Replication Data for "Dating the Ames Astrobleme, Oklahoma, USA: A possible new link to the Late Devonian"

The Ames impact structure (Oklahoma) is a buried, oil-producing crater. Conodont biostratigraphy of the crater fill indicates a Late Ordovician age, consistent with formation during the Ordovician Meteor Event triggered by the fragmentation of the parent L-chondrite asteroid. U–Pb zircon dates from its impact melt portion, conducted using Secondary Ion Mass Spectrometry and Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (n = 37 spots), yield a Mesoproterozoic emplacement age of the impacted granodiorite (1411 ± 23 Ma, ±2σ). However, Concordia regression defines a lower intercept of 374.9 ± 5.3 Ma. Cathodoluminescence and electron backscattered diffraction images reveal that most zircons, including the youngest Devonian-age grains, show primary oscillatory zoning and lack deformation, consistent with melt crystallization. However, two have clear impact-related textures, including regions of low-angle grain boundaries within microcracks and discrete arrays of granular zircon grains crosscutting oscillatory growth zoning. Plagioclase (n = 6 samples, 40Ar/39Ar) yields Late Carboniferous (~320.3 Ma) and Permian (267.3 ± 1.6 Ma) dates, likely related to hydrothermal alteration and coincident with the thermal maturation of hydrocarbons in the crater. Based on the youngest zircon dates, the Ames impact structure may record activity near the Frasnian–Famennian boundary, contemporaneous with other North American impacts.