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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 986

Last Page: 986

Title: Porosity and Textural Characteristics of Eolian Stratification: ABSTRACT

Author(s): Christopher J. Schenk

Article Type: Meeting abstract


An analysis of experimentally formed eolian stratification has shown that processes of deposition are the major factors controlling the primary porosity and texture in the avalanche, grainfall, and ripple-produced types. Avalanche stratification generally exhibits the highest primary porosity (avg 47%) because of loose packing and grain arrangements that occur as a mass of sand shears downslope. Wind ripple-produced stratification has the lowest primary porosity (avg 39%) due to the relatively close packing and the presence of finer grained sublayers developed near the base of each inversely graded ripple stratum during ripple migration. Primary porosity of grainfall stratification (avg 43%) is usually intermediate between that of avalanche and ripple-produced deposits be ause the packing is between the avalanche and ripple produced types.

Avalanching forms the high-angle, porous, lee-slope stratification commonly observed in eolian deposits. Ripple-produced stratification is formed in two principal localities--on the low-angle windward slope where potential for preservation is poor, and on the lower part of the lee slope where preservation potential is excellent. The ripple deposits, produced by winds moving across the lee slope, form the tangential foreset-to-bottomset stratification common to eolian dunes. The relatively low porosity observed in these deposits is due to the stratification being composed of ripple-produced deposits. Grainfall stratification has a poor preservation potential because of redeposition by avalanching on the upper part of the lee slope. Grainfall on the lower lee slope usually occurs on a r ppled surface, and these grains are incorporated into the ripple-produced stratification being formed at that site.

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