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Creator |
1c5c32b11b5ad1bd9c846a77784abc38 |
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Creator |
b75227dc49245aab76a534b836099ab7 |
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Creator |
5a9f28970e2d0d0ba76f7ab60ee890ba |
| 70987 |
Creator |
ba8360878cb51bc013a9bf0e41d92226 |
| 70987 |
Creator |
535569f047a5e8d3192793448a2322e2 |
| 70987 |
Creator |
ext-05ac45a05f79d0ec0be086dbf479a7f1 |
| 70987 |
Creator |
ext-b7c19bde1d89dc871d7177785b06ce2f |
| 70987 |
Creator |
ext-c954c42e9ff325887555f4250955a9ef |
| 70987 |
Creator |
ext-e2a4cf9a0eb8d1ddfa89264a4ac1af13 |
| 70987 |
Date |
2020-06-22 |
| 70987 |
Is Part Of |
p0012821X |
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Is Part Of |
repository |
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abstract |
Spurred by the discovery of water in lunar volcanic glasses about a decade ago, the
accessory mineral apatite became the primary target to investigate the abundance and
source of lunar water. This is due to its ability to contain significant amounts of
OH in its structure, along with the widespread presence of apatite in lunar rocks.
There is a general understanding that crustal cumulate rocks of the lunar magnesian
(Mg) suite are better candidates for recording the original isotopic compositions
of volatile elements in their parental melts compared to eruptive rocks, such as mare
basalts. Consequently, water-bearing minerals in Mg-suite rocks are thought to be
ideal candidates for discerning the primary hydrogen isotopic composition of water
in the lunar interior. Mg-suite rocks and most other Apollo samples that were collected
at the lunar surface display variable degrees of shock-deformation. In this study,
we have investigated seven Apollo 17 Mg-suite samples that include troctolite, gabbro
and norite lithologies, in order to understand if shock processes affected the water
abundances and/or H isotopic composition of apatite. The measured water contents in
apatite grains range from 31 to 964 ppm, with associated δD values varying between
−535 ±134‰ and +147 ±194‰(2σ). Considering the full dataset, there appears to be no
correlation between H2O and δD of apatite and the level of shock each apatite grain
has experienced. However, the lowest δD was recorded by individual, water-poor (<∼100
ppm H2O) apatite grains that are either directly in contact with an impact melt or
in its proximity. Therefore, the low-δD signature of apatite could be a result of
interactions with D-poor regolith (solar wind derived H), facilitated by shock-induced
nanostructures that could have provided pathways for migration of volatiles. In contrast,
in relatively water-rich apatites (>∼100 ppm H2O), regardless of the complexity of
the shock-induced nanostructures, there appears to be no evidence of water-loss or
alteration in their δD. The weighted average δD value of 24 such water-rich apatites
is −192 ±71‰, and, of all 36 analyzed spots is −209 ±47‰, indistinguishable from that
of other KREEPy lunar lithologies or the Earth’s deep mantle. Despite experiencing
variable degrees of shock-deformation at a later stage in lunar history, water-rich
apatite in some of the earliest-formed lunar crustal material appears to retain the
original isotopic signature of H in the Moon. |
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authorList |
authors |
| 70987 |
status |
peerReviewed |
| 70987 |
uri |
http://data.open.ac.uk/oro/document/1156053 |
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uri |
http://data.open.ac.uk/oro/document/1156059 |
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uri |
http://data.open.ac.uk/oro/document/1156064 |
| 70987 |
uri |
http://data.open.ac.uk/oro/document/1156065 |
| 70987 |
uri |
http://data.open.ac.uk/oro/document/1156066 |
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uri |
http://data.open.ac.uk/oro/document/1156067 |
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uri |
http://data.open.ac.uk/oro/document/1156816 |
| 70987 |
volume |
544 |
| 70987 |
type |
AcademicArticle |
| 70987 |
type |
Article |
| 70987 |
label |
Cernok, Ana ; Anand, Mahesh ; Zhao, Xuchao ; Darling, James R.; White, Lee F.; Stephant,
Alice ; Dunlop, Joseph; Tait, Kimberly T. and Franchi, Ian (2020). Preservation
of primordial signatures of water in highly-shocked ancient lunar rocks. Earth and
Planetary Science Letters, 544, article no. 116364. |
| 70987 |
Title |
Preservation of primordial signatures of water in highly-shocked ancient lunar rocks |
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in dataset |
oro |