Exercise 4 Solution

  1. There are similar porous zones of rock matrix porosity and zones with larger scattered solution openings that may or may not be from biological activity in Figure 13 of Williams and Kuniansky (2016). Most features and layering of the rocks in both logs are horizontal.
  2. The greatest difference between the older Floridan aquifer rocks in Figure 13 of Williams and Kuniansky (2016) is the more numerous horizontal bedding plane openings where the entire layer has been dissolved with some a meter thick; whereas the younger Biscayne Aquifer beds (Figure 14 of this book) haven’t completely dissolved.
  3. The unit (Figure 17 of this book) has practically no rock matrix porosity but does have some porosity in solutional-enhanced vugs and solution modified fractures and brecciated zones. One concludes that both age of the rock and the length of near surface exposure to meteoric water have a large impact on karstification. Additionally, the depositional environment [shallow sea or deeper sea]; fluid energy at deposition [wave action or fluvial influence near shore or further off shore]; biological activity [reef versus burrowing creatures or shell deposition in large layers]—all of which have a great impact on the relative amount of clays and sands or other impurities within the carbonate or evaporite units, the original porosity at deposition, and their subsequent ability to be dissolved or develop joints after deposition. The subject of carbonate rock formation is a field all its own and there is an excellent textbook on the subject by Scoffin (1987).

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Introduction to Karst Aquifers Copyright © 2022 by Eve L. Kuniansky, Charles J. Taylor, and Frederick Paillet. All Rights Reserved.