Structural analysis using 3D digital outcrop model: A case study in Kebun 500 outcrop, Kedah, Peninsular Malaysia

Photogrammetry and digital outcrop modelling are the latest techniques used by various geoscience groups for Earth visualisation and research. This study showcases the structural analysis of a digital outcrop model in the Kebun 500 area, Kedah, involving drone photo collection, digital model construction, structural data extraction, and geological interpretation. The outcrop represents folded and fractured sedimentary rocks of the Permian-Triassic Semanggol Formation, situated adjacent to a major fault, the Bok Bak Fault. The digital model revealed a N-S strike direction and steep dips to the east in the sedimentary beds at the Kebun 500 outcrop. The rocks experienced flexural slipping on the bedding planes and locally folded into close-to-open folds. They can also be further classified into gently plunging-upright folds, gently plunging and moderately inclined folds, and moderately plunging and steeply inclined folds. The beds/folds are cross-cut by N-S striking, steeply dipping fractures, and NNW-SSE striking, inclined dipping reverse faults. The folds that occurred in the Kebun 500 outcrop are interpreted as parasitic folds. The identified fractures are also potentially associated with the Bok Bak fault system.