Comparative tectonofractography: Fracturing in 19 jointing provinces, experimental results, fracture mechanics considerations and province classification

This study presents a comprehensive synthesis of tensile fracturing phenomena from 19 provinces that display jointing in four continents, incorporating experimental results and fracture mechanic considerations. Three data assemblages are set in three tables (Tables 2-4) and provide the basis for the analysis. A series of new associations of various joint attributes emerges. They connect the joint type (single layer versus multilayer fracturing), the joint class (tectonic formation conditions) and joint relationship (joint orthogonality, the ladder pattern versus the grid pattern and joint rotation). These are further linked to lithology, fractography, joint propagation velocities and horizontal versus vertical propagation constraints. While arrest marks conspicuously occur on certain sandstones, plumes exclusively decorate particular igneous rocks. Tensile failure in glasses, ceramics, blasted rocks and in naturally fractured granitoids, as well as rarely in limestone, display two common features: smooth mirror planes that practically lack arrest marks and only rarely plumes imprinted on them, while their fringes are decorated by hackles. These are fractographic features that indicate unstable fracturing. Finally, a classification of jointing provinces is contemplated (Table 5).