The magmatic architecture and evolution of the Chang’e-5 lunar basalts

Abstract

The lunar basalt samples returned by the Chang’e-5 mission erupted about 2.0 billion years ago during the late period of the Moon’s secular cooling. The conditions of mantle melting in the source region and the migration of magma through the thick lithosphere that led to this relatively late lunar volcanism remain open questions. Here we combine quantitative textural analyses of Chang’e-5 basaltic clasts, diffusion chronometry, clinopyroxene geothermobarometers and crystallization simulations to establish a holistic picture of the dynamic magmatic–thermal evolution of these young lunar basalts. We find that the Chang’e-5 basalts originated from an olivine-bearing pyroxenite mantle source (10–13 kbar or 250 ± 50 km; 1,350 ± 50 °C), similar to Apollo 12 low-Ti basalts. We propose these magmas then ascended through the plumbing system and accumulated mainly at the top of the lithospheric mantle (~2–5 kbar or 40–100 km, 1,150 ± 50 °C), where they stalled at least several hundred days and evolved via high-degree fractional crystallization. Finally, the remaining evolved melts erupted rapidly onto the surface over several days. Our magmatic–thermal evolution model indicates abundant low-solidus pyroxenites in the mantle source with a slightly enhanced inventory of radioactive elements can explain the prolonged, but declining, lunar volcanism up to about 2 billion years ago and beyond.

Full text

Nature Geoscience | Volume 16 | April 2023 | 301–308 301
nature geoscience
https://doi.org/10.1038/s41561-023-01146-x
Article
The magmatic architecture and evolution of
the Chang’e-5 lunar basalts
Biji Luo 1 , Zaicong Wang 1 , Jiale Song1, Yuqi Qian 1, Qi He1, Yiheng Li1,
James W. Head2, Frédéric Moynier 3, Long Xiao 1, Harry Becker4,
Bixuan Huang1, Bing Ruan1, Yangxuan Hu1, Fabing Pan1, Chang Xu1, Wenlong Liu1,
Keqing Zong1, Jiawei Zhao1, Wen Zhang1, Zhaochu Hu1, Zhenbing She 1,
Xiang Wu1 & Hongfei Zhang1
The lunar basalt samples returned by the Chang’e-5 mission erupted about
2.0 billion years ago during the late period of the Moon’s secular cooling.
The conditions of mantle melting in the source region and the migration
of magma through the thick lithosphere that led to this relatively late lunar
volcanism remain open questions. Here we combine quantitative textural
analyses of Chang’e-5 basaltic clasts, diusion chronometry, clinopyroxene
geothermobarometers and crystallization simulations to establish a
holistic picture of the dynamic magmatic–thermal evolution of these
young lunar basalts. We nd that the Chang’e-5 basalts originated from
an olivine-bearing pyroxenite mantle source (10–13 kbar or 250 ± 50 km;
1,350 ± 50 °C), similar to Apollo 12 low-Ti basalts. We propose these magmas
then ascended through the plumbing system and accumulated mainly at
the top of the lithospheric mantle (~2–5 kbar or 40–100 km, 1,150 ± 50 °C),
where they stalled at least several hundred days and evolved via high-degree
fractional crystallization. Finally, the remaining evolved melts erupted
rapidly onto the surface over several days. Our magmatic–thermal evolution
model indicates abundant low-solidus pyroxenites in the mantle source
with a slightly enhanced inventory of radioactive elements can explain the
prolonged, but declining, lunar volcanism up to about 2 billion years ago
and beyond.
Volcanism is the primary endogenic process of the terrestrial planets,
reflecting their internal thermal state and evolution1,2. Volcanic activity
on the Moon is the key record of its thermo-chemical evolution
3
. Lunar
mare basalts were erupted mainly in two major pulses of ~3.9–3.6 bil-
lion years ago (Ga) and ~3.4–3.1 Ga, significantly fewer were emplaced
between ~3.1 and 2.0 Ga as the lunar mantle cooled, and the process
finally ceased at ~1.2 Ga4–6. Available data suggested that the majority of
the lunar mare basalts were erupted in the Procellarum KREEP Terrane
(PKT), a region rich in potassium, rare-earth elements and phospho-
rus (KREEP)5,7. These observations have led to the hypothesis that the
elevated KREEP in mare basalt mantle sources was the heat source for
prolonging lunar volcanism
8,9
and, presumably, asymmetric thermal
evolution of the Moon10.
China’s Chang’e-5 (CE-5) mission landed in northern Oceanus
Procellarum within the PKT and sampled the youngest (~2.0 Ga) lunar
basalts radiometrically dated so far
11,12
. However, the mantle source
Received: 13 March 2022
Accepted: 16 February 2023
Published online: 20 March 2023
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1State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China.
2Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA. 3Institut de Physique du Globe de Paris, Université
Paris Cité, CNRS, UMR 7154, Paris, France. 4Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany. e-mail: luobj@cug.edu.cn;
zaicongwang@cug.edu.cn
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