On February 21, the national key scientific and technological project "Deep Earth," under the sub-project titled "Positioning Mechanism and Prospecting Breakthrough of Tin-Antimony-Gold Deposits in the Yunnan-Guizhou-Guangxi Border Region," was officially launched. Xiao Changhao, an expert in ore-field tectonics from the Institute of Geomechanics, is the lead researcher for the project "Discovery of a New Type of Tungsten-Tin Deposit in a New Stratum in the Youjiang Region of Western Guangxi," which was listed among the "Top Ten Geological Science and Technology Advances of 2024" by the China Geological Survey.
Since 2016, Xiao Changhao has been leading geological survey sub-projects focused on the Nandan-Binyang metallogenic belt, conducting tectonic investigations and prospecting predictions. Through mapping three geological sections and dissecting typical deposits, he proposed new insights into structural ore control. For the first time, he identified and discovered a paleokarst-hosted tin deposit at Bawang, west of the Wuxu ore field.
The research team developed a structural ore-control model applicable to the entire Youjiang Basin, identifying a new type of tin deposit. They systematically summarized the structural ore-control patterns of magmatic-hydrothermal tin deposits in the Youjiang region, overturning previous understandings of mineralization and ore control. The team revealed new mechanisms for tin migration and cassiterite precipitation in hydrothermal fluids, emphasizing that focused fluid flow guided by structural pathways is a critical prerequisite for tin mineralization. They proposed that superimposed zones of deep concealed intrusions and structurally weak zones formed by sedimentary phase transitions are prospective areas for exploration, with major deep faults serving as favorable ore-conducting structures and interlayer fracture zones as key ore-hosting spaces. Additionally, they established a fracture and fold-related longitudinal tension joint control model for muscovite-quartz vein-type tungsten-tin deposits hosted in clastic rocks, linked to late Yanshanian magmatism, and formulated a regional tectonic ore-control model of "deep magmatic supply, vertical structural migration, and lateral infilling replacement."
Can this new structural ore-control model from the Danchi metallogenic belt lead to the discovery of the next Danchang ore field? Is it applicable to the vast Triassic clastic sedimentary rock regions of the Youjiang Basin? Through an in-depth analysis of the 1:200,000 mineral geological map and related data from western Guangxi, the project team initially concluded that the Tangxing-Liudan area in the Youjiang district of Baise, Guangxi, fully matches the model’s characteristics.
Since 2019, supported by China Geological Survey projects such as "Tectonic Investigation and Prospecting Prediction of the Tin-Polymetallic Ore Cluster in the Youjiang Metallogenic Belt," "Strategic Mineral Investigation and Evaluation of Tin-Antimony-Gold Polymetallic Deposits in the Youjiang Region," and "Structural Ore-Control Investigation of Strategic Minerals in Key Metallogenic Belts," as well as various local fiscal projects, Xiao Changhao’s team has shifted their focus from the Danchi metallogenic belt westward to the Baise region. They have concentrated most of their efforts on tin exploration in the Tangxing-Liudan area.
Years of persistent and systematic research have finally yielded results. Through detailed surveys and in-depth studies, Xiao’s team concluded that tin mineralization occurs in an extensional/strike-slip tectonic environment. In the Youjiang region, Cretaceous basin-scale extensional tectonics provided the favorable structural setting for tin mineralization, with variations in tectonic styles controlling the spatial differentiation of tin and tungsten.
For the first time, a new type of tungsten-tin deposit was uncovered in a new stratigraphic horizon within the basin interior. This is the Pingna tungsten-tin deposit in Baise, Guangxi, controlled by secondary faults of northwest-trending strike-slip systems. The Pingna deposit represents the first late Cretaceous tungsten-tin deposit discovered in the thick sedimentary cover of the Youjiang Basin interior and the first hydrothermal vein-type tungsten-tin deposit found in Triassic clastic rocks, offering dual theoretical and practical significance. The discovery of the Pingna deposit provides critical theoretical and empirical support for tungsten-tin exploration in Guangxi and nationwide.
Since September 2024, Xiao Changhao has led the second-level project "National Key Metallogenic Belt Ore-Control Investigation," implementing a deep borehole in Pingna, Baise. The drilling, currently at a depth of 1,500 meters, has successfully intersected tungsten-tin ore bodies. Above 725 meters, 20 industrial-grade tungsten ore layers have been identified, with a cumulative true thickness exceeding 30 meters. The tungsten deposit is projected to reach large-scale status. These findings were recognized by leaders from the Guangxi Natural Resources Department and the Guangxi Bureau of Geology and Mineral Resources during a delegated business review on November 30, affirming that the Youjiang-Tianlin tungsten-tin key investigation area in western Guangxi meets the criteria to be upgraded to a key exploration zone. It has the potential to become a major tungsten-tin resource base following the "Nandan Tin-Antimony Polymetallic Large-Scale Resource Base in Hechi, Guangxi," marking a significant milestone in the new round of tungsten-tin prospecting breakthroughs in western Guangxi.
Xiao Changhao noted that since 2020, his team has completed five boreholes totaling over 4,000 meters, all intersecting tungsten-tin ore bodies, achieving a 100% success rate. The discovery of two new tungsten-tin deposits has added a potential economic value of 3.5 billion yuan. Inspired by these results, Guangxi’s natural resources management authorities and geological exploration teams have incorporated the new concept of "exploration for high-temperature hydrothermal deposits related to concealed intrusions" into the region’s strategic action plan for a new round of prospecting breakthroughs. The "Geological Exploration Plan of Guangxi Zhuang Autonomous Region (2022–2035)" designates the "Pingna Tin-Polymetallic Ore District in the Youjiang Region" as a key exploration area moving forward. This has prompted an initial investment of 12.5 million yuan from the autonomous region’s budget for 2024–2025 to implement the "Guangxi Youjiang Pingna Ore District Tin-Tungsten Reconnaissance" project, with plans to further intensify exploration efforts during the "15th Five-Year Plan" period.
Source: iNature
