GLY 326 Exam 2 Questions

-What are the types and properties of rocks that form as a result of brittle deformation? Types: Fault Breccias, angular rocks cemented together. Fault gouge, fine-grained clay-rich that forms along the fault plane. Mylonite, fine-grained, foliated rock, formed by recrystallization during faulting. Properties: fracture texture, like fractures, joints, faults. Angular clasts, foliation, cataclastic texture. -How do we determine the magnitude and direction of slip along a fault? Magnitude of slip is how far the two sides of the fault moved relative to one another. Direction of slip is measured on the fault surface; it is a specific angle. -Why do some rocks deform plastically and how does that happen? When a material is subjected to stresses that exceed its yield strength. Such as tension, compression, bending, torsion which allows for elongation, compression, buckling, bending, or twisting. -How are folds described in terms of their geometry? Folds are divided into domains where the shapes are cylindrical or conical, smoothly curved, or planar. There are fold axes, plunge lines, crest, and trough lines. -Why and how is a Fleuty diagram used? They are used for structural analysis to gain insights into the orientation and distribution of geological structures in a region. This can be used to understand the deformation history and tectonic evolution of an area. -How can subsurface structures be inferred from a geologic map? Strike and dip measurements denoted on a map, anticlines and synclines from the symmetry and mirroring of units. -What types of faults would we expect associated with each basic type of plate boundary? Divergent plate boundaries, have normal faults, the hanging wall moves down relative to the footwall. Convergent plate boundaries, have reverse and thrust faults, the hanging wall moves up relative to the footwall. Transform plate boundaries, have strike-slip faults, with left or right- lateral classifications. -How can Steno’s Laws be applied to understand the structural history of an outcrop? Law of Superposition, allows for chronological/relative ages of layers. Law of Original Horizontality, allows for determination of unconformities by looking at if layers are flat or tilted. Law of Lateral Continuity, allows us to determine a depositional or erosional hiatus. -What types of terrain will form proximal to plate boundaries resulting from different kinds of tectonic motions? Deep ocean trenches, volcanoes, island arcs, mountain ranges, and fault lines. -How can changes in a crystal structure make materials more susceptible to deformation? Defects, grain size, phase transformation, solid solution strengthening, and grain boundaries, can impact susceptible to deformation. This can strengthen or weaken the material. -What are the properties of each type of deformation mechanism and where are they located on a deformation map? Dislocation glide involves the motion of dislocation in a crystal lattice, on a deformation map it is prominent at moderate temperatures and strain rates. Twinning occurs when a portion of a crystal lattice mirrors another, leading to a change in crystal orientation, which can result in plastic deformation, on a deformation map it is favored at low temperatures and high strain rates. Grain boundary sliding involves the movement of grains relative to each other along grain boundaries, on a deformation map it is favored at intermediate temperatures and strain rates. Diffusional flow involves the slow, thermally activated motion of atoms or defects through the lattice, on a deformation map it is favored at high temperatures and low strain rates. -Why do the properties of the lithosphere change with depth and how does this happen? The changing properties are primarily driven by variations in temperature and pressure which influences mineral stability and phase transitions. As depth increases, the materials in the