Organic Petrography

Organic petrography is the study of the macroscopically and, more importantly, microscopically recognizable organic matter components initially of coal, but meanwhile more generally in sediments and sedimentary rocks. Organic-matter-rich rocks and coal are usually studied as 

In addition to maceral distribution, organic petro-graphers determine vitrinite reflectance as a measure of geothermal evolution of sedimentary organic matter. For more details of microscopic analysis see Taylor et al.(1998). 

---

Hutton, A. C. 1995. Organic petrography of oil shale. In Snape, C. (ed) Composition, Geochemistry and Conversions of Oil Shales. Kluwer Academic Publishers, Doordrecht, Boston, London, 17-33. 

The eastern Oklahoma coals were obtained from the Oklahoma Geological Survey Organic Petrography Laboratory where they had been crushed to -20 mesh and analysed on an as received basis (Table I). The whole, crushed coals were extracted for 48 hours with a 1 1 (v/v) mixture of chloroform/methanol using a soxhlet apparatus. Exhaustive extraction ensures that soluble compounds are removed and that the compounds produced during pyrolysis are derived from the organic matrix of the coal. 

Organic petrography and organic element analysis reveal that the source of the kerogen is algal (lamosites dominating) while other maceral forms dominate locally to form carbonaceous shale and humic coals. 

Cornford, C., Rullkotter, J. and Welte, D., 1979. Organic geochemistry of DSDP Leg 47a, Site 397, eastern North Atlantic Organic petrography and extractable... 

Hutton, A.C. (1988). Organic Petrography of Oil Shales, USGS short course, January 25-29, Denver CO. 

Hutton, A.C. (1991). Classification, organic petrography and geochemistry of oil shale, in Proceedings 1990 Eastern Oil Shale Symposium. University of Kentucky Institute for Mining and Minerals Research, Lexington, pp. 16-172. 

Figure 1. Coal and coal-derived particles identified by organic petrography techniques.

Rapid embedding in silica is particularly favourable for the good preservation of the organic matter, and this was surely the case with the well-preserved microstructures. But there is much indication from the thin section petrography that the Precambrian banded iron-formations were primarily deposited as carbonates (Lougheed, 1983)The origin of the embedding chert has been a major problem,... 

It is for these reasons that we have initiated this correlative study of peat petrography and peat industrial-chemical (coal quality) properties. Note that the information reported herein represents preliminary results based on a limited number of different types of peats that were analyzed for only a few coal quality tests (i.e., proximate analysis, ultimate analysis, and BTU content). Future studies will involve measurement of other petrographic parameters and include other industrial analyses (such as, gas and liquid yields, physical properties, organic chemical yields, and so forth). 

Bostick, N. H. Nicksic, G P. Bibliography and Index of Coal and Dispersed Organic Matter in Sedimentary Rocks Petrography, Catagenesis, Relation to Petroleum and Natural Gas and Geochemistry, Illinois State Geological Survey Urbana, HI. 1975 92 pp. 

Villar H. J., Piittmann W., and Wolf M. (1988) Organic geochemistry and petrography of Tertiary coals and carbonaceous shales from Argentina. Org. Geochem. 13, 1011-1021. 

The study by Freytet and Plaziat (1982) and the recent reviews by Freytet and Verrecchia (2002), Verrecchia (2002) and Alonso-Zarza (2003) provide excellent overviews of the petrography of lacustrine and palustrine deposits, and contain abundant photographs, information and references. In this section, only the main characteristic features associated with biogeochemi-cal lacustro-palustrine carbonate sediments will be described. Evaporitic sediments are the subject of another chapter (Chapter 10), and detrital sediments are not the topic of this book. As such, carbonates and organic sediments are the only facies that remain. 

D. H., 1984. Geochemistry and petrography of organic matter in sediments from Deep Sea Drilling Project Sites 545 and 547, Mazagan Escarpment. In Hinz, K., Winterer,... 

Rullkotter, J., Mukhopadhyay, P.K. and Welte, D.H., 1987. Geochemistry and petrography of organic matter from Deep Sea Drilling Project Site 603, lower continental rise off Cape Hatteras. In van Hinte, J.E., Wise, S.E. Jr et al. (eds). Initial Reports DSDP, 92, US Government Printing Office, Washington DC, pp. 1163-1176. 

Alpern, B., 1980. Petrographie du kerogene. In Durand, B. (ed.) Kerogen, Insoluble Organic Matter from Sedimentary Rocks. Editions Technip, Paris 339-383. 

Chapter 4). It is unnecessary to repeat this discussion except to note that this particular aspect of coal science (petrography) deals with the individual components of coal as an organic rock (Chapter 4) whereas the nomenclature, terminology, and classification systems are intended for application to the whole coal. Other general terms that are often applied to coal include rank and grade, which are two terms that describe the particular characteristics of coal. 

---