Stylolites in Carbonate Rocks: Morphological Variability According to the Host Rock Texture

Stylolites are ubiquitous structures in carbonates that present a variety of morphologies. Besides being important structures in terms of rock compaction and deformation, stylolites control limestone permeability, which is influenced by their morphology and arrangement in connected networks. This study characterizes stylolite morphological parameters, such as length, thickness, filling by insoluble material, spacing and connectivity, to provide quantitative data on the relationships between stylolite morphology and carbonate host rock textures. A collection of thin sections from a variety of lithologies and geological settings was analyzed, showing that the stylolite length, thickness and morphology are interrelated and are controlled by the host rock textures. The results show that stylolite linearity, calculated as the ratio between the straight length and the length measured along the stylolite trace, varies according to the stylolite type. Higher stylolite thickness is observed in mud-dominated textures compared to grain-dominated ones but is independent of the stylolite type. There is no clear trend in terms of the amount of insoluble material collected by the stylolites and the rock texture or stylolite type. Analysis of stylolite spacing reveals that heterogeneity in grain size, grain sorting and composition controls stylolite formation.