A geological oceanography concept defining processes, measurements, or products used to describe the seafloor and its history. It applies when operational prerequisites and quality controls are satisfied and produces interpretable observations or derived maps. It does not yield reliable conclusions without validation, uncertainty handling, and integration of multiple evidence types. It materially affects knowledge of seafloor evolution, sediment transport, and marine hazards by improving the accuracy of interpretations. The concept is generally stable, though observational coverage and analytical methods improve over time.

Principle

Hydrocarbon generation from source rock depends on original organic richness (TOC and kerogen type), preservation conditions (anoxia, rapid burial), and thermal history determining maturation and hydrocarbon type (oil vs gas).

Demonstration

A marine anoxic basin accumulates fine-grained black shale with TOC of 3–6 % and Type II kerogen; with progressive burial and heating the kerogen enters the oil window (approx. vitrinite reflectance 0.6–1.2 %), generating and expelling liquid hydrocarbons into adjacent permeable sands.

Misapplication

Assuming a high TOC value alone guarantees a working source rock without assessing kerogen type, thermal maturity, or effective expulsion; or confusing terrestrial coal with marine source rocks when fluid types and maturation pathways differ.

Consequence

A valid marine source rock is the primary producer of hydrocarbons in many offshore petroleum provinces and controls the timing, volume and composition of generated fluids that populate reservoirs down-dip or down-migration pathways.

Reversal

A porous, organic-bearing rock that never experiences sufficient burial or heating will remain a geochemically immature organic-rich sediment and will not generate exploitable hydrocarbons; conversely, overcooked source rock produces gas or loses hydrocarbons to leakage.

Boundary

Refers specifically to marine depositional facies and excludes purely lacustrine or peat/coal-dominated terrestrial source systems; includes both continental-shelf and deeper-basin marine deposits but excludes anthropogenic organic accumulations.

Semantic Tension

Closely linked to but distinct from 'source potential' metrics (TOC, HI) and from reservoir concepts; the term emphasizes generation capacity rather than storage or transmissibility.

Synthesis

A marine source rock is a depositional lithology rich in preserved organic matter whose type and thermal history determine whether and when it generates oil or gas, thereby supplying fluids that can migrate into reservoirs.