Structural Diagenesis, Early Embrittlement and Fracture Setting in Shallow-Water Platform Carbonates (Monte Alpi Southern Apennines, Italy)

Bed-perpendicular diffuse fractures are common features in carbonates that could be affected by early embrittlement process, which may enhance vertically persistent, opening-mode fractures during the first stages of diagenesis. Early-developed fractures could be independent of tectonics and form a background structural network at different scale. This study focuses on the structural, stratigraphic and petrographic characterization, from outcrop- to micro-scale of Lower Cretaceous, shallow-water, tight limestones pertaining to the Inner Apulian Platform paleogeographic/tectonic domain. These carbonates consist of a wide spectrum of inner platform-platform margin calcareous facies, namely mudstones, wackestones, packstones, grainstones, bindstones, floatstones and rudstones. The presented work is addressed on understanding the development of the early diagenetic features which occurred during the first stages of the sediment lithification processes and the description of the formation, geometry and distribution of the contemporaneous and subsequent structural elements. Field analyses in concert with laboratory analyses unrevealed the main structural-diagenetic events which affected the studied shallow-water carbonates. Petrographic analyses highlight early fractures are intrinsically related to the host rock pore type. Finally, evolution of the fracture network is summarized in a conceptual model by taking into account the several tectonic phases which affect the Monte Alpi sector