Structural Geology

Probably exam 1 stuff

Lithosphere

combination of crust and uppermost mantle - broken up into several tectonic plates

Tectonics

study of processes that deform earths lithosphere

plate tectonics

movement and interactions of tectonic plates

salt tectonics

deformation through vertical movement of salt - salt domes

neotectonics

active tectonic - study of ongoing tectonic processes and deformation

gravitational loading, displacement loading, thermal loading

weight of overlying rock column, plate collisions and magmatic intrusion, heating and cooling & expanding and contracting

Fracture

surface along which a rock breaks

brittle deformation

permanent change of a rock due to the growth of fractures and or sliding along fractures once they have grown

joint: opening

shear fracture - sliding

shear fracture - tearing

joint

a minute opening mode fracture with no shear displacement

joints

form perpendicular to the minimum principal stress

normal faulting regime

thrust faulting regime

slip strike regime

vein

fracture filled with minerals

dike

fracture filled with igneous or sedimentary rocks

regular joints

planar joints

irregular joints

non-planar (curviplanar) joints

systematic joints

planar geometry, parallel orientations, regular spacing

non-systematic joints

curved and irregular geometry, terminate against older joints from a systematic set

joint sets

joints with a similar orientation and morphology

joint system

array of two or more joint sets

joint faces

plumose structures that grow radially from a nucleation point (origin)

joint fringes

gradual twist hackles - smoothly emerge form main joint face

abrupt twist hackles - appear disconnected from the main joint face

twist hackles/en echelon fringe cracks - fractures within the join fringe.