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The Microbial Pedigree of Freshwater Marl: Tracking Textures Through Early Burial and Diagenesis

Chelsea Pederson
Marine Geology and Geophysics, Rosentiel School of Marine and Atmospheric Science, Miami, FL, USA
[email protected]

Abstract

The Florida Everglades has been used as an analogue for paludal, fine-grained carbonate production (marl) (Mertz 1992). However, the nature of the microbial communities and the affect of early diagenetic alteration on the resultant calcitic mud are relatively unknown. The proposed research aims to provide an integrated geochemical and geomicrobial characterization of the freshwater marl deposits actively forming in Everglades National Park. This characterization will integrate depositional fabrics and textural features of the marl sediments with next-generation 16S rRNA microbial surveys and pore water geochemistry. This approach will make it possible to definitively assess the microbial pedigree of the primary deposits and evaluate processes of subsequent diagenetic alteration. This characterization will be used as a calibration to examine ancient (Pleistocene) marl deposits in the shallow subsurface of south Florida. Together, this modern and near-modern characterization of the depositional and diagenetic processes surrounding freshwater marl formation will address the longstanding questions of how microbial deposits are identified in ancient rocks, and the paleoenvironmental interpretation of marl deposits found throughout geologic time. Thus, the objectives are:

  • Characterization of depositional fabrics and textural features of marl sediments in Everglades NP;
  • Characterization of modern microbial communities in freshwater prairies and shallow push cores of marl sediments;
  • Geochemical analysis of pore waters and organics from marl sediments - an assessment of diagenetic changes due to Holocene transgression and pore water evolution (marine, brackish, and freshwater conditions).
  • Characterization of depositional and diagenetic products preserved in Pleistocene marl deposits in south Florida.
  • AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects