Interaction between pressure solution and clays in stylolite development: Insights from modeling

Abstract

Stylolites are localized dissolution surfaces commonly found in sedimentary rocks. Stylolites have been extensively studied due to their important role in controlling dissolution, precipitation, deformation, and fluid transport in rocks. Field observations indicate that stylolite formation and morphology are strongly correlated both with the surrounding stress and with the distribution of clays within the host rock, yet the mechanism by which they form remains enigmatic. We present results from a newly developed two-dimensional Spring-Network Model that studies stylolite formation by pressure-solution with and without the presence of clays, where clays play a role of enhancing pressure solution. We use our model to test the relative role of stress and clays in controlling the localization of dissolution into stylolites. In contrast to the common paradigm, our results suggest that pressure solution alone, in the absence of catalyzing clays, does not lead to spontaneous localization of dissolution into stylolites. Instead, we propose a new coupled clay-pressure-solution feedback to localize stylolites, a coupling that we observe in our model: a region with a slightly larger clay fraction will experience enhanced dissolution, and will thus accumulate more residual clays, which will act to further enhance pressure solution in that region, and accumulate even more clays. Stress is a necessary component in this feedback as it controls the direction of stylolite propagation, and facilitates lateral propagation.

Interfacial energy effects and the evolution of pore size distributions during quartz precipitation in sandstone

“…However, alternative mechanisms might produce similar effects. Clusters of clay minerals and clay coatings on quartz grains could affect quartz precipitation and act to inhibit mineral precipitation (Heald and Larese, 1974;McBride, 1989;Walderhaug et al, 2006;Aharonov and Katsman, 2009); however, the proportion of clay in the sandstone formation is extremely low, comprising only $0.2% by volume (Walderhaug and Bjørkum, 2003), and it seems unlikely that such a small amount of material could account for the magnitude of porosity preservation measured in the present study. Moreover, BSE images show that clay minerals are absent from most of the small pores between the quartz grains (Fig.…”

The Role of Pressure Solution Creep in the Ductility of the Earth’s Upper Crust

“…From experiments using an atomic force microscope (Greene et al, 2009;Meyer et al, 2006) proposed new feedback that couples clays and pressure-solution and localizing dissolution along a flat interface (Aharonov and Katsman, 2009). This is discussed in more details in Section 3 & 4.…”

Millimetre-Scale Localisation of Strain and Dissolution in Oolitic Grainstone

“…Ongoing dissolution favoured surfaces that were bedding-parallel. These observations support previous research stating that mature stylolites are developed from initial interfaces (Ebner et al, 2010) and that the presence of clays is a necessity for localised stylolite development (Aharonov and Katsman, 2009). …”

“…Initial interfaces are early-stage primitive stylolite surfaces that, after progressive dissolution, may form into continuous stylolite seams (Ebner et al, 2010). The development of initial interfaces into mature stylolites appears to require clay minerals along the interface which enhance localised dissolution (Aharonov and Katsman, 2009). Minor phases such as clays and quartz are also known to influence the roughness and morphology of stylolite teeth (Ebner et al, 2010) and affect the relative rate of dissolution on each side of the stylolite seam (Koehn et al, 2012).…”