Provenance and stratigraphic-timing of marine-organism pDNA in Nanyang Oilfield crude oil

Ascertain whether the petroleum DNA sequences aligning to marine organisms (Chondrichthyes, Actinopterygii, Tunicata, and Mollusca) detected in Nanyang Oilfield crude oil are original in situ DNA from the Hetaoyuan Formation source rocks (oriDNA) or post-depositional ancient environmental DNA (paeDNA), and determine the timing of the implicated marine transgressions and the stratigraphic location of the host layers carrying these DNA fragments.

Background

Marine-affiliated pDNA signals suggest that at least one marine incursion influenced the basin after the mid-to-late Cretaceous emergence of key ray-finned fish clades. However, pDNA alone did not resolve when these incursions occurred (e.g., Paleocene/Eocene Hetaoyuan Member 3 versus other intervals) or where the DNA-bearing materials reside stratigraphically.

Establishing both the provenance class (oriDNA vs. paeDNA) and the stratigraphic-timing context is essential to corroborate marine incursion hypotheses for the Biyang Depression and to integrate molecular evidence with geological records.