Scaling and paleodepth of compaction bands, Nevada and Utah

Abstract

[1] 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, G c = 55-120 kJ/m 2 , and for the Nevada bands, G c = 30-60 kJ/m 2 , 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 bandnormal 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.

Interpretation and analysis of planetary structures

“…Similar sublinear power-law scaling relationships (dashed lines in Fig. 19) have been documented along terrestrial veins and dikes (Olson, 2003) and along deformation and compaction bands (Fossen and Hesthammer, 1997;Schultz et al, 2008b;Tembe et al, 2008;Schultz, 2009). Igneous dikes are also being discovered in high-resolution images of the Coprates Chasma region of Valles Marineris.…”

“…The planet's layered sedimentary deposits are found to exhibit clear examples of fractures that occur at length scales of 1 km or less (Okubo and McEwen, 2007;Nahm and Schultz, 2007;Okubo et al, 2008;2009;Okubo, in press). A particularly well-exposed outcropping of subkm-scale joints has been recently discovered in southwest Candor Chasma, within the layered sedimentary deposits at the bottom of the canyon (Fig.…”

Propagation energies inferred from deformation bands in sandstone

“…The Buckskin Gulch site in southwestern Utah, USA, is described by Mollema and Antonellini (1996), Schultz (2009), Schultz (2011), Solum et al (2010, and Fossen et al (2011). Both pure and shear-enhanced compaction bands are known from this site (Fig.…”

“…Rudnicki 1980;Li 1987;Pollard and Aydin 1988;Cowie and Scholz 1992;Du and Aydin 1993;Schultz and Balasko 2003;Okubo and Schultz 2006), the controls on propagation of compaction bands remain the subject of active research. Compaction bands have been idealized as geologic anticracks that propagate at a critical value of strain energy release rate Sternlof et al 2005;Rudnicki 2007;Tembe et al 2008;Schultz 2009). Chemenda (2009Chemenda ( , 2011 modeled compaction band propagation by using a bifurcation analysis that predicted small, non-singular stress increases near band tips, seemingly consistent with the inferences of small-scale yielding and minor damage near field-scale compaction band tips made by Sternlof et al (2005).…”

Dynamical effects during compaction band formation affecting their spatial periodicity

“…Both sites involve as favorable characteristics to CB formation the presence of coarse-grained, high-porosity sandstone [Schultz, 2009]. CB-genic (i.e., suitable to promote CB formation) material is generally reported to range from lightly cemented sandstone to essentially uncemented sands [Holcomb et al, 2007].…”