Faltenbild

Faltenbild refers to the geometric pattern formed by folds in layered rocks or other deformable materials as a result of tectonic or mechanical deformation. In structural geology, it describes the shape, orientation, and arrangement of folds, including the orientation of fold axes, the attitude of axial planes, and the curvature of limbs. The term covers macro-scale outcrop patterns as well as mesoscopic features seen in hand specimens or thin sections.

Common fold styles described in a Faltenbild include open or first-stage folds with broad wavelengths, tight or isoclinal folds with small wavelengths, and recumbent folds where the axial plane nears horizontal; specific subtypes such as chevron folds show angular hinge lines. Parasitic folds interrupt larger folds. The Faltenbild can be influenced by subsequent deformation and metamorphism.

Analysis involves field mapping, measuring fold geometry, using stereographic projection to plot fold axes and axials, building cross-sections, and sometimes 3D geological modeling. The term is used to interpret deformation history, infer stress directions, and correlate stratigraphy across regions.

Applications include petroleum geology, mining, and civil engineering, where understanding the fold pattern helps in predicting rock behavior, locating fractures, and evaluating stability.

In German literature, Faltenbild is sometimes used interchangeably with Faltenstruktur or Faltenbildung; classification can depend on scale and context.