Assertion: crude oil | /r/HasProperty | generated in fine-grained sedimentary
Facets:
value: by geothermal action on kerogen
type: CAUSE
Source sentences:
text: Oil and natural gas is believed to have been generated in significant volumes only in fine-grained sedimentary rocks (usually clays, shales, or clastic carbonates) by geothermal action on kerogen, leaving an insoluble organic residue in the source rock.