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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 445

Last Page: 445

Title: Pore Space in Holocene Carbonate Sediments: ABSTRACT

Author(s): Paul Enos, L. H. Sawatsky

Article Type: Meeting abstract


Mean porosity and permeability of Holocene carbonate sediments from Florida and Great Bahama Bank, determined for 74 samples by water-flow rates in a falling-head permeameter, are related to depositional texture as follows: grainstone 44.5% (range 40 to 53%), 30, 800 md (range 15,800 to 56,600 md); packstone 54.7% (45 to 67%), 1,840 md (32 to 9,300 md); wackestone 68% (64 to 78%), 228 md (38 to 6,570 md); very fine wackestone 70.5% (76 to 73%), 0.87 md (0.63 to 1.37 md); supratidal wackestone 63.5% (61 to 66%), 5,590 md (617 to 24,100 md).

The muddiest and finest grained sediments have the highest porosities but lowest permeabilities; this negative correlation between porosity and permeability is the reverse of the situation of carbonate rocks, even those as young as Pleistocene. High porosity and low permeability show a strong correlation with percentage of fines (< 64 µm). From capillary-pressure curves it is inferred that many of the pore entrances in muddy carbonate sediments are finer than 1µm, at least after drying.

Cementation rates for simple models of upper-phreatic-zone cementation calculated from the measured permeabilities would require excessive time to produce the degree of cementation present in late Pleistocene rocks of Florida and the Bahamas. Climate, especially rainfall and evapotranspiration, emerges as the rate-controlling factor in the most reasonable models of phreatic-zone cementation.

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Copyright 1997 American Association of Petroleum Geologists