Pressure solution-assisted diagenesis and thrusting-related deformation of Mesozoic platform carbonates

Abstract

Depositional and diagenetic processes profoundly control the structural evolution of shallow-water carbonates through time. We focus on the Lower Jurassic platform carbonates pertaining to the southern Apennines fold-and-thrusts belt, Italy, by performing 3D digital outcrop modeling, field structural analysis, and microstructural investigation. Results show that pressure solution of the platform carbonates was affected by the grain size of single beds. Since early diagenesis, pressure solution localized within the coarser-grained carbonate beds, forming wave-like solution surfaces. Crosscutting relations among blocky cements, bed-parallel solution surfaces and high-angle veins show that pressure solution occurred during burial diagenesis with formation of wave-like solution surfaces, and during Late Miocene tectonic burial with formation of seismogram-like solution surfaces. The tectonic burial postdated the thrusting-related flexural slip folding and small-scale thrusting of the platform carbonates. Small scale thrusting took place by means of shearing of the bed-parallel heterogeneities, and formation of bed-oblique slickolites resulting in the development of back thrusts characterized by flat-ramp-flat geometries. The main results of this work are synthesized in a six-stage synoptic scheme reporting the structural evolution of the platform carbonates. Outcomes are helpful for the better assessment of geofluid production/storage from/in fractured platform carbonates pertaining to fold-and-thrust belts.