Novel C26 tetracyclic degraded bicadinanes in oil sands from the Haitoubei-Maichen Sag of the Beibuwan Basin, South China Sea

- Three C26 degraded bicadinanes were detected in oil sands in the Beibuwan Basin.
- Bicadinanes W, T and R are especially abundant in the associated oil sands.
- C26 degraded bicadinanes are similar to the C30 bicadinanes W and T in mass spectra.
- C26 degraded bicadinanes are positively correlated with C30 bicadinanes in abundance.
- C26 degraded bicadinanes have a geochemical significance similar to bicadinanes.