If the missing rings are real but vary by region then you should be able to do regional reconstructions that show dramatic responses to
the volcanic events in some regions (that didn't miss), and much smaller response in others (where the ring was missed).
Here we combine new and published geochronological data for tectonic - magmatic
events recorded along the Greenland continental rifted margin to test the hypothesis that the origin of the main Cenozoic hyperthermals, including the PETM, is rooted
in plate tectonic, metamorphic and
volcanic processes
in the North Atlantic
region.