Late Paleozoic environments : carbon and oxygen isotope records and elemental concentrations of brachiopod shells /
More than 500 fossil brachiopod shells from West Spitsbergen, North America, and the Russian Platform were analyzed for carbon and oxygen isotopes to unravel Late Paleozoic environments. This study strongly suggests that the >9% isotopic shifts reported in Gruszczynski et al. (1989) are diageneti...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739667831&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | More than 500 fossil brachiopod shells from West Spitsbergen, North America, and the Russian Platform were analyzed for carbon and oxygen isotopes to unravel Late Paleozoic environments. This study strongly suggests that the >9% isotopic shifts reported in Gruszczynski et al. (1989) are diagenetic artifacts. However, this study substantiates their Kazanian-Tatarian 13C maximum (7.5%). Within stratigraphic uncertainty, this Late Permian 13C maximum correlates with whole-rock 13C maximum in East Greenland and northwestern Europe and may reflect increasing global storage of organic carbon. Nonluminescent shell 13C values show mid-Carboniferous shifts of 2% and 3% respectively, for North America and the Russian Platform. Within stratigraphic uncertainty, these shifts are accordant to the 3% 13C shift for Europe (Popp et al., 1986a). The 2% shift observed in both the North American and European records was caused by an increased burial rate of organic carbon as suggested by Popp et al. (1986a), whereas the remaining 1% difference between North America and Europe was probably due to changes in ocean circulation associated with the formation of Pangea. The formation of Pangea probably began in the late Chesterian based on the timing of the 13C deviation between the western and eastern Laurussia. We observed 1 to 2% shifts in 18O on time scales of 10 years in Carboniferous North America and the late Carboniferous Russian Platform. The late Carboniferous 18O shift was due to continental ice volume change as supported by geological evidence. The Mississippian 18O shift for North America may be caused the temperature change, excess evaporation, and/or continental ice volume change. Contours of 18O, Mg, Na, and S concentrations parallel growth bands of Neospirifer dunbari reveal a record of 1-1/2 to 2 seasonal cycles. Mg, S, and Na contents varied inversely with 18O. The -1.2%o range in 18O values suggests a seasonal temperature variation of 5 to 6 C. This high seasonality supports climate-model predictions of enhanced continentality in Pangean climate. Detailed oxygen isotope and element concentration profiles across growth bands of brachiopod shells can provide quantitative records of Paleozoic seasonality. |
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| Item Description: | Vita. "Major Subject: Geology". |
| Physical Description: | xiii, 192 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 107-117. |