Aryl Isoprenoids of Paleozoic Oils of Southeastern Western Siberia (Russia)

Summary Arylisoprenoids (m/z 134) were found in the Paleozoic oils of southeastern West Siberia (Russia). Our studies have shown absent of arylisoprenoids in the oils and sediments of the Togur and Bazhenov Formations. This indicates a different composition of bioproducers and sedimentation conditions of organic matter. The presence of arylisoprenoids in the composition of the studied Paleozoic oils is evidence of periodic occurrence of anoxic conditions in the photic layer of paleobasin waters. The degree of anoxia of the photic layer during the formation of the organic matter by the arylisoprenoid index (AIR) was estimated for Paleozoic oils. Also, relative arylisoprenoid content (arylisoprenoid/n-alkanes ratio) was estimated for Paleozoic oils. The values of the arylisoprenoid index in the studied Paleozoic oils are determined not only by the conditions of formation of syngenetic organic matter of the source rock but also by the processes of catagenesis.