# Reconstruction of the Subsurface of Al-Hassa Oasis Using Gravity Geophysical Data
## 5 Discussion
These basins are interrupted by higher-density areas, which are represented by the white spaces in between. Furthermore, the 3D model provides additional evidence to corroborate the notion that the southwestern basin is indeed the deepest. The model reveals a substantial structure that extends beyond the boundaries of the area and reaches a maximum depth of \(4.2\) km. By utilizing several geophysical techniques and considering additional factors, such as the proximity of the research area to the Ghawar oilfield and the anticipated tectoniccharacteristics in the region, we can draw the following conclusions based on the findings. The presence of fractures with distinct orientations both at the surface and in the subsurface offers insights into the complex geodynamic history of the region. Surface observations reveal predominantly E-W-oriented fractures, as indicated by [PERSON] et al. [45]. Conversely, subsurface data obtained from gravity surveys show the coexistence of both N-S and E-W fracture sets. The orientation of the principal stress (\(\sigma\)1), resulting from the Arabian-Eurasian plate collision along the Zagros belt, provides a plausible explanation for the genesis of E-W fractures. This tectonic interaction, characterized by significant compressive forces, will likely induce fracturing perpendicular to the \(\sigma\)1 direction, aligning with the observed E-W fractures. Conversely, the presence of N-S fractures, particularly noted in the subsurface and absent on the surface, suggests a different mechanism at play. These fractures may be associated with an extensional regime responsible for developing the Najd fault system. Furthermore, the general N-S orientation of outcrop belts and subsurface basins in the Al-Hassa area may derive from the Amar Collision's imprint, which established N-S trending structural patterns such as Al Nala anticline. This Precambrian event's legacy, coupled with a subsequent reactivation during the Hercynian Orogeny in the Devonian period, could have further accentuated the N-S structural predisposition. It is crucial to acknowledge the limitation of the outcrop data derived from a single outcrop study, which may not fully represent the area's complex fracture network. A comprehensive examination of additional outcrops could yield further insights into the interplay of tectonic forces and the development of fractures in the Al-Hassa area. This expanded analysis would enhance our understanding of the subsurface fracture patterns and their implications for hydrocarbon exploration and extraction in the region. Moreover, the observed density variations contributing to gravity anomalies may also be attributed to salt domes or diapirism, a hypothesis supported by the presence of such structures in the region, such as the Dammam Dome and the North Gulf Salt Basin [13]. This scenario underscores the multifaceted geological processes influencing the area's subsurface characteristics, further complicating the geophysical interpretation and emphasizing the need for a multi-disciplinary approach for unraveling the geological history and potential resource opportunities in the Al-Hassa region.