Scaling and paleodepth of compaction bands, Nevada and Utah

Abstract

Measurements of the lengths and thicknesses of compaction bands in Navajo Sandstone from the Buckskin Gulch, Utah, field site demonstrate displacement‐length scaling with a power law exponent of ∼0.5, consistent with previous values obtained independently for compaction bands from the Valley of Fire, southern Nevada, site. Compaction energies calculated in this paper for the Utah bands, Gc = 55–120 kJ/m2, and for the Nevada bands, Gc = 30–60 kJ/m2, are consistent with those estimated from laboratory experiments despite major differences in band length, thickness, degree of grain fracturing, and remote stress state. Using the field measurements of bands from both sites in the recently proposed inverse relation between the magnitude of remote band‐normal compression and compaction band thickness predicts values of band‐normal compression of 24–30 MPa for the Utah bands and 31–62 MPa for the Nevada bands. Given that compaction bands at both sites are steeply dipping, these values correspond to a regional tectonic compression oriented subhorizontally at the time of band growth. The results suggest that the compaction bands formed at relatively shallow paleodepths of 0.92–1.3 km at the Utah site and 0.54–1.1 km at the Nevada site, in accord with estimates of the thickness of overlying stratigraphic cover during Sevier‐Laramide deformation at both sites. Growth of compaction bands at both field sites was likely facilitated by favorable host rock properties (well‐sorted, coarse‐grained, high‐porosity sandstone sequences) deformed within a thrust faulting tectonic environment.