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Constraints on Pennsylvanian glacioeustatic sea-level changes using oxygen isotopes of conodont apatite

Michael M. Joachimski, Peter H. von Bitter and Werner Buggisch
Constraints on Pennsylvanian glacioeustatic sea-level changes using oxygen isotopes of conodont apatite
Geology (Boulder) (April 2006) 34 (4): 277-280


Conodonts from U.S. Midcontinent cyclothems were studied for oxygen isotopes in order to constrain Pennsylvanian glacioeustatic sea-level fluctuations. Pennsylvanian deposits of the Midcontinent United States are composed of cyclic alternations of thin transgressive limestones, offshore gray to black phosphatic shales, and thick regressive limestones, a sequence that is underlain and overlain by nearshore to terrestrial shales with paleosols and coal beds. Glacioeustatic sea-level fluctuations are considered the primary cause for the formation of these cyclothems. Oxygen isotope analyses of conodont apatite from the black (20.1+ or -0.5 ppm, Vienna standard mean ocean water [VSMOW]) and gray shale units (20.5+ or -0.5 ppm, VSMOW) show lowest average delta (super 18) O values, whereas conodont elements from the regressive (21.0+ or -0.3 ppm, VSMOW) and transgressive limestone units (21.1+ or -0.6 ppm, VSMOW) are enriched in (super 18) O. The maximum change in delta (super 18) O of conodonts from the black shale and carbonate units from individual cyclothems is 1.7 ppm. The 1.7 ppm difference in delta (super 18) O compares relatively well to Pleistocene interglacial-glacial changes in delta (super 18) O of equatorial surface-dwelling foraminifers and suggests that Pennsylvanian glacioeustatic sea-level changes may have been of comparable amplitude. However, since the Pennsylvanian glacial maxima are represented by terrestrial sediments and are not documented in the conodont oxygen isotope record, Pennsylvanian glacioeustatic sea-level changes were probably larger than the 120 m fluctuations recorded for the Pleistocene glaciations.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 34
Serial Issue: 4
Title: Constraints on Pennsylvanian glacioeustatic sea-level changes using oxygen isotopes of conodont apatite
Affiliation: University of Erlangen, Institute of Geology and Mineralogy, Erlangen, Federal Republic of Germany
Pages: 277-280
Published: 200604
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 26
Accession Number: 2006-035340
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2006058
Illustration Description: illus. incl. 1 table
N40°25'00" - N43°30'00", W96°34'60" - W90°10'00"
N37°00'00" - N40°00'00", W102°00'00" - W94°34'60"
N36°00'00" - N40°34'60", W95°45'00" - W89°04'60"
N40°00'00" - N43°00'00", W104°04'60" - W95°19'60"
N33°34'60" - N37°00'00", W103°00'00" - W94°25'00"
Secondary Affiliation: Royal Ontario Museum, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200619
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