The second edition of The Biomarker Guide is a fully updated and expanded version of this essential reference. Now in two volumes, it provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes. Biomarkers and Isotopes in the Environment and Human History details the origins of biomarkers and introduces basic chemical principles relevant to their study. It discusses analytical techniques, and applications of biomarkers to environmental and archaeological problems. The Biomarker Guide is an invaluable resource for geologists, petroleum geochemists, biogeochemists, environmental scientists and archaeologists.
A combination of solid-state 13C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption
near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species
and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic
matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data
shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between
the Rock−Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice
parameters are derived from solid-state 13C NMR analysis. As expected, the amount of aromatic carbon, measured
by both 13C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and
Rock−Eval T
max, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter
type follows a different relationship. The average aliphatic carbon chain length (Cn‘) decreases with an increasing
amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons
with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases
with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12
to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted.
There is basic agreement between XPS and 13C NMR results for the amount and speciation of organic oxygen.
XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl−carboxyl
species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen
and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur
seen in the kerogens. XPS and S-XANES results indicate that the relative level of aromatic sulfur increases
with an increasing amount of aromatic carbon for all kerogens. XPS show that the majority of nitrogen exists
as pyrrolic forms in comparable relative abundances in all kerogens studied. The direct characterization results
using X-ray and NMR methods for nitrogen, sulfur, oxygen, and carbon chemical structures provide a basis
for developing both specific and general average chemical structural models for different organic matter type
kerogens.
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