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S.G. Fryberger

Publications and source records attributed to S.G. Fryberger.

3 recordsLinked to original sources
USGS1988

Pin stripe lamination: A distinctive feature of modern and ancient eolian sediments

Pin stripe laminations are a distinctive feature of modern and ancient eolian sediments. In sets of eolian ripple (or translatent) strata they represent deposition of silt and very fine sand in the troughs of the advancing wind ripples. In sets of avalanche strata they probably result from the downward settling of fine sand and silt within the moving avalanche to the interface of moving and unmoving sands. Wind tunnel experiments suggest that pin stripe laminations can also form in grainfall deposits. The textural segregation associated with deposition of the fine layers in most cases leads to early cementation along and near the finest sand and silt comprising the pin stripe lamination. The pin stripe effect seen in outcrops is usually due to resistance to weathering along such cemented zones. The cementation of the pin stripe laminations can occur early in the history of diagenesis and thus may provide clues to the post-depositional history of the rock. Pin stripe laminations in many instances represent the sequestering of the small population of ultrafine sediment present in most eolian depositional systems. They may prove useful in the recognition of ancient eolian sediments.

Sedimentary Geology↗
USGS1988

Early diagenesis of eolian dune and interdune sands at White Sands, New Mexico

The degree of early diagenesis in eolian dune and interdune sands at White Sands, New Mexico, is largely a function of the relationship between sand location and the water table. Most active and vegetation-stabilized dune sands are in the vadose zone, whereas interdune sands are in the capillary fringe and phreatic zones. Crystallographically controlled dissolution of the framework gypsum grains results in elongate, prismatic etch pits on sand grains from the capillary fringe and phreatic zones, whereas dissolution of sand grains in the vadose zone is slight, causing minute irregularities on grain surfaces. Vadose water percolating through the sand is manifest as meniscus layers. Consequently, dune sands in the vadose zone are cemented mainly by meniscus-shaped gypsum at grain contacts. Pendant cements formed on the lower margins of some sand grains. Cementation in the capillary fringe and the phreatic zone is more extensive than the vadose regardless of strata type. Typically, well-developed gypsum overgrowths form along the entire edge of a grain, or may encompass the entire grain. Complex diagenetic histories are suggested by multiple overgrowths and several episodes of dissolution on single grains, attesting to changing saturation levels with respect to gypsum in the shallow ground water. These changes in saturation are possibly due to periods of dilution by meteoric recharge, alternating with periods of concentration of ions and the formation of cement due to evaporation through the capillary fringe.

New Mexico↗