## 4 Results
### Geological Interpretation, Site Location and Drilling Results  
TDEM tests in our study area have yielded results consistent with the presence of a Tertiary cover, as shown in the geological map of the area. However, the configuration of the contact between the Precambrian formations remains an unresolved enigma.  
Fortunately, thanks to the application of magnetic investigation techniques, we have been able to identify the point of contact between the formations below the Tertiary layer. This contact is clearly and distinctly in the northwest direction, as can be seen on the geological map. By superimposing our findings on the map, together with a precise extrapolation of this contact point, we have managed to visualise how it aligns relatively coherently with  
Figure 6: Situation of electromagnetic soundings and interpreted electrical conductivity profile formed by the electromagnetic soundings and apparent resistivity curves of the different electromagnetic soundings.  
the previously determined trajectory of this particular contact. This interesting result can be seen in Figure 7.  
This breakthrough represents a significant step forward in our understanding of the geological layout of the area. By linking the magnetic data with existing geological mapping, we have been able to infer the location of the contact between strata in the subsurface, providing valuable information for the characterisation of the region studied.  
Using these results and the information gathered from boreholes, we can propose sites for exploitation of the aquifer of greatest interest (Figure 8).  
The selection of drilling sites is based on two main criteria supported by magnetic scanning data, while electromagnetic (TDEM) data were not useful in this respect. These criteria focus on the most favourable lithology (S-1) and the point of contact between geological formations, which could indicate a more fractured zone (S-2).  
It is important to note that the location of borehole S-1 is determined on the basis of the lower magnetic susceptibility recorded in the results, looking for a greater presence of material of higher permeability. On the other hand, borehole S-2 is located in the contact zone between both geological formations, but within the formation of greatest interest.  
In relation to borehole S-1, the data collected indicate an estimated flow rate of around 2-3 L per second (L/s), which coincides with nearby boreholes and previous boreholes drilled in the same geological formation. As for borehole S-2, due to its location between two formations and its greater degree of alteration, the estimate of the flow rate is less certain, although its proximity to an impermeable edge suggests a lower estimate than in the previous borehole.  
Both boreholes (Figure 9) were drilled to a depth of 100 m in both cases, revealing an approximate flow rate of 3 L/s in borehole S-1 and 2 L/s in borehole S-2. These data, although requiring careful consideration due to the absence of regular testing throughout different seasons of the year, provide valuable context to support our site selection hypotheses and rationale.  
Figure 7: Contact path image between Formation 1 and 2. Precambrian (Formation 1 and 2), Tertiary (Formation 3) and Quaternary (Formation 4 and 5).  
Figure 8: Location of soundings (S-1 and S-2).  
Figure 9: Image of drilling rig at site S-1.  
The higher flow rate recorded in borehole S-1 supports the initial assumption of higher permeability at this location. On the other hand, the lower flow rate obtained in borehole S-2 evidences the nature of the contact between both formations. In addition, it is relevant to note that the material drilled in borehole S-1 was mostly identified as greywackes, whereas borehole S-2 passed through an alteration zone composed of quartz schists, greywackes and ultramylonites.