Examinando por Autor "King, David T."

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Acceso Abierto
Assessing event magnitude and target water depth for marine-target impacts: Ocean resurge deposits in the Chicxulub M0077A drill core compared
(Elsevier BV, 2021-06-15) Ormö, Jens; Gulick, S. P. S.; Whalen, M. T.; King, David T.; Sturkell, Erik; Morgan, Joanna; Polish National Science Centre; Gordon and Betty Moore Foundation (GBMF)
The rim wall of water formed from even a modestly-sized marine impact may be kilometers in height. Although modeling has shown that this wave swiftly breaks and relatively rapidly loses energy during outwards travel from the impact site, the portion of the rim wall that collapses inwards may generate a resurge flow with tremendous transport energy. Here we compare the deposits generated by this ocean resurge inside one of the largest marine-target craters on Earth, the 200-km wide Chicxulub crater, Yucatán Peninsula, México, with resurge deposits (breccias) in eight drill cores from five other marine-target craters in Sweden and the United States. Examination of the wide range of cored locations within the craters, and target water depths (H) relative to modeled projectile diameters (d) reveal a high correlation between location, average clast frequency (), and from which any of the four variables can be obtained. The relationship shown here may provide an important tool for diagnosing marine impact cratering processes where there is limited understanding of crater size and/or paleobathymetry.
Restringido
The Decorah impact structure (Iowa, USA): A case study for assessing target water depth and paleoenvironment for past marine target impacts in present-day non-marine locations
(Geological Society of America, 2025-12) Ormö, Jens; Sturkell, Erik; King, David T.
Reconstructing paleoenvironments—particularly aquatic ones—is essential for identifying potential habitats for life, both on early Earth and early Mars. Impact craters often serve as effective sediment traps that are relatively shielded from erosion. In aquatic settings—most commonly in shallow marine environments—where seafloor craters can form, the return flow of water during the early stages of crater modification can produce distinctive resurge deposits. Analyses of such deposits from drill cores at various marine-target impact structures, including the Decorah impact structure (Iowa, USA) examined in this study, reveal a direct correlation between average clast frequency per meter, impact event magnitude (i.e., projectile diameter), and the depth of the target water. If two of these parameters are known, the third can be inferred. In this study, we analyzed two drill cores obtained from the interior of the Decorah impact structure to gain insights into the paleoenvironment at the time of impact. Applying the aforementioned relationships yields an estimated target water depth of 40–90 m, thereby situating the Decorah impact structure paleoenvironment within a defined range of the ancient marine realm.