中国地质大学：《构造地质学》课程PPT教学课件（英文版）SUPERIMPOSED FOLDS AND FOLD MECHANISM

Review of folds

Review of folds

转折 面 A 拐 转折端 槽线 Geometric elements of folds inter-limb angle A.翼邵平直的稻皱的翼问角;以.弧形稻皱的翼闻角

Geometric elements of folds inter-limb angle

hinge lines axIs axial plane axial surface B (imaginary) Axis, axial plane and axial surface

Axis , axial plane and axial surface

A antiform B synform C neutral fold younger older(core) older younger(core) axial surface of anticline D. Anticline, fold faces upwards E antiformal syncline, fold faces downwards. F refolded recumbent anticline

D. Anticline, fold faces upwards E.antiformal syncline, fold faces downwards. F. refolded recumbent anticline

axial plane C overfold A upright B inclined crest hinges D recumbent trough E

-180 120 Classification of folds based on the inter-limb angle

Classification of folds based on the inter-limb angle

72

Detachment zone

Detachment zone

The band is the zone in which the common short straight limb bounded by the two adjacent fold surfaces Markedly asymmetric chevron with a very long limb and a very short limb

Markedly asymmetric chevron with a very long limb and a very short limb The band is the zone in which the common short straight limb bounded by the two adjacent fold surfaces

A symmetric S B asymmetric Symmetric and asymmetric folds Symmetric folds with limbs of equal length. Asymmetric folds with Limbs of unequal length

Symmetric and asymmetric folds Symmetric folds with limbs of equal length. Asymmetric folds with Limbs of unequal length N S