Saudi Arabia covers most of the Arabian Peninsula and is characterized by tectonic regimes ranging from Precambrian to Recent. Using gravity data to produce the lateral boundaries of subsurface density bodies, and edge detection of potential field data, a new subsurface structural map was created to decipher the structural framework controls on the distribution of gold deposits in Saudi Arabia. Moreover, we detected the relationships between major structures and mineral accumulations, thereby simultaneously solving the problem of edge detectors over complex tectonic patterns for both deeper and shallower origins. Analytic signal (ASg), theta map (TM), TDX, and softsign function (SF) filters were applied to gravity data of Saudi Arabia. The results unveil low connectivity along the Najd fault system (NFS) with depth, except perhaps for the central zones along each segment. The central zones are the location of significant gold mineralization, i.e., Fawarah, Gariat Avala, Hamdah, and Ghadarah. Moreover, major fault zones parallel to the Red Sea extend northward from the south, and their connectivity increases with depth and controls numerous gold mines, i.e., Jadmah, Wadi Bidah, Mamilah, and Wadi Leif. These fault zones intersect the NFS in the Midyan Terrane at the northern part of the AS, and their conjugation is suggested to be favorable for gold mineralization. The SF maps revealed the boundary between the Arabian Shield and Arabian Shelf, which comprises major shear zones, implying that most known mineralization sites are linked to post-accretionary structures and are not limited to the Najd fault system (NFS).

The geotechnical parameters of near-surface sediments in Jizan city have been assessed through shear wave velocity (Vs) from twenty-two profiles of multi-channel analysis of surface waves (MASW) through Jizan city. The Vs varies between 106 to 560 m/s indicating wide range of soil stiffness properties. While the allowable bearing capacity, q_a varies from less than 1 kg/cm² at sites till depth 21m indicating very soft /loose materials; these are considered by building codes as special cases and increased into 2.5 kg/cm² suggesting stiff or medium dense materials Moreover, q_a reaches 6.5 kg/cm² indicating dense materials, while reaches 8.5 kg/cm² suggesting the presence of very dense materials. Accordingly, the allowable bearing capacity at a depth of 13 m is less than the recommended values for foundation materials by building codes. Jizan city differentiated into two zones; Jizan salt dome to the west and sabkha deposits to the east. Several weakness zones in the Jizan salt dome zone have been detected with significant variations in the topography of salt rock. While sabkha deposits have low shear strength which requires engineering treatment before construction. Furthermore, shear modulus varies both vertically and laterally through Jizan city where values of shear strength of the near-surface sediments overlying salt rocks are greater than those of sabkha zone. Therefore, deep foundation and ground improvement are highly recommended.