The isotopic structures of geological organic compounds
John M. Eiler, Matthieu Clog, Michael Lawson, Max Lloyd, Alison Piasecki, Camilo Ponton, Hao Xie, 2018. "The isotopic structures of geological organic compounds", From Source to Seep: Geochemical Applications in Hydrocarbon Systems, M. Lawson, M.J. Formolo, J.M. Eiler
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Organic compounds are ubiquitous in the Earth’s surface, sediments and many rocks, and preserve records of geological, geochemical and biological history; they are also critical natural resources and major environmental pollutants. The naturally occurring stable isotopes of volatile elements (D, 13C, 15N, 17,18O, 33,34,36S) provide one way of studying the origin, evolution and migration of geological organic compounds. The study of bulk stable isotope compositions (i.e. averaged across all possible molecular isotopic forms) is well established and widely practised, but frequently results in non-unique interpretations. Increasingly, researchers are reading the organic isotopic record with greater depth and specificity by characterizing stable isotope ‘structures’ – the proportions of site-specific and multiply substituted isotopologues that contribute to the total rare-isotope inventory of each compound. Most of the technologies for measuring stable isotope structures of organic molecules have been only recently developed and to date have been applied only in an exploratory way. Nevertheless, recent advances have demonstrated that molecular isotopic structures provide distinctive records of biosynthetic origins, conditions and mechanisms of chemical transformation during burial, and forensic fingerprints of exceptional specificity. This paper provides a review of this young field, which is organized to follow the evolution of molecular isotopic structure from biosynthesis, through diagenesis, catagenesis and metamorphism.
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Hydrocarbon systems, by nature, are a complex interplay of elements that must be spatially and temporally aligned to result in the generation and preservation of subsurface hydrocarbon accumulations. To meet the increasing challenges of discovering hydrocarbon resources, it is essential that we advance our understanding of these systems through new geochemical approaches and analytical developments. Such development requires that academic- and industry-led research efforts converge in ways that are unique to the geosciences.
The aim of this volume is to bring together a multidisciplinary geochemical community from industry and academia working in hydrocarbon systems to publish recent advances and state-of-the-art approaches to resolve the many remaining questions in hydrocarbon systems analysis. From Source to Seep presents geochemical and isotopic studies that are grouped into three themes: (1) source-rock identification and the temperature/timing of hydrocarbon generation; (2) mechanisms and time-scales associated with hydrocarbon migration, trapping, storage and alteration; and (3) the impact of fluid flow on reservoir properties.