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Extreme heat in the Early Ordovician

Page C. Quinton, Laura Speir, James Miller, Raymond Ethington and Kenneth G. Macleod
Extreme heat in the Early Ordovician
Palaios (August 2018) 33 (8): 353-360


Global cooling and the establishment of a moderate climate in the Middle Ordovician has been invoked as the primary driver of the tenfold increase in marine biodiversity that characterized the Great Ordovician Biodiversification Event (GOBE). Arguments suggesting that climate change played a significant role in biodiversification purport that the Early Ordovician was dominated by warm (possibly even extremely warm) temperatures. In this scenario, biodiversification occurred only after sea surface temperatures approached the range observed in modern tropical settings. Temperature constraints for the Early Ordovician, however, are limited in number and documentation of short-term climatic trends is lacking. This study aims to begin to address these shortcomings by presenting a new high-resolution phosphate oxygen isotope record of species-specific and mixed conodont assemblages from the Lange Ranch section of central Texas. We document consistently low delta (super 18) O values indicating that the Early Ordovician was characterized by extreme warmth. In addition, variations observed in delta (super 18) O values through the section are consistent with a short-lived (< 4 m.y.) warming event and/or oceanographic shift leading to a decrease in the delta (super 18) O value of local seawater. All new data generated for this study are consistent with very warm temperatures during the Early Ordovician, an important starting condition in arguments that climate played an important role in Middle Ordovician biodiversification, but variation found also demonstrates the need for high resolution studies to constrain conditions on time scales relevant to evolutionary diversification.

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 33
Serial Issue: 8
Title: Extreme heat in the Early Ordovician
Affiliation: State University of New York at Potsdam, Department of Geology, Potsdam, NY, United States
Pages: 353-360
Published: 201808
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 56
Accession Number: 2018-082092
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: NSF Grant EAR-1323444
Illustration Description: illus. incl. strat. col., 1 table, geol. sketch map
N30°26'60" - N30°26'60", W99°07'00" - W99°07'00"
Secondary Affiliation: University of Missouri at Columbia, USA, United StatesMissouri State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, 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: 2018
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