Abstract
This study presents the disposition of magmatic eruptions with a fault distribution in northwestern Saudi Arabia, where intensive magma invades the lithosphere. Structural and magmatic features are traced at successive depths through high-resolution magnetic anomaly pseudo-depth slices. The total horizontal gradient technique is applied to pseudo-depth slice magnetic anomalies to enhance the linear trends of faults and related magmatic activity. A comprehensive cross-section constructed from the projection of gradient horizontal maxima relative to pseudo-slices allows the visualization of the vertical behavior of faults and magma sources. Three major fault systems were identified, primarily aligned in the N-S, NE-SW and NW-SE directions. They are characterized by increasing length and width with depth. The N-S fault system is a major non-planar deep system throughout the area, affected by the NW-SE and NE-SW deep discontinuities. The evolution of these discontinuities with depth successfully shows magma uprising zones represented by a circular horizontal gradient, which starts to appear at a depth of 4500 m with a vertical continuity to the surface. They are interpreted as possible locations of ascending magma chambers or vents. The disposition of these magma sources with fault distribution can show a close relationship between the fault systems and the magma eruptions. The interpreted magma vents appear where the NE-trending transform faults intersect the NW or N-S fault zone. These intersections may represent weak zones that act as vertical conduits through which magma discontinuously erupts into the overlying crust, forming major volcanic fields in the eastern Red Sea.