PARTIAL RESOLUTION OF SOURCES OF N-ALKANES IN THE SALINE PORTION OF THE PARACHUTE CREEK MEMBER, GREEN RIVER FORMATION (PICEANCE CREEK BASIN, COLORADO)

Systematic variations in the C-13 contents of individual extractable n -alkanes (C-16-C29) can be modelled quantitatively and interpreted as indicating contributions from at least five distinct sources. These ap pear to be cyanobacterial (C-16-C18, deltaC-13 = -37 parts per thousan d vs PDB), phytoplanktonic (C-16-C23, delta = -32 parts per thousand), chemoautotrophic bacterial (C20-C29, delta = -38 parts per thousand), phytoplanktonic or heterotrophic bacterial (C20-C29 delta = -30 parts per thousand), and vascular plants (C23-C29, delta = -29 parts per th ousand). Hydrous pyrolysis of related kerogens yields large quantities of additional n-alkanes with different and much more uniform delta va lues. The latter materials are apparently derived from the thermolysis of aliphatic biopolymers whose presence in the Green River Oil Shale has been recognized visually.