0.29^+0.11 to 1.45_-0.82^+0.46 Pa s at experimental conditions (1,300–1,600°C; 0.1–4.4 GPa) and can be modeled by an Arrhenius relation. Extrapolating to LMO-relevant temperatures, our analysis suggests a low viscosity LMO would form a stratified flotation crust, with the oldest units containing a mafic component and with very pure younger units. Old, impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario.

Original language	English
Pages (from-to)	11,282-11,291
Journal	Geophysical Research Letters
Volume	44
Issue number	22
DOIs	https://doi.org/10.1002/2017GL075703
Publication status	Published - 28 Nov 2017

Bibliographical note

Funding Information: We thank Kerri Donaldson Hanna and an anonymous reviewer for comments that significantly improved this manu script. This work was supported by a postdoctoral fellowship to N. D. by the Jackson School of Geosciences. The experiments were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operation is supported by DOE- NNSA under award DE-NA0001974, with partial instrumentation funding by NSF. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract DE- AC02-06CH11357. J. F. L acknowledges support from NSF Geophysics Program and Extreme Physics and Chemistry Program of the Deep Carbon Observatory. Y. K. acknowledges the support of DOE-BES/DMSE under award DE-FG02-99ER45775 and support by the National Science Foundation under award EAR-1722495. J. E. G. acknowl edges support by the National Science Foundation under award OCE-1333882. Raw experimental data are available on request to N. D. Publisher Copyright: ©2017. American Geophysical Union. All Rights Reserved.

Other keywords

Paris-Edinburgh
flotation crust
lunar magma ocean
plagioclase
viscometry
viscosity

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10.1002/2017GL075703

Moon's crust underwent resurfacing after forming from magma ocean
Marshall, E. W.
21/11/17 → 23/11/17
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University of Iceland
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@article{de2fa9af06f54c408e7147edbdc5900c,

title = "A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units",

abstract = "Much of the lunar crust is monomineralic, comprising >98\% plagioclase. The prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean (LMO). Whether >98\% pure anorthosites can form in a flotation scenario is debated. An important determinant of the efficiency of plagioclase fractionation is the viscosity of the LMO liquid, which was unconstrained. Here we present results from new experiments conducted on a late LMO-relevant ferrobasaltic melt. The liquid has an exceptionally low viscosity of 0.22-0.29+0.11 to 1.45-0.82+0.46 Pa s at experimental conditions (1,300–1,600°C; 0.1–4.4 GPa) and can be modeled by an Arrhenius relation. Extrapolating to LMO-relevant temperatures, our analysis suggests a low viscosity LMO would form a stratified flotation crust, with the oldest units containing a mafic component and with very pure younger units. Old, impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario.",

keywords = "Paris-Edinburgh, flotation crust, lunar magma ocean, plagioclase, viscometry, viscosity",

author = "Nick Dygert and Lin, \{Jung Fu\} and Marshall, \{Edward W.\} and Yoshio Kono and Gardner, \{James E.\}",

note = "Funding Information: We thank Kerri Donaldson Hanna and an anonymous reviewer for comments that significantly improved this manu script. This work was supported by a postdoctoral fellowship to N. D. by the Jackson School of Geosciences. The experiments were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operation is supported by DOE- NNSA under award DE-NA0001974, with partial instrumentation funding by NSF. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract DE- AC02-06CH11357. J. F. L acknowledges support from NSF Geophysics Program and Extreme Physics and Chemistry Program of the Deep Carbon Observatory. Y. K. acknowledges the support of DOE-BES/DMSE under award DE-FG02-99ER45775 and support by the National Science Foundation under award EAR-1722495. J. E. G. acknowl edges support by the National Science Foundation under award OCE-1333882. Raw experimental data are available on request to N. D. Publisher Copyright: {\textcopyright}2017. American Geophysical Union. All Rights Reserved.",

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journal = "Geophysical Research Letters",

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T1 - A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units

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AU - Lin, Jung Fu

AU - Marshall, Edward W.

AU - Kono, Yoshio

AU - Gardner, James E.

N1 - Funding Information: We thank Kerri Donaldson Hanna and an anonymous reviewer for comments that significantly improved this manu script. This work was supported by a postdoctoral fellowship to N. D. by the Jackson School of Geosciences. The experiments were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operation is supported by DOE- NNSA under award DE-NA0001974, with partial instrumentation funding by NSF. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract DE- AC02-06CH11357. J. F. L acknowledges support from NSF Geophysics Program and Extreme Physics and Chemistry Program of the Deep Carbon Observatory. Y. K. acknowledges the support of DOE-BES/DMSE under award DE-FG02-99ER45775 and support by the National Science Foundation under award EAR-1722495. J. E. G. acknowl edges support by the National Science Foundation under award OCE-1333882. Raw experimental data are available on request to N. D. Publisher Copyright: ©2017. American Geophysical Union. All Rights Reserved.

PY - 2017/11/28

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N2 - Much of the lunar crust is monomineralic, comprising >98% plagioclase. The prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean (LMO). Whether >98% pure anorthosites can form in a flotation scenario is debated. An important determinant of the efficiency of plagioclase fractionation is the viscosity of the LMO liquid, which was unconstrained. Here we present results from new experiments conducted on a late LMO-relevant ferrobasaltic melt. The liquid has an exceptionally low viscosity of 0.22-0.29+0.11 to 1.45-0.82+0.46 Pa s at experimental conditions (1,300–1,600°C; 0.1–4.4 GPa) and can be modeled by an Arrhenius relation. Extrapolating to LMO-relevant temperatures, our analysis suggests a low viscosity LMO would form a stratified flotation crust, with the oldest units containing a mafic component and with very pure younger units. Old, impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario.

AB - Much of the lunar crust is monomineralic, comprising >98% plagioclase. The prevailing model argues the crust accumulated as plagioclase floated to the surface of a solidifying lunar magma ocean (LMO). Whether >98% pure anorthosites can form in a flotation scenario is debated. An important determinant of the efficiency of plagioclase fractionation is the viscosity of the LMO liquid, which was unconstrained. Here we present results from new experiments conducted on a late LMO-relevant ferrobasaltic melt. The liquid has an exceptionally low viscosity of 0.22-0.29+0.11 to 1.45-0.82+0.46 Pa s at experimental conditions (1,300–1,600°C; 0.1–4.4 GPa) and can be modeled by an Arrhenius relation. Extrapolating to LMO-relevant temperatures, our analysis suggests a low viscosity LMO would form a stratified flotation crust, with the oldest units containing a mafic component and with very pure younger units. Old, impure crust may have been buried by lower crustal diapirs of pure anorthosite in a serial magmatism scenario.

KW - Paris-Edinburgh

KW - flotation crust

KW - lunar magma ocean

KW - plagioclase

KW - viscometry

KW - viscosity

UR - https://www.scopus.com/pages/publications/85034639505

U2 - 10.1002/2017GL075703

DO - 10.1002/2017GL075703

M3 - Article

SN - 0094-8276

VL - 44

SP - 11,282-11,291

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 22

ER -

A Low Viscosity Lunar Magma Ocean Forms a Stratified Anorthitic Flotation Crust With Mafic Poor and Rich Units

Abstract

Bibliographical note

Other keywords

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Moon's crust underwent resurfacing after forming from magma ocean

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