In February 2021, the Chinese Chang'e 5 spacecraft launched from the Moon, carrying a precious cargo of lunar rocks. Scientists have studied these rocks for the past four years, attempting to reconstruct the region's volcanic history. In general, they found that the large-scale flood basalts (known as mare) in this area are about two billion years old, young by mare basalt standards. More recently, small bits of pyroclastic (explosive volcanism) material were dated around 125 million years old.
One of the early findings from the LRO mission was the discovery of volcanic features known as Irregular Mare Patches (IMPs) scattered across the nearside. These landforms are generally considered volcanic. However, their ages are hotly debated. They may be as young as 50 million years or as old as 3.5 billion years. The Aristarchus IMP (25.045°N, 313.233°E) is one of the smallest and most enigmatic IMP. The fact that this IMP is found within the Aristarchus crater ejecta suggests it formed after the crater, which is dated at 200 million years.
Alternatively, this IMP may have formed as part of ejecta emplacement from the Aristarchus crater forming impact. However, no other crater ejecta on the Moon exhibits a similar landform.
The exciting new results from the Chang'e 5 mission may tilt the scales in favor of young lunar volcanism. However, more work can be done from existing science observations, returned samples, and future landed missions. In fact, NASA is planning a CLPS mission to the most well-known IMP, Ina or Ina-D (due to its distinctive "D"-shape). Its primary payload, DIMPLE, will attempt to measure the age of the basalt within Ina, the first-ever in-situ radiometric age dating experiment on the Moon.
NAC M1453037761LR, north is up, 1.6 meter pixels, full image width 6000 meters at center [NASA/GSFC/Intuitive Machines].
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New Evidence for Young Lunar Volcanism
Published by Mark Robinson on 18 October 2024