Modeling position specific carbon isotopologue fractionation of thermogenic propane and precursors

Abstract

<p>Position specific isotope analysis (PSIA) of thermogenic propane allows to track carbon isotopic compositions at different molecular positions, and thus providing new evidence to investigate propane��s origin, fate, and mechanisms of formation. However, the link between observed ��<sup>13</sup>C PSIA signals of propane and carbon isotopologue signatures of precursors in source organics still remains unclear, and understanding the underlying mechanisms requires a more sophisticated model. Here we developed a mathematical framework to simulate position specific carbon isotopologues of propane and its precursors based on mechanistic understanding of thermogenic propane��s bond-cleavage pathways. Besides, our model also allows integrates multiple signals including temperature, and isotopic characteristics of source compounds. Our model is validated by precisely reproducing propane��s PSIA experimental data obtained during cracking of different kerogens, and also correctly quantified the initial carbon isotopic signatures and the initial fraction of the different precursors in the source materials. Our model allows to include more complex reaction mechanisms to elucidate and unknown reaction pathways, and could also guide and optimize future experimental studies to test different hypothesis.</p>