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Sedimentary facies and trilobite biofacies along an Ordovician shelf to basin gradient, Viola Group, south-central Oklahoma

Lisa Amati and Stephen R. Westrop
Sedimentary facies and trilobite biofacies along an Ordovician shelf to basin gradient, Viola Group, south-central Oklahoma
Palaios (December 2006) 21 (6): 516-529

Abstract

The Upper Ordovician Viola Group of south-central Oklahoma records deposition on a carbonate ramp that extended from platformal settings to a basin within the Southern Oklahoma aulacogen. Lithofacies analysis allows identification of inner, mid- and outer-ramp environments in the Viola Springs Formation, each of which hosted a distinct trilobite biofacies. There is a sharp break in both composition and species diversity of biofacies between the outer ramp within the aulacogen and shallower environments. The outer-ramp Cryptolithine Biofacies is characterized by low species diversity, whereas both the midramp Thaleops Biofacies and the inner-ramp Bumastoides Biofacies contain up to four times as many trilobite species and rare cryptolithines. Comparisons with Cambrian and older Ordovician shelf-to-basin trilobite distributions suggest that the pattern recorded in the Viola Springs is depth related. The overlying Welling Formation includes two biofacies in inner- to midramp environments, with the faunas of the aulacogen being less diverse than those of the platform. The high trilobite species diversity in shallow water environments of the Viola Group supports a dilution model for community reorganization during the Ordovician.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 21
Serial Issue: 6
Title: Sedimentary facies and trilobite biofacies along an Ordovician shelf to basin gradient, Viola Group, south-central Oklahoma
Affiliation: University of Oklahoma, School of Geology and Geophysics, Norman, OK, United States
Pages: 516-529
Published: 20061201
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 79
Accession Number: 2007-010790
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., geol. sketch map
N34°04'00" - N34°57'00", W97°32'60" - W96°22'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200707
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