Cryptomare magmatism 4.35 Gyr ago recorded in lunar meteorite Kalahari 009

Once on a new Moon The origin and evolution of the Moon remain controversial, one notable point of controversy being the timing of the beginning and end of basaltic volcanism in the lunar mares, or plains. Lunar research over the past three decades has suggested that mare volcanism occurred mainly after the late heavy bombardment that ended 3.9 billion years ago, because most of known mare basalts (lunar meteorites and returned Apollo and Luna samples), and remote sensing data, indicate crystallization ages younger than 3.9 billion years. But a new U–Pb dating of minerals in the lunar meteorite Kalahari 009 gives an age of roughly 4.35 billion years for a lunar basalt. This suggests that the volcanism started as early as 4.35 billion years ago, relatively soon after lunar formation and differentiation, and that Kalahari 009 is our first sample of a 'cryptomare' from the Moon.