Upper bound on stylolite roughness as indicator for amount of dissolution

Abstract

Stylolites are rough surfaces formed by localized dissolution, mostly in carbonates and sandstones. They often account for a large degree of dissolution, and their impact on porosity and permeability is well recognized. Understanding their formation mechanism can advance our ability to predict their occurrence and effect on flow, which has appreciable geological and economical implications. Still, many fundamental issues concerning their structure and evolution are still unresolved. This manuscript studies the roughening of long parallel stylolites, which are one of three types of stylolite populations identified by us in a separate paper. Here we report measurements of stylolite surface roughness at a scale larger than ever measured before (10-2-10 1 m). Measurements were performed using ground-based-LIDAR on 6 naturally-exposed surfaces of >km long stylolites in Northern Israel. The outcome of these measurements is a topography model of the surfaces, on which different techniques for calculating their roughness characteristics were used. Our results show that up to scales of ~10cm, the average deviation of the surfaces from a planar surface is related to the scale by a power-law with an exponent H. The surfaces are thus defined as self-affine only up to ~10cm with H~0.7. Above this scale H decreases almost to zero. This observed upper-bound of self-affine roughness measured here for the first time has been predicted by theory [1, 2, 2bis]. Our measurements support these theoretical models and together with them present a scenario in which stylolites evolve from preferential dissolution along an existing surface that was initially smooth and progressively roughened with time. Such a mechanism of stylolites growth is different from previously suggested mechanisms for other classes of stylolite which might propagate sideways from an initial defect. Based on the theoretical roughening model that we adopted, the upper limit to fractality for this class of stylolites may be used as a measure of the amount of dissolution on stylolites. Indeed, the amount of dissolution of the stylolites in our field site which we calculated from the upper limit to fractality is comparable to our estimates of dissolution from two additional independent techniques.

Mechanical and physical behavior of high-porosity chalks exposed to chemical perturbation

“…It is a major mechanism in the pressure solution processes, which have been welldocumented in describing sedimentary and fault rock deformation (Durney, 1972;Rutter, 1983;Tada and Siever, 1989;Yasuhara et al, 2005), porosity-permeability evolution (Bjørkum and Nadeau, 1998;Ehrenberg et al, 2006), and development of stylolites in carbonate reservoir (Renard et al, 2004;Laronne Ben-Itzhak et al, 2012). One of the important implications of these processes is the formation of different pressure regimes in North Sea central graben, which impacts fluid pressure release and build-up (Swarbrick and Osborne, 1998).…”

Quasi-flexural folding of pseudo-bedding

“…Not unexpectedly, the stylolites that develop during the earliest stages of dissolution are tiny (millimeter scale), but progressively the teeth may achieve centimeterscale amplitudes. Final average amplitude of stylolite teeth can be used as a guide only to the minimum magnitude of material loss (Ben-Itzhak et al, 2012). Simpson (1985) and Alvarez et al (1985) demonstrated that pressure dissolution produced by gravitational loading during burial and diagenesis commonly generates parallel, evenly spaced stylolite surfaces that resemble fl aggy bedding.…”

Reconstruction of the pre-compactional thickness of the Zechstein Main Dolomite in northwest Poland

“…The stylolites differ in origin and morphology: from almost simple through wave-like to columnar and seismogram-like, according to the sequence of stylolite evolution (Fairbridge, 1968;Park & Schot, 1968;Strzetelski, 1977;Andrews & Railsbak, 1997;Sheppard, 2002;Sinha-Roy, 2002;Renard et al, 2004;Schmittbuhl et al, 2004;Brouste et al, 2007;Ben-Itzhak et al, 2012) (Fig. 2).…”

“…Solutes are then transported to the zones of lower stress, in consistence with the Riecke principle (Füchtbauer, 1974). As a result, the stylolite seams can be filled with residue composed of e.g., clay minerals and/or organic matter (Park & Schot, 1968;Neugenbauer, 1973;Bathurst, 1975;Larsen & Chilingar, 1979;Choquette & James, 1990;Matyszkiewicz, 1996;Środoń, 1996;Agosta & Kirschner, 2003;Ehrenberg, 2006;Ben-Itzhak et al, 2012;Rustichelli et al, 2012).…”