Late Pennsylvanian seasonality reflected in the 18O and elemental composition of a brachiopod shell

Research Article| July 01, 1994 Late Pennsylvanian seasonality reflected in the 18O and elemental composition of a brachiopod shell Horng-Sheng Mii; Horng-Sheng Mii 1Department of Geology, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar 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 Geology (1994) 22 (7): 661–664. https://doi.org/10.1130/0091-7613(1994)022<0661:LPSRIT>2.3.CO;2 Article history first online: 02 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 Horng-Sheng Mii, Ethan L. Grossman; Late Pennsylvanian seasonality reflected in the 18O and elemental composition of a brachiopod shell. Geology 1994;; 22 (7): 661–664. doi: https://doi.org/10.1130/0091-7613(1994)022<0661:LPSRIT>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 SocietyGeology Search Advanced Search Abstract To evaluate the potential for the study of Late Pennsylvanian seasonality, detailed isotopic and elemental analyses were performed on a single specimen of the brachiopod Neospirifer dunbari. Shell preservation was evaluated by petrographic and cathodoluminescence microscopy. Carbonate powders from 112 spots were collected from the sectioned shell for isotopic analyses, and 369 spots on the complementary thin section were analyzed by electron microprobe for chemical composition. In the nonluminescent part of the shell, Mg/Ca ratios were between 0.001 and 0.012, and Na/Ca and S/Ca ratios ranged from 0.003 to 0.012 and 0.003 to 0.021, respectively. Values of δ18O vary between -2.3‰ and -1.1‰. Contours of 18O, Mg, Na, and S concentrations parallel growth bands and reveal a record of 1½ to 2 cycles. Mg, S, and Na contents varied nversely with δ18O. This trend is opposite to the expected diagenetic trend and is consistent with the temperature dependences of Mg content and δ18O, thus implying preservation of shell chemistry. The ∼1.2‰ range in δ18O values suggests a seasonal temperature variation of 5 to 6 °C (assuming no change in the δ18O of the water). This high seasonality for the tropical epicontinental sea of Kansas supports climate-model predictions of enhanced continentality in Pangean climate. Detailed stable isotope and element concentration profiles across growth bands of brachiopod shells can provide quantitative records of Paleozoic seasonality. 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.