341 Sediments, Clastic (Posters)

Wednesday, 28 September 2016
9:00 AM - 6:30 PM
Exhibit Hall E/F

INNOVATIVE METHODS FOR SEDIMENT PEELS WITHIN SAND STRUCTURES

Paper number: 341-7
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Sediment peels can prove to be a highly effective method for studying sedimentary processes, allowing for enhanced opportunity for depositional analysis. Previously documented research by Skipper et al. (1998) suggested the use of polyurethane based expandable foam to make a sediment peel. This provided a simple method to obtain a rigid peel in roughly 30 minutes, suitable for wet and unconsolidated grains. However, the complexity of clean up, environmental safety and inconsistency of results stimulated the need for a superior method. Many published studies on sediment peels focus primarily on which adhesive works the best. Despite this being a significant factor, we found that the structural framework supporting the peel was equally important. To compliment this idea, we use a water-based expansive foam that solidified within 10 minutes. This method was able to capture the intricate details of the sedimentary structures in trenches on point bars on the Kansas River. Clean up required was minimal and the water based foam is more environmentally friendly. Attempts to make peels included the use of both flimsy sheet materials and burlap. These made decent peels, but allowed the peel to warp and shift once pulled from the sampled surface, which left gaps along bedding planes. The structure we found to work best was to use a rigid sheet of OSB and masonry lath. By screwing the lath to the sheets of OSB, no shifting of the abrasive catch material occurs. Also, the masonry lath is roughly 1/8 of an inch in depth, allowing for further penetration into the sand. We also tested a variety of adhesives. Most of the adhesives tried on this structure produced improved results, but the best results were seen with the use of medium expansion foam. Spreading this foam across the lath and applying it before expansion occurred allowed for the lath itself to make contact with the sediment. This was the first step of penetration. Keeping the surface in contact for 2-3 minutes further allowed the foam to expand into the sediment and adhere to the particles. When removing the board from the sediment surface, it needs to be pulled perpendicular to the face, to reduce sideways shears that would result in loss of sand particles due to abrasion. Because of the rigidity of the lath, the sediment surface needs to be as planar as possible to increase the amount of surface contact.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-287725

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