Mangrove-generated structures and depositional model of the pleistocene fort thompson formation (Florida plateau)

• DOI: 10.1007/bf02536763
• Publication Date: 2006-12-13T06:12:14Z
• Authors: Gianni Galli
• Keywords: 13. Climate action; 14. Life underwater; 15. Life on land; 01 natural sciences; 0105 earth and related environmental sciences

The carbonate Fort Thompson Formation (Pleistocene) of the South Florida platform consists of regular alternations of marine, brackish and terrestrial lithofacies 1) mollusk packstones and grainstones (estuaries, banks, patch-reefs, bioturbated nearshore zone, marsh flat); 2) mangrove peats; 3)Helisoma wackestones (saw grass prairie, freshwater pond, buttonwood hummock), and 4) freshwater swamp. The corresponding environments represent a low-energy coastline. Lithofacies are arranged into stacked sequences. Three modal asymmetric regressive parasequences (‘A’;‘B’;‘C’) reflect relative sea-level rises; the lower part of sequence ‘A’ is analogous to the Lofer cycles; sequence ‘B’ is similar to the Holocene cycle from Florida Bay; sequence ‘C’ is analogous to present-day swamp cycles forming in the Everglades. Correlations of transgressive surfaces point out a wedge with parasequences thinning-out and disappearing towards a hinge located to the west. Geometrical considerations suggest that rotational subsidence was initially the main control on sedimentation and led to the deposition of parasequences ‘A’. Subsequently, its attenuation highlighted eustatic changes which are more apparent higher up in the Formation; parasequences ‘B’ and ‘C’ formed under the main influence of eustatic factors.