ABSTRACT

The composition of palynomorph assemblages of Texas lignites from the Jackson Group (Eocene) is closely linked to depositional environment. Localities on the eastern Gulf Coastal Plain are included in the Fayette Delta System where lignite deposition is considered to have taken place in lower deltaic environments. Cluster analysis shows these palynofloras to be similar and usually dominated by Caprifoliipites/Salixipollenites, or Momipites, indicating dicotyledonous, tree-shrub dominated swamps. Some samples contain abundant Cicatricosisporites spores, suggesting marshy, fern dominated areas.

The San Miguel lignite, in Atascosa County, is located on the eastern margin of the South Texas, Jackson Group Lagoonal-Strand Plain depositional system. Cluster analysis separates these samples because of the rarity of Caprifoliipites-Salixpollenites, and the dominance in most levels of small tricolporates, such as Cupuliferoipollenites and Siltaria. Nyssa-Rhoipites, palm, and fern assemblages are also occasionally important. The lignite is hypothesized to have been deposited in a freshwater swamp lacking fluvial input behind a barrier island.