Complete hydrothermal re-equilibration of zircon in the Maniitsoq structure, West Greenland: A 3001Ma minimum age of impact?
Zircon in five samples of variably comminuted, melted, and hydrothermally altered orthogneiss from the Maniitsoq structure of southern West Greenland yield a weighted mean 207Pb/206Pb age of 3000.9 +/- 1.9Ma (ion probe data, n=37). The age data constitute a rare example of pervasive and nearly complete isotopic resetting of zircon during a regional hydrothermal event. Many zircon grains are homoge