Abstract

An igneous clast from the Northwest Africa 773 (NWA 773) clan of lunar meteorites formed by silicic volcanism on the Moon. The clast was identified in Northwest Africa 2727 (NWA 2727), which is included in the NWA 773 clan. Over 80 mode% of the clast consists of silica + plagioclase + K-Ba-feldspar. The silica phases cristobalite, tridymite, and quartz are all present in the clast, indicating rapid cooling at low pressure in agreement with a volcanic setting. This clast is characterized as a dacite on the basis of mineral modes and whole-rock chemical composition. Olivine and pyroxene in the clast have high Fe/Mg ratios (olivine Fe# > 99, pyroxene Fe# > 99; with Fe# = molar Fe/(Fe + Mg) × 100), suggesting crystallization from a residual liquid after fractionation of more magnesian silicates. The clast is similar in some respects to ferroan gabbro alkaline-phase-ferroan (FG/ARFe) clasts that are inferred to be co-magmatic with olivine gabbro (OG) and other mafic lithologies of the NWA 773 clan. However, the high silica concentration and dominance of apatite as the main Ca-phosphate (no merrillite was identified) are distinct from the FG/ARFe clasts. Thus, the dacite clast probably crystallized in a magmatic setting that was independent of the OG and FG/ARFe lithologies. The mafic major element composition, young age, and high KREEP-content of the NWA 773 clan have been used previously to infer an origin from the Procellarum-KREEP terrane (PKT) on the nearside of the Moon. Several candidates for silicic volcanism/plutonism have been identified in the PKT (e.g., Gruithuisen Domes, Hansteen alpha, Lassell Massif). The presence of the dacite lithology provides additional support for an origin in or around PKT for meteorites of the NWA 773 clan, and for complex igneous activity in PKT region.

Details

Title
Formation of ferroan dacite by lunar silicic volcanism recorded in a meteorite from the Moon
Author
Nagaoka, Hiroshi 1   VIAFID ORCID Logo  ; Fagan, Timothy J 2 ; Kayama Masahiro 3 ; Karouji Yuzuru 4 ; Hasebe Nobuyuki 5 ; Ebihara Mitsuru 2 

1  Waseda University, Research Institute for Science and Engineering, Tokyo, Japan (GRID:grid.5290.e) (ISNI:0000 0004 1936 9975); Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Sagamihara, Japan (GRID:grid.62167.34) (ISNI:0000 0001 2220 7916) 
2  Waseda University, Department of Earth Science, School of Education, Tokyo, Japan (GRID:grid.5290.e) (ISNI:0000 0004 1936 9975) 
3  Tohoku University, Department of Earth and Planetary Materials Science, Graduate School of Science, Sendai, Japan (GRID:grid.69566.3a) (ISNI:0000 0001 2248 6943); Tohoku University, Creative Interdisciplinary Research Division, Frontier Research Institute for Interdisciplinary Sciences, Sendai, Japan (GRID:grid.69566.3a) (ISNI:0000 0001 2248 6943); The University of Tokyo, Department of General Systems Studies, Graduate School of Arts and Sciences, Tokyo, Japan (GRID:grid.26999.3d) (ISNI:0000 0001 2151 536X) 
4  Japan Aerospace Exploration Agency, JAXA Space Exploration Center, Sagamihara, Japan (GRID:grid.62167.34) (ISNI:0000 0001 2220 7916) 
5  Waseda University, Research Institute for Science and Engineering, Tokyo, Japan (GRID:grid.5290.e) (ISNI:0000 0004 1936 9975); Waseda University, School Advanced Science and Engineering, Tokyo, Japan (GRID:grid.5290.e) (ISNI:0000 0004 1936 9975) 
Publication year
2020
Publication date
Dec 2020
Publisher
Springer Nature B.V.
e-ISSN
21974284
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1186/s40645-020-0324-8
ProQuest document ID
2369722687
Copyright
Progress in Earth and Planetary Science is a copyright of Springer, (2020). All Rights Reserved. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.