TY - JOUR
T1 - An (U-Th)/He age for the shallow-marine Wetumpka impact structure, Alabama, USA
AU - Wartho, Jo Anne
AU - Van Soest, Matthijs
AU - King, David T.
AU - Petruny, Lucille W.
PY - 2012/8
Y1 - 2012/8
N2 - Single crystal (U-Th)/He dating was applied to 24 apatite and 23 zircon grains from the Wetumpka impact structure, Alabama, USA. This small approximately 5-7.6km impact crater was formed in a shallow marine environment, with no known preserved impact melt, thus offering a challenge to common geochronological techniques. A mean (U-Th)/He apatite and zircon age of 84.4±1.4Ma (2σ) was obtained, which is within error of the previously estimated Late Cretaceous impact age of approximately 83.5Ma. In addition, helium diffusion modeling of apatite and zircon grains during fireball/contact, shock metamorphism, and hydrothermal events was undertaken, to show the influence of these individual thermal processes on resetting (U-Th)/He ages in the Wetumpka samples. This study has shown that the (U-Th)/He geochronological technique has real potential for dating impact structures, especially smaller and eroded impact structures that lack impact melt lithologies.
AB - Single crystal (U-Th)/He dating was applied to 24 apatite and 23 zircon grains from the Wetumpka impact structure, Alabama, USA. This small approximately 5-7.6km impact crater was formed in a shallow marine environment, with no known preserved impact melt, thus offering a challenge to common geochronological techniques. A mean (U-Th)/He apatite and zircon age of 84.4±1.4Ma (2σ) was obtained, which is within error of the previously estimated Late Cretaceous impact age of approximately 83.5Ma. In addition, helium diffusion modeling of apatite and zircon grains during fireball/contact, shock metamorphism, and hydrothermal events was undertaken, to show the influence of these individual thermal processes on resetting (U-Th)/He ages in the Wetumpka samples. This study has shown that the (U-Th)/He geochronological technique has real potential for dating impact structures, especially smaller and eroded impact structures that lack impact melt lithologies.
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U2 - 10.1111/j.1945-5100.2012.01381.x
DO - 10.1111/j.1945-5100.2012.01381.x
M3 - Article
AN - SCOPUS:84865290328
SN - 1086-9379
VL - 47
SP - 1243
EP - 1255
JO - Meteoritics and Planetary Science
JF - Meteoritics and Planetary Science
IS - 8
ER -