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

本研究将对佛罗里达湾全新世岛屿的孔隙流体进行为期两年的水文和地球化学研究。我们特别打算检验以下假设：1)佛罗里达湾潮上碳酸盐泥岛下面正在发生流体运动，这是对岛屿表面形成的高盐流体回流的反应；白云岩的形成是对这些流体运动的反应，因此白云化作用在整个历史上一直是岛屿的岛屿上比在最近形成的岛屿上更为广泛；3)各岛屿之间流体密度的差异是气候梯度的结果，海湾中降雨量最少的地区盐度最高。这些岛屿的回流强度更大，表明岛屿与邻近海湾之间的流体密度差异更大。为了测试这些假设，我们将(i)在10到20个岛屿之间进行核心研究，这些岛屿跨越佛罗里达湾目前的气候梯度，并且根据先前发表的工作，经历了不同的沉积学历史；（ii）用一系列嵌套的气压计测量位于这一气候梯度末端的两个岛屿，并在整个干湿季节定期进行地球化学分析。

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.