Controls on petroleum formation (organic origin): Which factor listed below does not principally govern the mechanism by which petroleum forms from organic matter in sediments?

Introduction / Context:
Petroleum generation from organic matter proceeds through diagenesis, catagenesis, and metagenesis. The key controls are biochemical activity, temperature history, pressure, and time, which together drive the transformation of kerogen into liquid and gaseous hydrocarbons.

Given Data / Assumptions:

• Organic source material deposited in sedimentary basins.
• Transformation occurs under burial with limited oxygen.
• We focus on primary governing factors.

Concept / Approach:
Bacterial action (especially anaerobic) and thermal maturation are central to early and middle stages. Pressure and time enable compaction, expulsion, and continued reactions. Soil pH, while locally affecting near-surface environments, is not a principal control on deep subsurface kerogen maturation pathways traditionally emphasized in petroleum geology.

Step-by-Step Solution:

Verification / Alternative check:
Academic summaries of petroleum systems emphasize temperature history, time, pressure, and biological mediation; pH appears mainly in surface diagenesis contexts and is not a headline control on generation kinetics.

Why Other Options Are Wrong:

Common Pitfalls:
Over-attributing near-surface geochemical factors like soil pH to deep basin maturation processes.

Final Answer:
pH of the soil