Primary versus diagenetic isotope signals in Pseudorthoceras sp. from the Buckhorn Asphalt Quarry (mid-Pennsylvanian, Oklahoma) - a detailed study of cameral deposits

Conference contribution
(Abstract of a poster)


Publication Details

Author(s): Seuß B, Titschack J, Nützel A
Publication year: 2010
Language: English


Abstract

Oxygen and carbon stable isotope studies of well-preserved fossils
present an important data source for palaeoclimatic studies. Commonly,
the older the fossils, the less good they are preserved. The Buckhorn
Asphalt Quarry Lagerstätte from the mid-Pennsylvanian of Oklahoma is one
of the few Palaeozoic examples, where original (metastable) shell
material, such as aragonite and high magnesium calcite (HMC) is found,
due to their early post-mortal hydrocarbon impregnation. The Buckhorn
Asphalt Quarry is characterised by fossiliferous sediments soaked with
hydrocarbons, which commonly prevented diagenesis. This study presents
microstructural, mineralogical and stable isotope data from
Pseudorthoceras sp. (two chambers with their cameral deposits).
Therefore data from thin section analysis, scanning electron microscope
(SEM) combined with an energy disperse x-ray (EDX), and x-ray
diffraction (XRD) with a general area detection diffraction system
(GADDS) analysis were combined. XRD-GADDS is a relatively new method to
investigate the shells mineralogy and allows the non-destructive,
site-specific identification of mineral phases.
Altogether seven microstructures were differed in the sections drilled
for isotope dating. These could be divided into two primary
mineralogies, aragonite and HMC. We don’t have any knowledge of cameral
deposits with a HMC mineralogy or found any evidence of this in
literature. The only partially unaltered preserved microstructure is the
nacre of the septum. All other microstructures exhibit a partial or
complete alteration to low magnesium calcite (LMC), or in case of the
primary HMC to LMC and dolomite. According to the isotope signature the
diagenesis took place most likely in the meteoric environment. The
partial diagenesis results in isotope values, which plot along a linear
trend between the two end-members. This linear trend could easily be
misinterpreted as kinetic vital effect, if no sorrow phase control was
performed. The isotopic signal of the primary nacre of the septum
suggest a normal marine environment for these nektonic molluscs, with
tropical temperatures of 14°C to 15°C (δ18Oseawater 1.5 ‰, a typical
value for modern tropical marginal seas).


FAU Authors / FAU Editors

Seuß, Barbara Dr.
Lehrstuhl für Paläoumwelt


External institutions with authors

Ludwig-Maximilians-Universität (LMU)
Universität Bremen


How to cite

APA:
Seuß, B., Titschack, J., & Nützel, A. (2010). Primary versus diagenetic isotope signals in Pseudorthoceras sp. from the Buckhorn Asphalt Quarry (mid-Pennsylvanian, Oklahoma) - a detailed study of cameral deposits. Poster presentation at Annual Meeting of the Paläontologische Gesellschaft, München.

MLA:
Seuß, Barbara, Jürgen Titschack, and Alexander Nützel. "Primary versus diagenetic isotope signals in Pseudorthoceras sp. from the Buckhorn Asphalt Quarry (mid-Pennsylvanian, Oklahoma) - a detailed study of cameral deposits." Presented at Annual Meeting of the Paläontologische Gesellschaft, München 2010.

BibTeX: 

Last updated on 2018-06-12 at 09:23