Ecosystem perturbation caused by a small Late Cretaceous marine impact, Gulf Coastal Plain, USA
Published:January 01, 2007
David T. King, Jr., Lucille W. Petruny, Thornton L. Neathery, 2007. "Ecosystem perturbation caused by a small Late Cretaceous marine impact, Gulf Coastal Plain, USA", Large Ecosystem Perturbations: Causes and Consequences, Simonetta Monechi, Rodolfo Coccioni, Michael Rampino
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The Wetumpka impact event, ca. 83.5 Ma in shallow waters of the northern Gulf of Mexico, caused minor ecosystem perturbations because of the physical effects of a 2.6-gigaton-equivalent impact detonation. The impact event and its consequences had relatively minor, but notable, paleobiologic effects (i.e., preservational effects, biostratigraphic effects, and impact-succession effects). The impact structure served as a local reservoir for an impact-entombed fossil record in two main ways. First, coarse to fine fragments of terrestrial vegetation, probably derived from the adjacent tropical forest, were swept up and incorporated into Wetumpka washback- and surgeback-deposited breccias and sands. Second, intact blocks of target sedimentary units, which contain an internal fossil component of their own, are part of the slump and fallback debris that partially fills the Wetumpka impact structure. Some of these target sedimentary rock blocks include updip sedimentary facies of these formations that no longer exist in outcrops anywhere in the region. In yet another paleoecologic effect, the Wetumpka impact crater apparently functioned as a minor terrestrial (island) ecosystem embedded within the shelfal marine realm for an unknown length of time. As one might expect from the relatively small size of this structure, there is no apparent regional or global biotic extinction event associated with this local catastrophe.