Final answer:
The petroleum-related species found in sedimentary rocks that serves as a precursor to hydrocarbons is kerogen. It originates from decomposed organic material over millions of years and is present in source rocks that may generate oil or gas. Kerogen eventually transforms into various hydrocarbon compounds found in crude oil through geological processes.
Step-by-step explanation:
The precursor to hydrocarbons found in sedimentary rocks that serves as a source material for petroleum is known as kerogen. Kerogen is a mixture of organic chemical compounds that contributes to the formation of fossil fuels. It is derived from the decomposition of microscopic plants and animals in oceans that were subsequently buried under sediment, undergoing high pressures and heat over millions of years. The sedimentary rocks rich in this organic matter, also called source rocks, can potentially generate oil or gas when subjected to sufficient heat.
Petroleum or crude oil is a complex mixture of hydrocarbons that includes lighter molecules such as octane, which is used in gasoline, as well as heavier molecules found in products such as tar/asphalt and lubricants. Through refining processes, these distinct hydrocarbon chain lengths are separated to produce various petroleum products. The majority of crude oil is consumed for energy production while a smaller portion is used for manufacturing petrochemical products.