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Fractures and Faults |
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Definitions:
Fractures are discontinuities with limited displacement. There are two types of fractures:
•Extensional Fractures involve displacement of adjacent blocks perpendicular to the fracture plane, i.e the blocks move away from each others in the direction of the least stress. Often, extensional fractures define "en échelon" array or even "conjugated en échelon array".
   
•Shear Fractures involves displacement of adjacent blocks parallel to the fracture plane, i.e the blocks slipped along each others. Structural geology called "kinematic of a fault" or "kinematic of a shear fracture" the relative sense of motion parallel to the discontinuity.
 
• Three modes of fractures have been defined, and here is how...
Extensional fractures and stylolitic joints are often associated. Together they reveal the orientation of the three principal stress axes.
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