Tectonic Analysis of Lineaments in the Gara Anticline, Kurdistan, Northern Iraq

Satellite images were used to interpret the tectonic origin of lineaments in the Gara anticline. This anticline is one of the largest structures in the Zagros fold-thrust belt of Iraqi Kurdistan, near the northeastern boundary of the Arabian Plate. Lineaments of the Gara anticline were visually mapped on QuickBird images using the ESRI ArcGIS software and automatically extracted from Landsat 8 OLI data using the lineament extraction (LINE) module of PCI Geomatics software. The linear features obtained by both methods were statistically analyzed according to their orientation, length, frequency and density to provide a useful quantitative framework for interpreting the tectonic origin of these structures. Lineament orientations indicate a good symmetric relationship to the hinge of the Gara anticline. The results obtained from both techniques show five major sets: a hinge-perpendicular extension set (N 05 degrees E), a hinge-parallel extension set (N 85 degrees W) and three hinge-oblique shear-hybrid sets (N 45 degrees E, N 45 degrees W and N 75 degrees E). These dominant trends are consistent with previous field studies. Most of the lineaments in the Gara anticline are tectonic in origin and probably developed during the growth of the Gara anticline by a regional N-S-directed compression in the Mid Miocene time.