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.
|Original language||English (US)|
|Number of pages||9|
|State||Published - May 1 1996|
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