Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Dinosaur-bearing hyperconcentrated flows of Cretaceous Arctic Alaska; recurring catastrophic event beds on a distal paleopolar coastal plain

Peter P. Flaig, Anthony R. Fiorillo and Paul J. McCarthy
Dinosaur-bearing hyperconcentrated flows of Cretaceous Arctic Alaska; recurring catastrophic event beds on a distal paleopolar coastal plain
Palaios (November 2014) 29 (11): 594-611

Abstract

The Cretaceous coastal plain of Arctic Alaska contains the richest concentration of high-latitude dinosaurs on Earth. Three bonebeds (Liscomb, Byers, Sling Point) are found in paleopolar (82 degrees -85 degrees N) coastal-plain deposits of the Prince Creek Formation on Alaska's North Slope. 40Ar/39Ar analysis of a tuff below the oldest bonebed (Sling Point) returned an age of 69.2+ or -0.5 Ma indicating a maximum early Maastrichtian age for these bonebeds. Bonebeds are overwhelmingly dominated by partially articulated to associated late-stage juvenile Edmontosaurus sp. Bone is rarely found in channels; instead high-density accumulations are preserved on floodplains in laterally extensive, muddy alluvium. Bone size grading is vertically nonuniform and most bones are in hydraulic disequilibrium with the surrounding clay-rich matrix. Bones exhibit little evidence of rounding, weathering, predation, or trampling, suggesting short-distance transport and rapid burial. Because these bonebeds are unlike typical debris-flow or streamflow deposits, the mechanism for bonebed emplacement remained poorly understood. All bonebeds contain a current-rippled siltstone containing the largest bone overlain by a distinctive mudstone encasing smaller bones, bone fragments, and subparallel-aligned plant fragments that appear "frozen in flow" within the muddy matrix. We recognize that these bonebeds exhibit a recurring facies pairing and bipartite division of flow consistent with deposition by fine-grained viscous hyperconcentrated flows. We suggest that exceptional discharge events entrained mud and ash stored on point bars and floodplains, increasing suspended-sediment concentrations in rivers and generating erosive hyperconcentrated flows that transported the remains of scores of juvenile dinosaurs onto floodplains adjacent to distributary channels.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 29
Serial Issue: 11
Title: Dinosaur-bearing hyperconcentrated flows of Cretaceous Arctic Alaska; recurring catastrophic event beds on a distal paleopolar coastal plain
Affiliation: University of Texas at Austin, Bureau of Economic Geology, Austin, TX, United States
Pages: 594-611
Published: 201411
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 133
Accession Number: 2015-016342
Categories: Vertebrate paleontologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: NSF grants OPP-425636 and OPP-424594
Illustration Description: illus. incl. sect., strat. cols., 2 tables, sketch map
N70°00'00" - N70°00'00", W151°30'00" - W151°30'00"
Secondary Affiliation: Perot Museum of Nature and Science, USA, United StatesUniversity of Alaska at Fairbanks, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201508
Close Modal

or Create an Account

Close Modal
Close Modal