Preferential orientation of arthropod-generated Diplocraterion parallelum and their statistical reliability as paleocurrent indicators
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| Authors: | Dashtgard, SE; Ainsworth, RB; MacEachern, JA |
| Year: | 2017 |
| Journal: | Palaios 32: 429-438 Article Link (DOI) |
| Title: | Preferential orientation of arthropod-generated Diplocraterion parallelum and their statistical reliability as paleocurrent indicators |
| Abstract: | Arthropods from the late Campanian (Late Cretaceous) of the Western Interior Seaway produced U-shaped Diplocraterion parallelum in mudstones along two closely spaced surfaces (10 cm apart), one of which corresponds to a maximum transgressive surface. Diplocraterion parallelum are widely distributed across both surfaces, with substantial variations in burrow orientations. Based on a comparison of paleocurrent indicators to burrow orientations, we demonstrate that D. parallelum are preferentially oriented parallel to the prevailing fair-weather wave propagation direction (wave-forced currents) that acted upon the colonized surfaces. There is an apparent maximum (34% above uniformity) preferential orientation of the burrows, attributed to the fact that wave-forced currents represent only one of several factors controlling shrimp burrowing behaviors. Based on this study, we propose that in the absence of paleocurrent data, Diplocraterion and other U-shaped burrows can be used to resolve flow directions, and that preferential burrow orientations >= 2% above uniformity are significant. However, it is noted that it is only possible to resolve 2-way flow directions (trend) from U-shaped burrows, as there is no way to determine vector directions. |
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