Introduction to structural Geology and its Types - Faults, Folds, Joints , Foliations

1. Structural Geology – Structural Features
Department
of
Civil
Engineering
Capital University of Science and Technology, Islamabad
Week: 09
Structural Geology

2. What is Structural Geology?
• Structural geology is a study of three-dimensional distribution
of rock units with respect to their deformational histories.
• The primary goal of structural geology is to use measurements
of present-day rock geometries to uncover information about
the history of deformation (strain) in the rocks, and ultimately, to
understand the stress field that resulted in the observed strain
and geometries.
• This understanding of the dynamics of the stress field can be
linked to important events in the regional geologic past.
Structural Geology – Structural Features
Department
of
Civil
Engineering
Capital University of Science and Technology, Islamabad
Week: 09

3. Economical Importance of
Structural Geology
• The study of geologic structures has been of prime importance in
economic geology.
• Folded and faulted rock strata commonly form traps for the
accumulation and concentration of fluids such as petroleum and
natural gas.
• Veins of minerals containing various metals commonly occupy
faults and fractures in structurally complex areas.
• Deposits of gold, silver, copper, lead, zinc, and other metals, are
commonly located in structurally complex areas.
• Structural geology is a critical part of engineering geology, which
is concerned with the physical and mechanical properties of
natural rocks.
Structural Geology – Structural Features
Department
of
Civil
Engineering
Capital University of Science and Technology, Islamabad
Week: 09

4. Structural fabrics and defects
• Faults
• Folds
• Foliations
• Joints
• These are internal weaknesses of rocks which may
affect the stability of human engineered structures.
Structural Geology – Structural Features
Department
of
Civil
Engineering
Capital University of Science and Technology, Islamabad
Week: 09

5. • Faults: A fault is a planar fracture or discontinuity in a volume
of rock, across which there has been significant displacement
along the fractures as a result of earth movement.
• Folds: A fold occurs when one or a stack of originally flat and
planar surfaces, such as sedimentary strata, are bent or
curved as a result of permanent deformation.
• Foliations: Foliation refers to repetitive layering in
metamorphic rocks. Each layer may be as thin as a sheet of
paper, or over a meter in thickness.
• Joints: Joint refers to a fracture in rock where the
displacement associated with the opening of the fracture is
greater than the displacement due to lateral movement in the
plane of the fracture (up, down or sideways) of one side
relative to the other
Structural Geology – Structural Features
Department
of
Civil
Engineering
Capital University of Science and Technology, Islamabad
Week: 09