COLLABORATIVE RESEARCH: The Hydrology and Geochemistry of Holocene Mud-Islands in Florida Bay

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This study will examine the hydrology and geochemistry of pore fluids from Holocene Islands in Florida Bay over a two year periods. In particular we intend to test the following hypotheses: 1) Fluid movement is taking place beneath supratidal carbonate mud islands in Florida Bay in response to the reflux of hypersaline fluids formed on the island surfaces; 2) Dolomite is forming in response to the movement of these fluids and therefore dolomitization is more extensive in islands which have been islands throughout their entire history than in islands which have formed more recently; 3) The difference in fluid density amongst the various islands is a result of a climatic gradient, the highest salinities occurring in the areas of the bay with the lowest rainfall. The magnitude of the reflux is greater in those islands which show a greater difference in fluid density between the island and the adjacent bay. In order to test these hypotheses, we will (i) core between 10 to 20 islands which span the climatic gradient present in Florida Bay and which on the basis of previously published work have experienced sedimentological different histories, (ii) instrument two islands which occur at the ends of this climatic gradient with a series of nested piezometers and carry out geochemical analyses at regular intervals throughout the wet and dry seasons.