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GEOREF RECORD

Palynology of the Cretaceous-Tertiary boundary in the northern Rocky Mountain and Mississippi Embayment regions

Robert H. Tschudy
Palynology of the Cretaceous-Tertiary boundary in the northern Rocky Mountain and Mississippi Embayment regions
Special Paper - Geological Society of America (1970) 127: 65-111

Abstract

In both the Rocky Mountain and the Mississippi Embayment regions it is often difficult to distinguish Upper Cretaceous from lower Tertiary rocks on the basis of physical characteristics; the transition can be recognized with relative ease, however, on the basis of abrupt qualitative changes in plant microfossils. Many Cretaceous species vanish and new species appear in the Paleocene. In both regions the Paleocene yields fewer species than does the underlying Cretaceous. A pronounced difference exists between the Late Cretaceous pollen and spore floras of the two regions. The spore-pollen assemblage from the Rocky Mountains is partially characterized by the presence of Aquilapollenites, Proteacidites, Wodehouseia, and an unnamed species of TRICOLPITES: These taxa are not found in the Late Cretaceous of the Mississippi Embayment region. The embayment region yields Rugubivesiculites, an unnamed species of Araucariacites, and several genera belonging to the Normapolles group that are not found in the Rocky Mountain region. The Mississippi Embayment Cretaceous and Paleocene pollen floras show greater similarities to pollen floras from Europe than to those from the northern Rocky Mountains. The Rocky Mountain pollen floras exhibit closer similarities to the Alaskan and Siberian floras. It is suggested that the floral dissimilarity between the Mississippi Embayment and the northern Rocky Mountain regions may be accounted for by the separation of the Rocky Mountain province from the Mississippi Embayment province during Late Cretaceous time by the great north-trending Cretaceous epeiric sea. It is further suggested that the floral changes across the Cretaceous-Tertiary transition may have been caused by slight climatic changes brought about by uplift or by withdrawal of the tempering influence of the epeiric sea.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 127
Title: Palynology of the Cretaceous-Tertiary boundary in the northern Rocky Mountain and Mississippi Embayment regions
Author(s): Tschudy, Robert H.
Pages: 65-111
Published: 1970
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 1971-026555
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. (incl. sketch maps)
N32°00'00" - N65°00'00", W155°00'00" - W103°00'00"
Source Note: No. 127
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1971
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