Isochron Map
​
Thickness maps are a fundamental tool in structural geology. They represent thickness variations and thickness trends of a given unit. One of the important types of thickness maps is Isochore map, which is a map that connects points of equal vertical thickness between two horizon surfaces. According to the seismic section, three thickness maps are implemented based on two neighboring horizons. (Refer to figure 1)
Figure 1: Thickness maps for all relative surface horizons
For the surface thickness between horizon 1 and 2, the data given shows that the overall thickness is relatively close as it ranges from 120 m to 300 m. The purple color indicates minimum vertical thicknes, whilst red shows maximum value, as shown in the legend. This says that facies 1 is almost a flat surface with a slight bulge at the center of the cross section.
In contrary with the other thickness maps, surface thickness between horizon 2 and 3, and surface thickness between horizon 3 and 4 representing facies 2 and facies 3, respectively, both have significant lateral differences in depth. This is because of the anticline observed in the lower part of the section. As depicted from figure 2, facies 2 left flank on the southern direction dips more than the right flank on the northern direction. As a result, the left flank is thicker compared to the right flank.
​Figure 2: surface thickness between horizon 2 and 3
In facies 3, the right flank on the northern direction dips more than the left flank on the southern direction as illustrated in figure 3. The thickest sediment is shown in yellow and orange (800 m - 900 m), moderate sediment thickness shown in light blue and green color ( 550 m – 750 m) while the thinner sediment represent in purple and blue color (400 m – 500 m) Therefore, the right flank is thicker compared to the left flank.
​
The major reason for facies 2 and facies 3 to have thinner sediments in the center is because of the formation of the anticline structure, while it is assumed that the position of the major faults may have played a role to the dipping angle of the fold and the distribution of the sediments.
Figure 3: surface thickness between horizon 3 and 4