Application of automated structural extraction algorithm in Heiqia iron polymetallic mineralization zone

The study area is located at the Heiqiadaban Pass, east of Mazar in Xinjiang Uygur Autonomous Region (Figure 1). The area boasts well-developed strata, complex tectonic activity, diverse metamorphic processes, and frequent magmatic activity, resulting in extremely favorable mineralization conditions. Abundant mineral deposits have been discovered, encompassing both metallic and non-metallic minerals, with a complete range of mineral types, good resource endowment, and broad exploration prospects. However, the area has an average elevation exceeding 4600 m, rugged terrain, sparse population, and extremely inconvenient transportation, severely restricting geological survey work. Therefore, hyperspectral satellite remote sensing technology was used to extract tectonic information from the study area, identify tectonically dominant favorable mineralization areas, aid in planning exploration routes, and increase exploration efficiency.

Existing remote sensing studies indicate that rich ore bodies are mostly hosted at the intersection of NW-trending mineralization zones and NE-trending faults (cited from Yang Jinzhong et al., 2017). Therefore, this study aims to employ an automated structural extraction algorithm to identify the intersection nodes of structures with different orientations within the area, providing a basis for delineating favorable mineralization target areas.

Figure 1. Remote sensing image of the study area

Heiqiadaban is located at the intersection of the West Kunlun Orogenic Belt, the North Qiangtang-Sanjiang Orogenic Belt and the Bayan Har Orogenic Belt (Figure 2). Its tectonic boundary is controlled by the Mazha-Kangxiwa tectonic belt: it is adjacent to the Kunnan Block to the north, the Tianshuihai Block to the southwest, and the Bayan Har Block to the southeast (cited from Yang Chen et al., 2018).

Figure 2. Simplified geological map of the study area (from Fan Yuhai, 2022)

The study area, from north to south, encompasses two major metallogenic domains—Qinqikun and Tethyan—three second-order metallogenic units (Kunlun, Bayan Har-Songpan, and Karakoram-Sanjiang), four third-order metallogenic units, and four fourth-order metallogenic units (Figure 3 and Table 1). The Heiqia iron polymetallic mineralization belt is located on the northern margin of the fourth-order Fe-Cu-Au-Pb-Zn-RM mineralization belt (III1-①) in the Muztagh-Aksai Chin (continental margin basin) (cited from Wang et al., 2016).

Figure 3. Schematic diagram of mineralization zone (area) division in the study area.

(Quoted from Wang Hui et al., 2016)

Table 1. Mineralization zone (area) division of the study area (cited from Wang Hui et al., 2016)

This study first extracts the spatial distribution information of Fe³⁺ (trivalent iron) ions in the study area based on remote sensing data, and then determines the boundary of the polymetallic mineralization zone based on the linear distribution characteristics of the Fe³⁺ enrichment area (Figure 4).

Figure 4. Fe3+ distribution map and Heiqia polymetallic mineralization zone in the study area.

The mineralization zone appears as a distinct tonal anomalous band in RGB composite satellite imagery (Figure 5).

Figure 5. Black Chaga polymetallic mineralization zone

Based on this, satellite imagery was input into an automated structural extraction algorithm for linear structural interpretation. The algorithm automatically acquired the spatial distribution pattern of fault structures in the study area and marked the points where structural strike changes occurred (Figure 6). Statistical analysis identified a total of 6 structural strike change nodes, of which 4 are located in the favorable polymetallic mineralization area of ​​Heiqia in the middle of Figure 7, 1 is located in the favorable lead-zinc polymetallic mineralization area north of Heiqia Daban in the upper left of Figure 7, and another is located in the favorable tungsten-lead-zinc and jade mineralization area north of Hepingqiao in the upper right. The above-mentioned structural intersections have a good spatial coupling relationship with known mineralization zones, indicating favorable metallogenic geological conditions.

Figure 6. Tectonic distribution and trend changes in the study area

Figure 7. Mineral exploration prediction map of the study area (from Fan et al., 2022)

References

Yang Chen, Wang Hui, Zhang Shaopeng, et al. Evaluation of mineral resource potential in the Heiqia-Sanliyingfang area of ​​West Kunlun Mountains [J]. Geological Survey of China, 2018, 5(6):33-40.

Fan, Yuhai. Comprehensive Study on Geophysical and Geochemical Anomalies in the Heiqia Area of ​​the West Kunlun Orogenic Belt and Prediction of Favorable Mineral Exploration Areas (Location and Quantity) [D]. Chang'an University, 2022.

Wang Hui, Fan Yuhai, Zhang Shaopeng, et al. Delineation of the Heiqia iron polymetallic mineralization zone in the West Kunlun Mountains using high-resolution remote sensing technology [J]. Geological Survey of China, 2016, 3(5):13-20.

Yang Jinzhong, Chen Wei, Wang Hui. Delineation of iron-bearing strata in the Heiqiadaban Wenquangou Group of the West Kunlun metallogenic belt [J]. Remote Sensing of Land and Resources, 2017, 29(3):191-195.