Tarim oils are multi-sourced from Cambrian–Ordovician with mixing and alteration.

Three oil families including terrigenous, suboxic marine and euxinic marine.

Cambrian shales deposited under oxic–suboxic environments were newly identified.

The Cambrian and Ordovician might have complex litho-organic facies.

Mixing of different maturity, biodegraded and recharged pristine oils.