Slump folding in the Karaj Formation

Folds caused by gravitational gliding in unconsolidated and soft-sediments are called slump folds. They can form by layer-parallel shear. Such folds reflect the orientation of the palaeoslope in ancient settings. PhotoID799
The photograph was taken from the road section of Eocene Karaj Formation, near Karaj city (with a view to the WNW), 35° 50´ 11˝N, 51° 02´ 40˝E. Karaj Formation, ~ 3300 m thick, mainly composed of a heterogeneous assemblage of green tuff and tuffite, thin bands of marine shale, and igneous rocks. The thick turbidites with slump folding in the Karaj Formation may indicate a relatively deep water through and submarine fan. The Z-shaped asymmetric and overturned slump fold indicate northward palaeoslope. These conditions show stage 3 geometries (late translation of slump) of formation and develop of slump fold system by surging flow with flow accelerates and contraction increases downslope.

Photograph: Seyed Tohid Nabavi