Chlorins in mid-Cretaceous black shales of the Demerara Rise: The oldest known occurrence

Liquid chromatography, multi-stage mass spectrometry (LC-MSn) of acetone extracts confirms the presence of mesochlorophyllone in the mid-Cretaceous black shales of Demerara Rise. This finding represents molecular confirmation of the oldest primary chlorins in the geologic record and is evidence for a chlorophyll a source for bicycloalkanoporphyrins in the Demerara Rise black shales.