Since the early 1920s, most petroleum geologists have favored a biogenic theory for the formation of oil.
Topic
Theories about the origin of petroleum: biogenic vs. abiogenic
Framework
Old / New (with elements of Present Debate)
Main Point
The traditionally favored biogenic theory holds that oil is created from organic matter, but a competing abiogenic theory has emerged, suggesting that oil originated as hydrocarbons in the mantle and migrated upward. If the abiogenic theory is correct, it could mean there are undiscovered oil and gas reservoirs in unexpected places. Most Valuable Sentence: The last paragraph's first sentence sums up the significance:
P1: Background—Traditional View
Most geologists since the 1920s have thought that oil comes from buried organic matter that got transformed over long periods through heat and pressure.
P2: Introduction of Abiogenic Theory
A more recent, competing idea is that oil came not from dead plants and animals but from hydrocarbons that have been in the mantle since the earth formed. This oil would move upwards with methane gas through cracks in the earth.
P3: Scientific Debate and Evidence
Opponents of the abiogenic theory say hydrocarbons couldn’t survive the mantle’s heat, but supporters argue mantle conditions could allow it, pointing to the presence of diamonds (made of carbon) and experiments suggesting high pressure can preserve hydrocarbons.