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New U/Pb Ages from Granite and Granite Gneiss in the Ruby Geanticline and Southern Brooks Range, Alaska
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1987
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EngineeringPrecambrian GeologyRay MountainsGeologic Time ScaleEarth ScienceSocial SciencesCentral AlaskaRegional GeologyNew U/pb AgesQuaternary ResearchGeological DataMesozoic TectonicsGeochronologyGeographyGeologyTectonicsU/pb Zircon AgesSouthern Brooks RangeHistory Of GeologyEconomic GeologyGranite GneissPaleoecologyPetrologyQuaternary Period
New U/Pb zircon ages from the Ray Mountains of central Alaska clarify the plutonic history of the Ruby geanticline and support earlier suggestions that the Ruby geanticline and southern Brooks Range were once parts of the same tectonostratigraphic terrane. U/Pb zircon ages of 109 to 112 Ma from the Ray Mountains pluton confirm previously reported mid-Cretaceous K/Ar ages and rule out the possibility that the earliest intrusive phase of the pluton is older than mid-Cretaceous. New U/Pb zircon ages from four granite gneiss samples in the Ray Mountains indicate a Devonian protolith age of 390 ± 12 Ma and suggest that the Ruby geanticline, like the southern Brooks Range, underwent a major plutonic event in mid-Paleozoic time.