## 5 Results
### Aeromagnetic & Airborne Gravity Interpretation
#### 5.1.2 Airborne Gravity Interpretation  
The interpretation of airborne gravity data is centered on the depth domain (Z) tensor. This include Tz (low frequency), Tzz (high frequency), Txz and Tyz tensors for the analysis of horizontal vectors of the depth domain and Contact Linearant Processed (CLP). Tz gravity anomaly map detects larger subsurface (long wavelength) structure that usually lies deeper and is comparable with the first derivatives of TMI_RTE data that detects shallower magnetic bodies. Tzz responses are prone to the shallower section of the subsurface (short wavelength) while Txz and Tyz focuses on short to intermediate wavelengths. Positive gravity anomalies are captured at the southwest of the coverage area on both Tz and Tzz components that are interpreted as elevated structure which also appear in the shallower section (arrow in Figure 8A,D). Negative (low) gravity anomalies on low and high frequency data are seen in the northeast, central, and southeast regions of the survey area, with a higher concentration in the vicinity of Lada Hitam-1, F6-6 and F19-1 wells. An obvious circular structure within low gravity anomaly (arrow in Figure 8A,D) is recognized on Tz and Tzz data. Anomalies maps of low (Tz) and high ((Tzz) frequency gravity anomalies represent the gravity anomalies for shallow and deep subsurface. Structural trends in the shallower section are dominated by NW-SE orientation (Figure 8C). The Tz gravity map shows a dominant NE-SW structural trend data (Figure 8F), while still preserving the NW-SE trend that seen also on the Tzz data. A minor E-W trend is also observed on the Tz data (Figure 8F). Generally, the structural trends interpreted on Tz and Tzz gravity data give a similar dominant trend NW-SE, suggesting a form of consistency in the basement fabrics at depth <5 km, whereas NE-SW and E-W structural trends appear in the deeper section (Tz). Anomaly maps generated for the horizontal components of gravity data (Txz & Tyz) are dominated by positive anomalies ranging from 0 MGal to 10 MGal. The negative gravity anomalies are scattered in between the positive gravity anomalies from 0 Mgal to \(-\)8 MGal. The Txz signal is dominated by a NW-SE orientation with a prominent NNW-SSE  
Figure 8: Anomaly map for FTG Tzz (high frequency) data; (**A**) Anomaly map for FTG_Tz. (**B**) Interpretation of structural trends on FTG_Tzz. (**C**) Rose plot diagram for FTG_Tzz showing dominant orientation in NW-SE direction. (**D**) Anomaly map for FTG_Tz (low frequency) data; (**E**) Interpretation of structural trends on FTF_Tz. (**F**) Rose plot diagram for FTG_Tz showing orientations in WNW-SE and NE-SW with minor NW-SE. direction. This can be seen from the distribution of the positive and low gravity anomalies distribution on Figure 9A where the positive gravity anomalies (usually representing high relief structures) are aligned in NW-SE to NNW-SSE directions. Structural trend interpreted on Tyz map also preserved NW-SE to E-W directions (Figure 9F). From the gravity anomaly map of Tyz, the northeast side of the survey area (highlighted in dash rectangle on Figure 9D) shows majority of E-W trend while the southern part of the survey area is occupied by NW-SE trend. Both NW-SE to NNW-SSE orientations follow similar trend as interpreted on the Tzz (Figure 8C). The presence of a N-S trend on Txz and E-W trend on Tyz anomalies maps appear to represent the horizontal X and Y components. The analysis of Contact Lineament Processing (CLP) is effective to visualize geological trends at variable depths by application of frequency slicing on the Tz (low frequency, long wavelength) data. Contact lineament filter was applied on several slices based on the 3 wavelengths' ranges, which are (i) 5 to 20 km (short), (ii) 20 to 50 km (medium) and (iii) 50-110 km (long) (Figure 10). Each wavelengths' range is estimated to represent depth half of the wavelengths, based on the assumption of velocity of the rock's composition at 2000 m/s, slightly higher than the water velocity at 1500 m/s.