Organic and clay-rich lignite samples from the upper Mississippi Embayment, United States, are known from organic petrography to be extremely palynomorph-rich; however, they are notoriously difficult to process. This leads to difficulty in determining the biostratigraphic placement of individual deposits and in interpreting depositional environments. Six ‘standard’ and non-standard processing techniques for extracting palynomorphs from these samples are presented and the results of each methodology analyzed. Results of these experiments led to the development of a new, hydrofluoric-acid-free processing technique which is presented, along with subsequent refinements to this technique. Samples processed with the new technique, referred to as the ‘O’Keefe technique’, are extremely palynomorph-rich and contain biostratigraphically significant taxa. These taxa allow the deposit to be placed within the middle Eocene Claibornian Stage, and show that it is likely correlative with NP 15.

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