Reviews in Mineralogy & Geochemistry
Vol. 75 pp. 449-465, 2013
Copyright © Mineralogical Society of America
On the Origins of Deep Hydrocarbons
Mark A. Sephton, Robert M. Hazen
INTRODUCTION
Deep deposits of hydrocarbons, including varied reservoirs of petroleum and natural gas,
represent the most economically important component of the deep carbon cycle. Yet despite
their intensive study and exploitation for more than a century, details of the origins of some
deep hydrocarbons remain a matter of vocal debate in some scientific circles. This long and
continuing history of controversy may surprise some readers, for the biogenic origins of “fossil
fuels”—a principle buttressed by a vast primary scientific literature and established as textbook
orthodoxy in North America and many other parts of the world—might appear to be settled fact.
Nevertheless, conventional wisdom continues to be challenged by some scientists.
The principal objectives of this chapter are: (1) to review the overwhelming evidence
for the biogenic origins of most known deep hydrocarbon reservoirs; (2) to present equally
persuasive experimental, theoretical, and field evidence, which indicates that components of
some deep hydrocarbon deposits appear to have an abiotic origin; and (3) to suggest future
studies that might help to achieve a more nuanced resolution of this sometimes polarized topic.