# Methodology and Results of Detailed 3D Seismic Exploration in the Zhezkazgan Ore District
## 3 Results  
In general, the seismic data clearly outline the composite structure of geological boundaries across the entire area of each section, especially in the upper inter-well section which cannot be assessed using well drilling data. The seismic wave field within the target interval at 0-200 ms is characterized by the composite nature of the reflections, apparently due to the shortcomings of the field data acquisition technique (the reflection events are discontinuous; the correlation of reflecting boundaries is complicated by interference between different seismic waves), which, un  
Figure 6: Examples of attribute analysis maps. Explanation is given in the text. fortunately, could not be attenuated during seismic data processing, thus excluding the possibility of definite correlation of the reflectors in this time interval. The seismic wave field of the reflection complex at the values exceeding 180-200 ms differs sharply from the wave pattern associated with upper sediments. The reflecting boundaries were well traced and the wave pattern is represented by a sequence of reflections showing conformable occurrence at depths greater than 300 m. The presence of reflections on time sections is completely determined by the behavior of reflecting boundaries, characterized by dynamic expression and traceability within the entire study area. To a lesser extent, the poor quality of seismic data is associated with dipping events which do not exceed 10-12\({}^{\circ}\) within the study area, as well as with the heterogeneity of velocity properties of the upper part of the section studied during the uphole survey. Analysis of the wave field of the time migration cube by target horizons showed a good correlation between amplitudes and geological data. Comparing the geological map of the Pektas site and slices of the time-migrated data volume (PSTM), it was found that linear forms of amplitude anomalies of seismic exploration coincided with submeridional geological sediments (Figure 7). The seismic lines coinciding with coordinates of geological sections together with existing well information were extracted from the seismic data. The reflectors and geological boundaries were included based on the changes in lithology of the boreholes marked on seismic lines and velocity laws obtained during data processing. Depth seismic data were obtained at the Donyzauz site after pre-stack depth migration (PSDM) and were used for separate correlation of the outlined horizons 1 (top of Taskuduk horizon), 1-I, 1-II, and 1-III (ore deposit, cut-off grade lead ores), 1-b (top of Zhilandy horizon), and 1-v (top of Kopkuduk horizon). Moreover, according to the depth migration data, the flexures that occurred in the seismic wave field were used for delineation of three lens-shaped targets in cross section in the vicinity of the boreholes and in the intervals of ore occurrence. The targets were conventionally named Target-I, Target-II, and Target-III (Figure 8). Figure 7: Pektas area. Comparison of PSTM time slice and geologic map. The image of the geological section built according to drilling data shows that the geological sediments along seismic line 87 are synclinal with a sharp increase in the angles of incidence in stratigraphic sequences at the edges of the area being studied. However, seismic exploration data show more flat bedding for shallow horizons (20-22\({}^{\circ}\)), as well as a block structure of the section with tectonic elements. The sections (inlines--sections along receiver lines, and crosslines--sections along shot lines) show a qualitative picture of the seismic wave field used to delineate fault zones and fracturing areas [40]. Such zones can potentially be confined to hydrothermal sources (channels), which fed the ore bodies in the past. The seismic section along geological profile XXXII of the Pektas site clearly shows the presence of deep faults, which are apparently the channels of intrusion of ore solutions from deep magmatic centers to overlying layers (Figure 9).