NASA has released a photograph taken from the International Space Station showing an anorthosite massif located in the arid southern region of Madagascar, which resembles the lunar surface. This intrusive igneous rock, formed by the cooling of magma beneath the surface, is common on the Moon where it constitutes the highly reflective lunar highlands.
The Saririaky massif in Madagascar, visible over approximately 100 square kilometers, formed in the Late Precambrian, at least 600 million years ago. It is situated within a ductile shear zone, where high pressures and temperatures metamorphosed surrounding rocks, creating north-south linear patterns.
Geologists believe this deformation resulted from the collision of continental plates forming the supercontinent Gondwana, involving Africa, India, Madagascar, Australia, and Antarctica. A neighboring anorthosite massif was likely separated from Saririaky during this process, forming a structure known as boudinage.
Terrestrial anorthosites, such as those in Madagascar or the Beartooth Mountains in the United States, serve as comparisons for studying lunar anorthosites, which are over 4 billion years old and compose the Moon’s outer crust. This research aids in understanding the Moon’s geological history beyond the limited samples returned by the Apollo missions.