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GEOREF RECORD

Paleocene and latest Cretaceous mammal ages, biozones, magnetozones, rates of sedimentation, and evolution

Robert E. Sloan
Paleocene and latest Cretaceous mammal ages, biozones, magnetozones, rates of sedimentation, and evolution (in The Cretaceous-Tertiary boundary in the San Juan and Raton basins, New Mexico and Colorado, James E. Fassett (editor) and J. Keith Rigby (editor))
Special Paper - Geological Society of America (1987) 209: 165-200

Abstract

North American Paleocene land mammal ages are the Mantuan, Puercan, Torrejonian, Tiffanian, and Clarkforkian. These ages (and associate stages) are subdivided into 16 zones or subzones, varying in duration from 0.1 to 2.9 m.y., defined by widespread species. Although gross evolutionary changes during the first four of these ages are about equal, their durations are very unequal. As defined by magnetostratigraphy and fossil occurrence, the Mantuan is about 0.2 m.y., the Puercan about 1.1 m.y., the Torrejonian about 3.1 m.y., the Tiffanian about 6.1 m.y., and the Paleocene part of the Clarkforkian about 1.3 m.y. in duration. Puercan encompasses normal magnetozone 29, Torrejonian zones 28 and 27, and the Tiffanian-Clarkforkian boundary falls in zone 25. The type Rio Chico Formation of Patagonia is of mid-Tiffanian to Clarkforkian age. Problems in the identification of magnetozones in the San Juan Basin have arisen because an unconformity is present between the Kirtland Shale and the Ojo Alamo Sandstone, and for some years an extra normal chron was falsely identified. When this hiatus is taken into account, marine and terrestrial fossil correlations agree with magnetozone correlations throughout Upper Cretaceous and Paleocene rocks. The Danian stage in marine rocks in North Dakota is equivalent to Mantuan through early Tiffanian; the Thanetian is exactly equivalent to mid-Tiffanian to early Clarkforkian. The rate of Paleocene sedimentation in the major basins of North America does not depart from linearity much more than the contemporary rate of seafloor spreading. Terrestrial rates of sedimentation vary from a peak of 568 bubnoffs (b) (meters per million years) for the Hoback Formation at the Rocky Mountain front to 99 b in the San Juan Basin and 15 b in the Black Peaks Formation in Texas, compared to 2.7 b at Gubbio, Italy. Sedimentation rates along a transect through the Bighorn, Powder River, and Williston basins follow the equation Y = 200X (super -0.25) , where Y is the sedimentation rate in bubnoffs and X is the radial distance in kilometers from the Absaroka thrust. Absolute taxonomic and morphologic rates of evolution of the most rapidly evolving mammals during the Bugcreekian-Mantuan interval across the Cretaceous-Paleocene boundary peak at 5 genera per m.y. and 3.85 darwins (a rate of measurement defined in the text), the fastest rates known in the fossil record, and decline exponentially to more normal rates of 1 species per m.y. and 0.5 darwins by the Tiffanian. Range charts of 299 species of ungulates, primates, and multituberculates permit ready identification of zones. Seven new species of multituberculates are described, and shape and metrical properties of latest Cretaceous-Paleocene neoplagiaulacid multituberculates are summarized for ease in identification.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 209
Title: Paleocene and latest Cretaceous mammal ages, biozones, magnetozones, rates of sedimentation, and evolution
Title: The Cretaceous-Tertiary boundary in the San Juan and Raton basins, New Mexico and Colorado
Author(s): Sloan, Robert E.
Author(s): Fassett, James E.editor
Author(s): Rigby, J. Keith, Jr.editor
Affiliation: Univ. Minn., Dep. Geol. and Geophys., Minneapolis, MN, United States
Affiliation: U. S. Geol. Surv., Reston, VA, United States
Pages: 165-200
Published: 1987
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Meeting name: Geological Society of America, Rocky Mountain and Cordilleran sections, joint meeting ; The Cretaceous-Tertiary boundary in the San Juan and Raton basins, New Mexico and Colorado
Meeting location: Salt Lake City, UT, USA, United States
Meeting date: 198305May 1983
References: 175
Accession Number: 1987-041947
Categories: StratigraphyVertebrate paleontology
Document Type: Serial Conference document Map
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, sketch map
Map Scale: 1:250,000
Map Type: geologic map
N25°45'00" - N36°30'00", W106°30'00" - W93°30'00"
N32°00'00" - N65°00'00", W155°00'00" - W103°00'00"
N45°55'00" - N49°00'00", W104°04'60" - W96°34'60"
N31°30'00" - N37°00'00", W109°04'60" - W103°00'00"
N37°00'00" - N41°00'00", W109°00'00" - W102°00'00"
N29°00'00" - N56°00'00", W115°00'00" - W97°00'00"
Secondary Affiliation: Univ. Notre Dame, Dep. Earth Sci., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Bibliography of Fossil Vertebrates, Society of Vertebrate Paleontology, Berkeley, CA, United States
Update Code: 1987
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