Fault-related folding is an important process in compressive belts (Mukherjee et al. 2015). This horizontal section photograph shows a textbook example of a detachment horizon, which has developed asymmetric detachment fold (“A” in Fig. 1), fault-propagation fold (“B” in Fig. 1), and a box-fold (“C” in Fig. 1). The structure in the middle of the…
Fault-related folding is an important process in compressive belts (Mukherjee et al. 2015). This horizontal section photograph shows a textbook example of a detachment horizon, which has developed asymmetric detachment fold (“A” in Fig. 1), fault-propagation fold (“B” in Fig. 1), and a box-fold (“C” in Fig. 1). The structure in the middle of the photo (“B” in Fig. 1) is plausibly a fold-propagation fold, where white thin beds of laminated marble is sitting as an intermediate detachment horizon (Fig. 1). The fold geometry (“B” in Fig. 1) is usually tighter structure than asymmetric detachment fold with a long, gently dipping backlimb and a shorter, steeply dipping forelimb. The larger fold structure in the right side (“C” in Fig. 1) is more complex, with multiple sharp hinges separating straight limbs as a box lift-off anticline (e.g. McClay 1992; Mitra 2002, 2003) and small scale offsets due to penetrative strain (Burberry 2015). This fold is tighter in the core. See Mukherjee (2012) for a similar kind of fold in micro-scale.
These structures are well developed within the sequence of Devonian alternating layers of calcschist, meta-limestone turbidite (brown) and thin bands of laminated marble (white) and affected by east trending dextral Khabr shear zone with moderate dip to the north. This photo is taken from the Khabr Mountain (height: 3845m) (Geographic coordinates: 28°52´04ʺN, 56°23´56ʺE), Structural zone of Sanandaj-Sirjan metamorphic-ophiolitic Complex, southwest of the city of Baft, Kerman province, Iran.
A meso-scale faulted multi-detachment fold, Khabr area, Kerman, Iran, Photo by Seyed Tohid Nabavi
6