Abstract

Ten or more samples of surface peat were obtained from each of six peat-forming environments in the Okefenokee swamp-marsh complex of southern Georgia. These peat-forming environments were chosen for study because they were found from core studies to have been the most important peat producers throughout much of the history of peat formation in the swamp.

The peat samples were dehydrated in alcohol, embedded in paraffin (using the methods of Cohen and Spackman, 1972), and sectioned (to 15 µ) with a sliding microtome. The microscopic features found to be most useful in characterizing the peats and relating them to their original depositional and vegetational environments were (1) their color (at 30×); (2) the ratio of framework to matrix; (3) the ratio of nonsedimentary to sedimentary constituents; (4) the proportions of remnants of plants assignable to particular plant species; and (5) the percentages of various accessory ingredients, such as fungal remains, fecal pellets, diatoms, insect parts, sponge spicules, quartz, and charcoal.

The peat-forming environments investigated were (1) the Nymphaea environment (open-water marshes dominated by floating aquatic plants); (2) the Carex, Panicum, and Woodwardia environments (glades or island fringes dominated by emergent aquatic plants); and (3) Cyrilla and Taxodium environments (tree islands and swamps). The peat sediments deposited in each of these regions were found to have distinctively different micropetrographic characteristics.

Aside from the qualitative and quantitative data collected for the purpose of defining the peat types, data were also collected in a form which could be used to determine the most likely eventual coal compositions of the peats. The herbaceous peats were found to have low percentages of pre-resinites (cell fillings and secretions), pre-sclerotinites (fungal remains), and fusinite (charcoal), and high percentages of pre-micrinites (fine granular debris). On the other hand, peats derived from tree vegetation had higher percentages of pre-resinites, pre-sclerotinites, and fusinites, and had relatively smaller amounts of pre-micrinitic materials. The former would probably result in a massive (unlaminated) dull coal, and the latter would probably become a somewhat brighter laminated type.

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