A qualitative and quantitative model for climate-driven lake formation on carbonate platforms based on examples from the Bahamian archipelago

Abstract

Lakes on carbonate platform islands such as the Bahamas display wide variability in morphometry, chemistry, and fauna. These parameters are ultimately driven by climate, sea level, and carbonate accumulation and dissolution. The authors propose a model that integrates climatological, geomorphological, and stratigraphic frameworks to understand processes of carbonate-hosted lake formation and limnological characteristics in modern day environments, with applications to carbonate lake sedimentary records. Fifty-two lakes from San Salvador Island and Eleuthera, Bahamas, were examined for water chemistry, basin morphology, conduit development, conductivity, and major ions. Using non-metric, multidimensional scaling ordination methods, the authors derived a model dividing lakes into either constructional or destructional formational modes. Constructional lakes were further divided into pre-highstand and highstand types based on whether their formation occurred during a marine regressive or transgressive phase. Destructional lakes are created continually by dissolution of bedrock at fresh/saline water interfaces and their formation is therefore related to changing climate and sea level. This model shows that lake formation is influenced by the hydrologic balance associated with climatic conditions that drives karst dissolution as well as the deposition of aeolian dune ridges that isolate basins due to sea-level fluctuations. It allows for testing and examining the climatic and hydrologic regime as related to carbonate accumulation and dissolution through time, and for an improved understanding of lake sensitivity and response to climate as preserved in the lacustrine sedimentary record.

Patterns of metal distribution in hypersaline microbialites during early diagenesis: Implications for the fossil record

“…These sulfides, which are absent in the Big Pond mats, may be attributed to a late-stage remobilization of progressively degraded organic matter and metal-bearing sulfides attending late diagenesis and/or metamorphic overprint. Accordingly, it is suggested that the metal distribution patterns reported for the Big Pond samples may be intrinsic to the formation and early diagenetic evolution of microbial mats in general, or at least to those associated with CaCO 3 stromatolitic constructions formed in hypersaline shallow marine and/or lake environments as reported for Big Pond (Park-Boush et al, 2014) and…”

“…5-10 m high) covered with vegetation. Big Pond has been cut off from any surface exchange with the ocean for approximately 4,000 years and functioned as a lake since then (Park-Boush, Myrbo, & Michelson, 2014;Park-Boush, pers. comm.).…”

“…The average temperature of the water column ranges from 30°C in the wet season to 50°C at the water column–sediment interface during the dry season. A nearly constant water level in the lake is maintained through seawater seeps at the northern end of Big Pond and by rainfall and evaporation in both basins (Glunk et al., ; Park‐Boush et al., ).…”