Structural Interpretation of Najaf Basin Using the Magnetic and Gravity Data, Central Iraq

Potential data interpretation is significant for subsurface structure characterization. The current study is an attempt to explore the magnetic low lying between Najaf and Diwaniyah Cities, In central Iraq. It aims to understand the subsurface structures that may result from this anomaly and submit a better subsurface structural image of the region. The study area is situated in the transition zone, known as the Abu Jir Fault Zone. This tectonic boundary is an inherited basement weak zone extending towards the NW-SE direction. Gravity and magnetic data processing and enhancement techniques; Total Horizontal Gradient, Tilt Angle, Fast Sigmoid Edge Detection, Improved Logistic, and Theta Map filters highlight source boundaries and the lineaments. Furthermore, the potential field was separated into regional and residual fields, and the depth to the tops of basement magnetic sources, faults and other 2D structures was estimated using power spectrum analysis and Source Parameter Imaging methods, respectively. The results show that the studied magnetic low represents a structural local basin developed in the transitional zone and was and still is suffering from many tectonic movements through the geologic time including differential subsidence. The basin is nearly circular with depths ranging from 14 km in the west to 10.5 km in the east, and a central ridge rising to 5.5 km. A two-dimensional forward model along an E-W magnetic profile is presented. The model reveals clear differences in the basement rock types, with weaker magnetic properties in the basin’s center and stronger ones along its edges. The research findings also indicate that the structural action that formed the basin has its effect which extends within the sedimentary cover depths and reaches to its upper formations or near surface formations.