Coal Petrologic Investigation of Tropical and Subtropical Peats

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The purpose of this research is to investigate the petrographic and palynologic characteristics, surficial processes of formation, and early stages of coalification of several contrasting tropical and subtropical peat deposits located in the Caribbean/S. Florida region. This research represents a continuation of work previously supported by NSF, with emphasis on new and/or follow-up studies of certain sites and on certain promising new analytical techniques developed during the course of the previous work (such as, artificial coalification experiments). Three tropical and one subtropical coal-forming settings have been selected for study :1) the Moin coastal, palm swamp of Costa Rica; 2) the Changuinola swamp-marsh complex of Panama; 3) the Arecibo sawgrass-mangrove swamp of Puerto Rico; and 4) the Everglades-mangrove swamp-marsh complex of Florida. Although all of these settings have similarities, each exhibits one or more significant differences from the others and was selected because it is expected to yield new and essential information with which to interpret and predict the composition and geometry of the many ancient coals that have been reported in the literature to have formed in tropical shoreline-related settings. Since the focus of the previous grant was on the deposits in Panama and Costa Rica, this proposal puts more emphasis on the Arecibo and Everglades deposits. The methodology to be employed in this study will include: 1) field measurements of pH, salinity and other surface conditions; 2) field descriptions of peat sequences: 3) collection of surface litter and surface samples; 4) collection of oriented piston cores; 5) transmitted, reflected, and fluorescent light microscopy from microtome thin sections; 6) low temperature ashing and x-ray diffraction for assessment of mineralogic content; and 7) pollen analysis of surface and subsurface samples combined with radiocarbon dating, for interpreting the paleoecological and developmental history of the deposits.