HKU Geologists Uncover Extensive Intrusive Magmatism at Chang'e-6 Lunar Site

HKU Geologists Uncover Extensive Intrusive Magmatism at Chang'e-6 Lunar Site
by Simon Mansfield
Sydney, Australia (SPX) Aug 30, 2024

Lunar igneous activities, including both intrusive and extrusive magmatism, offer crucial insights into the Moon's interior and its thermal history. These activities are distributed asymmetrically between the Moon's nearside and farside, reflecting the global lunar dichotomy. Previous lunar samples returned by Apollo, Luna, and Chang'e-5 missions all originated from the nearside, leaving a gap in understanding the farside, particularly within the South Pole-Aitken (SPA) basin. This basin is considered key to addressing the asymmetry in lunar data and unraveling the mysteries of the lunar dichotomy.

The Chang'e-6 mission, part of China's Lunar Exploration Program, launched on May 3, 2024, successfully landed on the Moon's farside on June 2, and returned to Earth on June 25 with 1935.3 grams of lunar soil. This mission marks the first successful sample return from the Moon's farside, specifically from the southern Apollo basin within the SPA basin. These samples are expected to provide significant new data, potentially reshaping our understanding of the Moon. However, the less understood intrusive magmatic activities, compared to the more visible mare volcanism around the Chang'e-6 landing site, pose challenges for future sample analysis.

In a recent study published in 'The Astrophysical Journal Letters', Dr. Yuqi Qian, Professor Joseph Michalski, and Professor Guochun Zhao from the Department of Earth Sciences at The University of Hong Kong (HKU), along with their collaborators, conducted a comprehensive analysis of the intrusive magmatism at the Chang'e-6 landing site and its surroundings using remote sensing data. Their research uncovered extensive distributions of intrusive magmatism, providing new insights into the formation of lunar plutonic rocks and the implications for the Chang'e-6 mission, which will support further studies of the Moon's farside.

Key Findings:

The study revealed that intrusive magmatism is prevalent in the SPA basin, manifesting in various forms such as sills beneath modified crater floors, linear and ring dikes detected through gravity data, and Mg-suite intrusions identified by their spectral characteristics. These features align with the intermediate-thick crust of the SPA basin, which favors intrusion. The Chang'e-6 mission likely collected plutonic rocks transported by nearby impact craters, which could be analyzed in ongoing sample studies. The discovery of heavily degraded floor-fractured craters, such as Apollo X and Apollo Q, suggests the presence of more similar features across the Moon, indicating the abundance of intrusive magmatism in the region.

The research also traced potential plutonic materials within the Chang'e-6 samples, finding that Mg-suite materials, likely originating from the western peak ring of the Apollo basin and delivered by the Chaffee S crater, could be present. These Mg-rich materials are essential for understanding the origins of KREEP-poor Mg-suite rocks, which remain a mystery. Analyzing samples from both intrusive and extrusive magmatism on the previously unexplored farside, especially the Mg-suite, could provide critical insights into the lunar dichotomy and fundamental questions about the Moon's secondary crust formation and early evolution.

Professor Xianhua Li, a leader in China's lunar sample studies from the Institute of Geology and Geophysics at the Chinese Academy of Sciences (CAS), emphasized the importance of this research: "The results of this research set a significant geological framework to study plutonic rocks in the Chang'e-6 samples, especially Mg-suite rocks. Their petrogenesis and timing are unclear, and this research would dramatically help to understand their origin mechanism."

"This research is an excellent example of HKU's deep involvement in the China's Lunar Exploration Program," said Professor Guochun Zhao, an academician of the Chinese Academy of Science and Chair Professor of Earth Sciences at HKU. "Lunar and space exploration programs are an important component of China's goal to become a scientific and technological power, and HKU's proactive involvement in these programs will bring additional resources for Hong Kong to become an international centre for science and innovation."

HKU, the first university in Hong Kong to possess lunar samples from the Chang'e-5 mission, will continue to seek opportunities to study Chang'e-6 samples and further engage in China's Lunar Exploration Program.

For more information about Dr. Qian, please visit here and for Professor Michalski, please visit here

Research Report:Extensive Intrusive Magmatism in the Lunar Farside Apollo and South Pole-Aitken Basins, Chang'e-6 Landing Site