Fracture zone, rock deformation

The slope had many fractures zone, joints inclined to slope direction, and many faults and poor rock qualities. This slope had also experienced three failures, including deformation, deflection and collapse in the upper and lower parts. 

Van Hise s treatment of metamorphism arose from the field observation that young rocks are often marked by numerous fissures and joints whereas older rocks show many signs of folding and flexure but few of fracture. He ascribed the difference to the physical conditions under which deformation occurred. Young rocls were deformed near the surface in what Van Hise called a zone of... 

Although Van Hise attributed the gross deformation of rocks to physical causes, he believed that their alteration was a chemical, or physico-chemical, problem. Thus, he maintained that a different set of chemical reactions characterized the alteration of rocks in each zone. In the zone of fracture, reactions typically occurred with the expansion of volume and the liberation of heat oxidation, carbonation, and hydration. In the lower zone, these reactions were reversed as pressure rather than temperature became the factor controlling chemical change. 

The above evidence establishes that fracturing and seismic behavior can extend well into the zone of mid to lower crustal metamorphism at rock pressures of —0.5-1 GPa. Veins preserve a valuable record of this brittle deformation they are fractures in which mineral mass has been deposited. The most common vein-forming minerals are quartz, calcite, and the feldspars, but a huge variety of other minerals are also observed. Fractures tend to focus flow, because they are zones of elevated permeability. Fracture flow is commonly approximated using the well-known expression from fluid mechanics for laminar flow between two parallel plates (e.g., White, 1979). For a set of parallel fractures, the flux is approximated by (e.g., Norton and Knapp, 1977) ... 

The use of the term damage zone (Knipe et al., 1994), is applied here to the distribution of minor faults and fractures within an ellipsoidal volume of rock surrounding a larger fault. Distributed deformation of this type is reported by several authors (Chester and Logan, 1986 Barnett et al., 1987 Koestler and Milnes, 1992 Gillespie et al., 1993 Peacock and Sanderson, 1994). While deformation is also distributed in a relay zone, we prefer to separate relay zones from damage zones. 

---