Age of graben systems on the moon

The study focuses on the time of formation of the graben. An attempt is made to determine whether the graben are restricted to geologic units of certain ages, and whether and at what time graben formation ceased. It is shown that (1) most preserved graben formed considerably later than the impacts that formed the basins; (2) graben are faults that are reactivated along older basin concentric and radial structures and lunar grid directions; (3) graben formation ceased about 3.6 + or - 0.2 b.y. ago; and (4) graben formation reflects a tensile stress fields that obtained during part of early lunar history. Other features of graben systems on the moon are also identified.