Near-K/T age of clastic deposits from Texas to Brazil: impact,volcanism and/or sea-level lowstand? |
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Authors: | Gerta Keller Wolfgang Stinnesbeck |
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Institution: | Department of Geological and Geophysical Sciences, Princeton University, Princeton, NJ 08544;Facultad de Ciencias de la Tierra, Universidad Autónoma de Nuevo, Leon, 67700 Linares, NL Mexico |
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Abstract: | Near-K/T boundary clastic deposits from Texas, Mexico, Haiti, Guatemala and Brazil, often described as impact-generated tsunami deposits, are stratigraphically below well-defined K/T boundary horizons and appear not to be causally related to the K/T boundary event. Stratigraphic evidence indicates that their deposition began during the last 170–200 kyr of the Maastrichtian, coincident with a major eustatic sea-level lowstand that lowered sea level by as much as 70–100 m. Clastic deposition ended a few tens of thousands of years before the K/T boundary during a rapidly rising sea level. The presence of glass in clastic deposits in Haiti, northeastern Mexico and Yucatan suggests that the sea-level lowstand coincided with a time of major volcanism or pre-K/T boundary bolide impact. |
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