RECONSTRUCTION OF THE SUBSURFACE CHLOROPHYLL MAXIMUM ZONES IN THE ANABAR–LENA SEA ( Late Jurassic–Early Cretaceous ) IN THE NORTHERN FRAME OF THE SIBERIAN CONTINENT

In the north of the Siberian Platform, subsurface chlorophyll maximum (SCM) zones have been reconstructed in Upper Jurassic and Berriasian sedimentary strata based on the geological and geochemical characteristics of the organic-matter composition. The reconstruction is based on gas chromatography–mass spectrometry (GC–MS) data on the individual composition of chloroform bitumen extracts, primarily the exceptionally high contents of isoprenoids (pristane and phytane), which are several times higher than those of co-eluting n-alkanes. In the aromatic fractions of bitumen, SCM is identified based on unusually high contents of chromans with an “isoprenoid tail”, which resulted from diagenetic condensation reactions between chlorophyll and phenols. The spatial location of the SCM zones is controlled by the shoreline of the Anabar–Lena Sea and the Siberian paleocontinent.