Stable-isotope stratigraphy of brachiopods from Pennsylvanian shales in Texas

Research Article| July 01, 1991 Stable-isotope stratigraphy of brachiopods from Pennsylvanian shales in Texas ETHAN L. GROSSMAN; ETHAN L. GROSSMAN 1Department of Geology, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar CHUANLUN ZHANG; CHUANLUN ZHANG 1Department of Geology, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar THOMAS E. YANCEY THOMAS E. YANCEY 1Department of Geology, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar Author and Article Information ETHAN L. GROSSMAN 1Department of Geology, Texas A&M University, College Station, Texas 77843 CHUANLUN ZHANG 1Department of Geology, Texas A&M University, College Station, Texas 77843 THOMAS E. YANCEY 1Department of Geology, Texas A&M University, College Station, Texas 77843 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1991) 103 (7): 953–965. https://doi.org/10.1130/0016-7606(1991)103<0953:SISOBF>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ETHAN L. GROSSMAN, CHUANLUN ZHANG, THOMAS E. YANCEY; Stable-isotope stratigraphy of brachiopods from Pennsylvanian shales in Texas. GSA Bulletin 1991;; 103 (7): 953–965. doi: https://doi.org/10.1130/0016-7606(1991)103<0953:SISOBF>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Stable-isotope stratigraphies have been generated for brachiopods from five Late Pennsylvanian sections (upper Winchell cycle, Finis shale, Colony Creek shale, Necessity cycle, and Wayland shale) in north-central Texas to examine the relationship between isotopic composition, paleoenvironment, and sea-level change. Nonluminscent calcite from more than 300 specimens of 4 species of brachiopod (Composita subtilita, Crurithyris planoconvexa, Eridmatus texana, Neospirifer cameratus) was analyzed. Sedimentological and paleontological data are used as evidence for paleoenvironmental change.Higher δ18O values of brachiopod shells occur in intervals of greatest paleodepth as indicated by fossil content and lithology. These higher δ18O values reflect a decrease in bottom temperature with increased water depth. Normalized for paleodepth, the δ18O values of the brachiopods are similar in all of the units except the Wayland shale, for which they are ∼0.5‰ higher. This suggests either cooler temperatures or greater continental ice volume during the time of Wayland deposition.Brachiopod δ13C values do not correlate with paleodepth. The δ13C values of Composita are consistently higher than those of Crurithyris and Eridmatus. Composita δ13C values are similar in the upper Winchell cycle, Necessity cycle, and Wayland shale, averaging 4.8‰ to 4.9‰. In contrast, Crurithyris δ13C values range from 2.5‰ in the Necessity cycle to 4.4‰ in the Wayland shale; Eridmatus values are also lowest in the Necessity cycle (3.4‰) and greatest in the Wayland shale (3.9‰). These differences between species do not correlate with susceptibility to diagenesis and appear to reflect a pore-water influence on semi-infaunal (Crurithyris) forms. The δ13C values of Composita shells suggest that the Late Pennsylvanian ocean off eastern Laurussia was enriched in 13C by about 1‰ relative to the ocean off western Laurussia. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.