3D geological modeling of the Julong'an uranium deposit in Jiangxi Province and implications for deep geological feature analysis

The Julong'an deposit is a large volcanic rock type uranium deposit located in the western part of the Xiangshan uranium ore field in Fuzhou City, Jiangxi Province. This study comprehensively utilized topographic maps, geological maps of mineral deposits, 26 exploration line profiles, 5 mid section plans, 65 drill holes etc. Using the “show-hide” interactive 3D geological modeling method, a 3D geological model of the Julong'an uranium deposit was constructed based on GOCAD software (Figure 1). Through 3D modeling, the following deep geological features were revealed:

• The second memberof the Ehuling Formation is thin in the north and thick in the south, with an exposed elevation of -610 to + Between profile lines 68 and 74, the bottom interface rises sharply from south to north, with a drop of 893m, and the north-south profile is in an "S" shape.
• The second memberof the Daguding Formation is thick in the north and thin in the south, with an exposed elevation of -700 to + Between lines 68 and 74, the thickness of the rhyolitic dacite increases sharply from an average of 15m to over 764m, and within a range of 240m from north to south, the thickness increases by over 749m. The top interface drops by more than 768m, forming an east-west "lava waterfall distribution".
• The fault structures mainly include the nearly north-south F7 fault, a hidden fault, and the east-west Niutoushan-Julong'an-Chuankeng volcanic collapse structure. The hidden fault is located on the west side of F7, and the two merge to the north with a gradually widening distance to the south. The cutting depth gradually becomes shallower from north to south. The shallow part of the F7 fault is a steeply dipping main fracture zone, while the deep part gradually transitions into a gently dipping crack dense zone. The fracture appears in an "Open fork" shape on the east-west cross-section and in an inverted "Open fork" shape on the horizontal cross-section (Figure 2). When the fissure zone approaches the intersection of different geological interfaces, mineralization significantly increases, forming a dense vein ore bodies. In the diamond shaped block of Julong'an, other nearly north-south and eastward dipping faults have similar characteristics and mineralization patterns. So, deep mineral exploration should focus on the intersection of the fracture zones of north-south faults and the interfaces between volcanic rock formations, angle unconformities, and intrusion interfaces, especially in the composite areas of east-west volcanic collapse structures on the southern part, which are key target areas for searching for large and rich minerals.

Funding: National Natural Science Foundation of China (42472130), ECUT Research Development Fund (K20240018), and the Natural Science Foundation of Jiangxi Province (20242BAB25183).