scholarly journals Sedimentary process control on carbon isotope composition of sedimentary organic matter in an ancient shallow‐water shelf succession

2012 ◽  
Vol 13 (11) ◽  
Author(s):  
S. J. Davies ◽  
M. J. Leng ◽  
J. H. S. Macquaker ◽  
K. Hawkins
Keyword(s):  
Organic Matter ◽  
Process Control ◽  
Shallow Water ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Sedimentary Organic Matter ◽  
Sedimentary Process

scholarly journals Preliminary results of studying the carbon isotope composition of conodont elements at the border of Devonian and Carboniferous periods (Kamenka river sections, Pechora carbonate platform)

LITOSFERA ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 829-841
Author(s):  
A. V. Zhuravlev ◽  
I. V. Smoleva
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Isotopic Composition ◽  
Shallow Water ◽  
Carbon Isotope ◽  
Stable Carbon Isotopes ◽  
Carbonate Platform ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Oligotrophic Ecosystem

Research subject. Changes in the trophic structure of shallow-water pelagic ecosystems at the Devonian/Carboniferous border were investigated by studying the carbon isotope composition of conodont organic matter.Materials and methods. Two Devonian-Carboniferous shallow-water clayey-carbonate sections located in the southern part of the Pechora-Kozhva Uplift (Pechora Plate) were analysed. The Devonian-Carboniferous boundary was detected by the first occurrences of Siphonodella sulcata, S. semichatovae and Patrognathus crassus, as well as by the last occurrence of Pseudopolygnathus graulichi. The carbon isotope composition was investigated both in whole-rock carbonate samples and the conodont organic matter of two dominant species (Polygnathus parapetus and P. communis communis).Results. The distribution of stable carbon isotopes in the organic matter of conodont elements accompanied by the data on carbonate isotope composition allowed us to suggest changes in the food composition of the dominant taxa during the Late Famennian-Early Tournaisian transition. It was assumed that the latest Famennian representatives of Polygnathus parapetus and P. communis communis consumed largely phyto- and zooplankton, which is characterized by a light isotopic composition of organic carbon. The nutrition based on phyto- and zooplankton with a heavier isotopic composition of organic carbon was suggested for the early Tournaisian representatives of these species.Conclusions. The discovered variations in the carbon isotope composition of conodont organic matter in shallow-water facies may correspond to the change from the eutrophic pelagic ecosystem to the oligotrophic ecosystem, and/or global perturbation of the carbon cycle due to climatic changes. Since the available data is limited to two geological sections, it is impossible to unambiguously interpret the scale (local, regional, global) of these variations and their correlation potential.

scholarly journals Comparison of organic geochemical and palynofacies methods: Example from the Upper Triassic Gassum Formation in Denmark

1991 ◽  
Vol 38 ◽  
pp. 267-277
Author(s):  
Bjørn Buchardt ◽  
Marianne Vasard Nielsen
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Carbon Isotope Composition ◽  
Preparation Methods ◽  
Rock Samples ◽  
Deep Well ◽  
Amorphous Organic Matter

Copenhagen, February 19th, 1991. Disseminated organic matter from the · Upper Triassic to Lower Jurassic Gassum Formation in the Gassum-1 deep well has been analyzed by palynological and organic geochemical methods. Tue paper compares the effects of the different preparation methods on the organic matter. The kerogen isolation process (demineralisation by HF) is found to cause major changes in the Rock-Eva! parameters, but not in carbon isotope composition of organic matter. Tm.,- and HI-values determined from kerogen concentrates are more consistent with the palynofacies data than those determined from whole rock samples. The differences are ascribed to analytical problems when dealing with low-TOC whole rock samples. Palynofa­cies data obtained from unfiltered and filtered kerogen concentrates demonstrate a variable loss of amorphous organic matter during filtration ( up to 1()()%). Other palynomorph distributions are not seriously affected by filtration. The loss in amorphous organic matter has no influence on the Rock-Eva! data and carbon isotope composition. Comparison of polynofacies and carbon isotope data identifies three organic matter sources with characteristic isotopic composition.

The carbon isotope composition of organic matter occluded in iron nodules

1994 ◽  
Vol 114 (3-4) ◽  
pp. 269-279 ◽  
Author(s):  
M.I. Bird ◽  
J. Quade ◽  
A.R. Chivas ◽  
L.K. Fifield ◽  
G.L. Allan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Carbon Isotope Composition
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