James McLelland, Jeffrey Chiarenzelli, Philip Whitney, Yngvar Isachsen; U-Pb zircon geochronology of the Adirondack Mountains and implications for their geologic evolution. Geology ; 16 (10): 920–924. doi: https://doi.org/10.1130/0091-7613(1988)016<0920:UPZGOT>2.3.CO;2
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U-Pb zircon studies of metamorphosed igneous rocks in the Adirondack Mountains have yielded preliminary ages within the range 1420-990 Ma. Several geochronologically and geochemically distinct episodes of igneous intrusion and at least one pre-granulite facies dynamothermal metamorphic event are documented. This information is consistent with recent field and geochronological studies throughout the Grenville province and suggests that a complex sequence of events occurred in the Adirondack Mountains prior to the widespread deformation and metamorphism commonly attributed to the ∼1100-1000 Ma Ottawan phase of the Grenvillian orogenic cycle.