## 3 Methods and Material
### Geophysical Survey
#### 3.4.2 Gravimetry  
Gravimetric measurements provide an informative picture of the gravity field and the geology of the area. The detailed mapping resulted in maps of the complete Bouguer and residual anomalies. The qualitative interpretation was focused on determining the exact location of depression and elevation areas and distinct tectonic lines. Determining the density of the basic petrographic rock types made it possible to interpret the gravimetric profiles. The density values were used to determine the distribution and the depth of the Humenne Unit [28; 29; 30].  
There is a relatively wide range of density parameters (Table 3). Volcanic complexes or volcanaclastics show low densities, while intrusive igneous bodies such as diorite and granodiorite porphyries have increased density values. The sedimentary complex of Cretaceous sediments of the Humenne Unit shows the highest values.  
Field gravimetric measurements were taken by conducting detailed profile mapping. The positions of the measured gravimetric points were recorded using GPS and marked in topographic maps at a scale of 1:10,000. The gravity values were measured at all points with the specified altitude. Gravity measurements were performed with a CG-3 gravimeter.  
A total of 206 points and 22 checkpoints were measured. The accuracy of the measurements was calculated from the independently determined gravity values at the control points:  
\[\mathrm{m_{g}}=\pm\sqrt{\frac{[vv]}{n-v}}[\mathrm{mGal}]=0.005\;\mathrm{mGal} \;\left(0.05\;\mathrm{\upmu ms^{-2}}\right) \tag{1}\]  
Figure 4: Geothermogram describing the depth-temperature dependence of the Humenne Mountains. [22].  
[PERSON]'s equation [31] was used to calculate the normal field. [PERSON]'s reduction was calculated using [PERSON]'s second-stage expansion. The classical Bouguer plate was replaced by a spherical plate up to 166.7 km, so the Boulard term is not used. The final phase is the calculation of topographic corrections up to a distance of 166.7 km around each measuring point. The actual shape of the relief found during field measurements was also taken into account. The result is a curve of complete Bouguer anomalies for a reduction density of 2.67 g\(\cdot\)cm\({}^{-3}\) calculated according to the equation:  
\[\Delta\text{g}_{\text{B}}(\varphi,\lambda,\text{h})=\text{g}(\varphi,\lambda, \text{h})-\text{g}_{\text{n}}(\varphi)+\text{R}_{\text{F}}(\varphi,\lambda)- \text{\sigma}_{\text{g}s}(\text{h})+\text{T}(\varphi,\lambda,\text{h}) \tag{2}\]  
where:  
g(\(\varphi,\lambda,\text{h})\)--gravitational acceleration at the measuring point  
g\({}_{\text{n}}(\varphi)\)--normal field calculated according to [PERSON]'s formula  
R\({}_{\text{F}}(\varphi,\text{h})\)--Fay correction (reduction) for the calculation point at the height h above the ellipsoid when considering the Taylor expansion to the second stage with the consideration of geometric flattening [31]  
g\({}_{\text{g}s}(\text{h})\)--the gravity of a spherical plate with an outer radius of 166.7 km  
T(\(\varphi,\lambda,\text{h})\)--topographic corrections calculated up to 166.7 km from the point calculation