Organic petrology and rock-eval studies on oil shales from the Lower Carboniferous Rocky Brook Formation, Western Newfloundland

Nine samples of oil shale from the Carboniferous Rocky Brook Formation along Rocky Brook in western Newfoundland were studied by incident light microscopy and geochemical analysis (Rock-Eval pyrolysis) to determine the maceral components, geochemical type, and maturation level of the kerogen fraction, and to determine the character and potential yield of the pyrolyzate. These oil shale beds are Type I lacustrine lamosites dominated by the maceral lamalginite. Optical properties indicate low to moderate thermal maturation but, as shown by geochemical analyses, the beds are immature and hydrocar- bons have not yet been generated. This relationship is characteristic of Type I deposits. The laminated strata generally contain greater than 5% organic carbon and yield upon pyrolysis sufficient petroleum product to be of economic interest; however, known bed thicknesses are too low to be currently attractive. More massive organic-rich beds may contain less than 4% organic carbon; the yield potential in these beds is severely restricted by an apparent mineral-matrix effect.