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A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock. Fractures are commonly caused by stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. [1] Fractures can ...
At room temperature, intergranular fracture is commonly associated with altered cohesion resulting from segregation of solutes or impurities at the grain boundaries. [10] Examples of solutes known to influence intergranular fracture are sulfur, phosphorus, arsenic, and antimony specifically in steels, lead in aluminum alloys, and hydrogen in ...
The brittle–ductile transition zone is characterized by a change in rock failure mode, at an approximate average depth of 10–15 km (~ 6.2–9.3 miles) in continental crust, below which rock becomes less likely to fracture and more likely to deform ductilely. The zone exists because as depth increases confining pressure increases, and ...
Joints arise from brittle fracture of a rock or layer due to tensile stress.This stress may be imposed from outside; for example, by the stretching of layers, the rise of pore fluid pressure, or shrinkage caused by the cooling or desiccation of a rock body or layer whose outside boundaries remained fixed.
In geology, a dike or dyke is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion , either cutting across layers of rock or through a contiguous mass of rock.
In geotechnical engineering, rock mass plasticity is the study of the response of rocks to loads beyond the elastic limit. Historically, conventional wisdom has it that rock is brittle and fails by fracture, while plasticity (irreversible deformation without fracture) is identified with ductile materials such as metals.
In the upper crust, where rock is brittle, the shear zone takes the form of a fracture called a fault. In the lower crust and mantle, the extreme conditions of pressure and temperature make the rock ductile. That is, the rock is capable of slowly deforming without fracture, like hot metal being worked by a blacksmith.
Although the transition zone generally marks a shift from brittle rock to ductile rock, exceptions exist in certain conditions. If stress is applied rapidly, rock below the transition zone may fracture. Above the transition zone, the rock may deform ductilely if pore fluids are present and stress is applied gradually. [2]