Earth Structure An Introduction to Structural Geology and构造地质学概论和.pptVIP

1.2.1 Classification of Geological Structures I. Classification based on geometry (shape and form of a particular structure): a. planer surface b. linear surface c. curviplaner surface This classification may be the most important because it includes: folds, faults , joints, veins, cleavage, foliation and lineations. II. Classification based on geological significance: a. primary: ripple mark, cross bedding, mud cracks. b. local gravity driven: slumping. c. local density –inversion driven: salt dome (form due to variation in rock density). d. fluid-pressure driven: injection of unconsolidation material due to sudden release of pressure. e. tectonic: due to interaction between lithospheric plates. First four usually primary and nontectonic structures while the fifth is the main aspect of structural geology. III. Classification based on timing of formation : a. synformational: structure forms with initial deposition of rock. b. penecontemporaneous: structure forms before full lithification, but after initial deposition. c. postformational: structure forms after the rock has fully lithifide. IV. Classification based on Process of formation (the deformation mechanism) Fracturing: related to cracks in rocks. Frictional sliding: related to slip of one body of rock past another. Plasticity: deformation by internal flow of crystals without loss of cohesion. Diffusion: material transport in either solid-state or assisted by a fluid (dissolution). Stylolotes Combination: combinations of deformation mechanisms contributing to the overall strain. V. Classification based on Mesoscopic cohesiveness during deformation Brittle: structure forms by loss of cohesion. Ductile: structure forms without loss of cohesion. Brittle/ Ductile: deformation with both brittle and ductile aspects. ? VI. Classification based on Strain significance, in which a reference frame must defined (usually earth surface or the deformed layer):  Cont