Plant microfossil record of the terminal cretaceous event in the western United States and Canada

Geological Society of America Special Papers
By:  and 



Shortly after the introduction of the extraterrestrial-impact hypothesis of the terminal Cretaceous event (TCE), plant microfossils, which had been used to locate the Cretaceous/Tertiary (K/T) boundary in nonmarine rocks, became critical to its precise identification; they continue to serve in this capacity. The K/T boundary in nonmarine rocks from New Mexico to Alberta is identified by the coincidence of a palynological extinction horizon and an iridium abundance anomaly. Plant microfossils provide evidence of the effects of the TCE and place constraints on theories of its cause. Changes in plant microfossil assemblages within intervals spanning the K/T boundary are evidence of abrupt and permanent changes in terrestrial, floras that were a consequence of the TCE; these changes are essentially independent of lithofacies. Extinction levels varied among major groups of plants (angiosperms, gymnosperms, and pteridophytes), but simultaneously affected different plant communities throughout the region. The abrupt nature of the extinction across western North America is consistent with the impact hypothesis; it is inconsistent with progressive change in paleoclimate possibly being the cause of the terminal Cretaceous extinctions. By causing the extinction of a significant portion of the Late Cretaceous flora of the region, the TCE influenced the development of the modern flora, but its effects appear to have been concentrated in western North America.

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Publication type Article
Publication Subtype Journal Article
Title Plant microfossil record of the terminal cretaceous event in the western United States and Canada
Series title Geological Society of America Special Papers
DOI 10.1130/SPE247-p445
Volume 247
Year Published 1990
Language English
Publisher Geological Society of America
Description 11 p.
First page 445
Last page 455
Country United States, Canada
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