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Porosity variability in limestone sequences

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Edited by: David Hopley
https://doi.org/10.1007/978-90-481-2639-2_244

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Abstract

Porosity is the state of being porous, as measured by the percentage of bulk volume of a rock or soil that is occupied by space, whether isolated or connected. In hydrocarbon-bearing limestone settings, subsurface porous strata containing the oil or gas usually underlie non-porous caprock through which hydrocarbons cannot pass. In settings, subsurface freshwater aquifers beneath caprock can become contaminated by saltwater intrusion during periods of drought. Islands of the Florida Keys consist of two types of emergent 125-ka limestone, a highly porous fossil coral reef with large voids and a less porous oolite with small grains and interstices. Both limestones are capped by impervious laminated Holocene calcrete whose dimensions differ greatly (Figure 1a and b). Porosity variability in the limestones is thought to be the cause. The less permeable oolite retained rainfall moisture longer, allowing longer periods of calcrete buildup. Reddish and brownish layers in both illustrated calcrete samples represent periods of influx of non-carbonate minerals on African dust. The hiatus or gap in these rock records represents an interval of >115 kyr during which no marine or terrestrial deposition is recorded.

Publication type Book chapter
Publication Subtype Book Chapter
Title Porosity variability in limestone sequences
DOI 10.1007/978-90-481-2639-2_244
Year Published 2011
Language English
Publisher Springer
Contributing office(s) St. Petersburg Coastal and Marine Science Center
Description 2 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Encyclopedia of modern coral reefs: Structure, form and process
First page 821
Last page 822
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