Chemical and Petrographic Classification of Kerogen/Macerals

Abstract

The use of the term «kerogen», originally described as the organic matter in oil shale, has been extended to include all nonsoluble solid organic matter in sedimentary rocks. Kerogen is divided into «types» based on elemental composition and potential maturation path. «Maceral» nomenclature, originally developed to describe the organic components of coal, has also been extended to source rocks and, later, oil shale. The extension and overlap of these two fields creates problems as attested to by the proliferation of vitrinite terminology and the application of the term vitrinite to organic matter that is not clearly derived from woody tissue. Other problems include the fundamental complex and wide-ranging nature of Type II kerogen which is now acknowledged to be a highly heterogeneous material.