Rights statement: This is the author’s version of a work that was accepted for publication in Earth and Planetary Science Letters. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Earth and Planetary Science Letters, 564, 2021 DOI: 10.1016/j.epsl.2021.116907
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Degassing of volcanic extrusives on Mercury
T2 - Potential contributions to transient atmospheres and buried polar deposits
AU - Deutsch, A.N.
AU - Head, J.W.
AU - Parman, S.W.
AU - Wilson, L.
AU - Neumann, G.A.
AU - Lowden, F.
N1 - This is the author’s version of a work that was accepted for publication in Earth and Planetary Science Letters. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Earth and Planetary Science Letters, 564, 2021 DOI: 10.1016/j.epsl.2021.116907
PY - 2021/6/15
Y1 - 2021/6/15
N2 - The surface of Mercury is dominated by extensive, widespread lava plains that formed early in its history. The emplacement of these lavas was accompanied by the release of magmatic volatiles, the bulk of which were lost to space via thermal escape and/or photodissociation. Here we consider the fate of these erupted volatiles by quantifying the volumes of erupted volcanic plains and estimating the associated masses of erupted volatiles. The concentrations and speciation of volatiles in Mercury's magmas are not known with certainty at this time, so we model a wide range of cases, based on existing experimental data and speciation models, at 3–7 log fO2 units below conditions determined by the iron-wüstite buffer. Cases range from relatively low gas content scenarios (total exsolved gas mass of 9×1015 kg) to high gas content scenarios (total exsolved gas = 5 × 1019 kg). We estimate that the average duration of a transient volcanic atmosphere resulting from a single eruption would be between ∼250 and ∼210,000 years, depending on the volume, degassed volatile content, and eruption rate of an individual eruption, as well as the fO2 conditions of the planet's interior. If a dense transient atmosphere was ever surface-bound long enough for the released volatiles to be transported to and cold-trapped at Mercury's polar regions, those trapped volatiles are predicted to be well-mixed with the regolith, and at least 16 m beneath the surface given regolith gardening rates. These volatiles would have a composition and age distinctly different from those of the H2O-ice deposits observed at the poles of Mercury today. © 2021 Elsevier B.V.
AB - The surface of Mercury is dominated by extensive, widespread lava plains that formed early in its history. The emplacement of these lavas was accompanied by the release of magmatic volatiles, the bulk of which were lost to space via thermal escape and/or photodissociation. Here we consider the fate of these erupted volatiles by quantifying the volumes of erupted volcanic plains and estimating the associated masses of erupted volatiles. The concentrations and speciation of volatiles in Mercury's magmas are not known with certainty at this time, so we model a wide range of cases, based on existing experimental data and speciation models, at 3–7 log fO2 units below conditions determined by the iron-wüstite buffer. Cases range from relatively low gas content scenarios (total exsolved gas mass of 9×1015 kg) to high gas content scenarios (total exsolved gas = 5 × 1019 kg). We estimate that the average duration of a transient volcanic atmosphere resulting from a single eruption would be between ∼250 and ∼210,000 years, depending on the volume, degassed volatile content, and eruption rate of an individual eruption, as well as the fO2 conditions of the planet's interior. If a dense transient atmosphere was ever surface-bound long enough for the released volatiles to be transported to and cold-trapped at Mercury's polar regions, those trapped volatiles are predicted to be well-mixed with the regolith, and at least 16 m beneath the surface given regolith gardening rates. These volatiles would have a composition and age distinctly different from those of the H2O-ice deposits observed at the poles of Mercury today. © 2021 Elsevier B.V.
KW - atmospheres
KW - Mercury
KW - Moon
KW - polar deposits
KW - volcanism
KW - Earth atmosphere
KW - Mercury (metal)
KW - Photodissociation
KW - Volcanoes
KW - Case based
KW - Condition
KW - Extrusives
KW - Gas content
KW - Magmatic volatiles
KW - Polar deposits
KW - Thermal escape
KW - Volcanics
KW - Volcanism
KW - Deposits
U2 - 10.1016/j.epsl.2021.116907
DO - 10.1016/j.epsl.2021.116907
M3 - Journal article
VL - 564
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
M1 - 116907
ER -