(13) lecture 13 dip isogons and fold system.ppt

inter-limb angle
Geometric elements of folds
Review of geometrical elements of folds
Classification of folds (continue)
Based on four main features or properties:
1 direction of closing and facing
2 attitude of axial surface
3 size of inter-limb angle, and
4 shape of profile
5 dip isogons
Classification of fold based on direction of
closing and facing
Downwards-facing
upwards-facing
Facing towards the left
Classification of folds based on the attitude of axial surface
Trap for oil or gas
Classification of folds based on the inter-limb angle
Gentle
Open
Close
Tight
Isoclinal
A . Constant Bed
Thickness perpendicular to
Fold surface
B. Thickness constant
parallel to axial
surface
C. mon
center of curvature
D. Planar limbs
and sharp angular
hinge zone
Classification of folds based on the fold profile
Parallel folds
Detachment zone
Kink band
Markedly asymmetric chevron with a very long
limb and a very short limb
The band is the zone in which mon short straight limb
Bounded by the two adjacent fold surfaces
Classification of folds based on shape of profile
Variation in layer thickness
the perpendicular to
the axial surface
Method of measuring variation in layer thickness t in a is made at the point where the tangent
to the outer curve makes an angle  with the
perpendicular to the axial surface