Eolian sand dunes

Feature: Eolian sand dunesFormation: Nugget SandstoneAge: JurassicLocation: Moxa Arch, WyomingSeismic data owner: ?Contributor: Sumit Verma, Univ. Texas, Permian Basin, Midland, TX, USA

Summary

The Nugget Sandstone in Moxa Arch, southwestern Wyoming is a lower Jurassic eolian sand deposit, deposited as subtropical dune field and equivalent to the Navajo Sandstone of southwestern Utah. We analyze seismic attributes, primarily curvature and coherence, to identify the shape of the paleo-sand dunes and attempt to identify wind direction during the time of the paleo-wind deposition.

Modern Analogue

Figure 1 shows a Satellite image of Rub' al Khali, Arabia, which is one of the largest desert in the world. The blue arrow shows the general wind direction. The earth yellow color represents the dunal deposits, whereas the blue and white color represent the interdunal area.

Figure 1. A modern analogue for eolian sand dunes (after Aster Science Team, 2017).

Appearance on vertical seismic data

The Nugget Sandstone appears to be both vertically and laterally heterogeneous on vertical seismic slices, providing little insight into its geomorphology.

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Eolian sand dunes

Figure 2. Vertical slice through the seismic amplitude volume, showing the lateral variability of the 75-ms thick Nugget Sandstone formation.

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Eolian sand dunes

Figure 3. Stratal slices in the middle of the Nugget Sandstone show various attribute volumes delineate patterns similar to those seen in Figure 1. Slices through (a) strike of most positive principal curvature k1 corendered with its magnitude (b) P-impedance corendered with coherence, notice that the low P-impedance values are bounded by low coherence anomaly, and (c) GLCM homogeneity displayed as a bump map. Note most of the lineations in (a) trend NW-SE, while the low P-impedance values in (b) are bounded by low-coherence anomalies, and the lateral amplitude variation of the dunes as measured by GLCM homogeneity in (c) is less homogeneous than the interdune areas.

References

ASTER Science Team, 2017, NASA's satellite image of Rub' al Khali, Arabia. https://www.nasa.gov/multimedia/imagegallery/image_feature_1200.html , accessed 21 December 2018.

Verma, S., S. Bhattacharya, B. Lujan, D. Agrawal, and S. Mallick, 2018, Delineation of early Jurassic aged sand dunes and paleo-wind direction in southwestern Wyoming using seismic attributes, inversion, and petrophysical modeling: Journal of Natural Gas Science and Engineering, 60, 1-10.

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