Searching for mineral traces in desert mountains

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The northwestern part of our country has a continental arid climate. From the edge of the desert outward, there are successively alluvial-pluvial silty plains (desert), glacial-pluvial gravel fan areas (gobi), and wind-eroded hills and mountains. Wind-eroded hills and mountains are characterized by exposed sand, gravel, and rocks, with little vegetation, which is why they are called desert mountain areas. In the desert mountainous areas, everything appears completely exposed – the rocks, structures, alterations, and mineralizations are all visible, making prospecting very easy. Some even say that satellite remote sensing images can quickly identify mineral deposits, and those colorful remote sensing interpretation maps have also captivated many laypeople. That’s not the case. Indeed, the windward side of the Desert Mountain area is completely exposed; there is no cover whatsoever for surface alteration or mineralization, allowing everything to be seen clearly. However, such mineralizations have mostly been discovered and exploited by ancient people or their predecessors. However, the leeward side is often buried under wind-blown dust and sand layers several meters to dozens of meters thick, making it difficult to trace any signs of alteration or mineralization. This scene is like a naked, thin man, with his ribs clearly visible on the front, while his back is covered in dirt and sweat, obscuring the color of his skin. Moreover, the valleys are deeply buried by colluvial glacial deposits, and the mountaintops are mostly covered with yellow sand. This results in intermittent rock outcrops and fragmented information. Due to extreme drought, alternating periods of intense sunlight and cold, strong winds, weak chemical weathering, and strong physical weathering, the apparent characteristics of the exposed rocks differ greatly from their true nature. There are three manifestations of this: First, color convergence: Different rocks that originally had large color differences become dark, smooth, and shiny on their surfaces due to exposure to sunlight and wind erosion. If a geological hammer is not used to strike continuously along the way, many types of rocks will be missed or misidentified. Secondly, the occurrence pattern is difficult to discern: due to large temperature differences between day and night, causing expansion when hot and contraction when cold, fractures often occur vertically along the ground surface; under the force of strong monsoons, they tilt towards the leeward side. Without using trenching to expose them, it is difficult to determine the rock types and the orientation of faults. Thirdly, metal oxides are difficult to find: sometimes, due to excessive leaching caused by drought, the elemental anomalies in the altered and mineralized zones are not obvious, or even show negative anomalies. After the rain and snow, the metal oxides that formed on the surface of the rocks were blown away by wind and sand, leaving only hollow spaces behind; it creates an atmosphere reminiscent of the line \"The people of old have gone away on the yellow crane; only the Yellow Crane Tower remains here. Once the yellow crane has left, it never returns, while the white clouds drift on endlessly for thousands of years.\" The desertous mountain terrain of this unique landscape results in poor effectiveness of some common mineral exploration methods. Due to weak chemical weathering, dust accumulates, and conventional soil geochemistry is ineffective ； The development of glacial slope deposits and wind-blown dust results in poor geochemistry of the water system sediments ； Due to excessive dust and dirt, the electrode has poor grounding performance ； Conventional electrical methods yield poor results due to salt crusts, shifting sand layers, etc. Finding traces of mineralization in those seemingly bare desert mountains is not as easy as one might think! The true nature of some desert mountain areas that appear to have a high degree of human activity is not well understood. So, what are good ways to search for traces of mineralization in desert mountains? What should be done? 1. If there is no geological map, first create a remote sensing interpretation map, then conduct on-site verification to prepare the geological map. Preparing geological maps is a fundamental task necessary for mineral exploration. Large-scale geological maps must be drawn in the field; remote sensing interpretation is ineffective for this purpose. 2. If a geological map is available, no remotely sensed interpretation map at the same scale is prepared. No matter how detailed the remote sensing interpretation is, it cannot compare to a geological map at the same scale. A simple way is to go to Google Earth to view the spatial images of the work area, or use topographic maps to mark the geological structures on the highest peaks. When climbing a mountain, one must reach the summit; if there are cliffs, be sure to observe them. 3. Carry out geological profile observation and sampling work carefully; remember to use a geological hammer to strike repeatedly, and don’t rely on assumptions. Pay attention to identifying characteristic minerals and rocks. 4. Pay attention to areas of cavity development, iron-stained bands, faded bands, and tumbled stones. 5. Select targeted geophysical and geochemical methods. 6. Pay attention to the distribution patterns of dust and sand. If wind-blown dust develops in areas on the mountain slopes where it is not easy for such dust to adhere, then the range and axis direction of the distribution of this wind-blown dust generally correspond to the range and direction of the fractured zones (or mineralized areas). 7. Pay attention to the beach in front of the mountain and imagine what lies beneath it. 8. Think with your mind; gain insights with every observation.