Paleomagnetic evidence for mineralizing fluid flow events in the Uragen super-large Pb-Zn deposit, Wuqia County, Xinjiang, Northwest China

Widespread chemical remagnetization may preserve signatures of paleofluid migration, yet decoding these signals into high-resolution tracers remains challenging. Focusing on the southern Uragen Pb-Zn belt in Wuqia County, Xinjiang, Northwest China, this study integrated thermal demagnetization, rock magnetism, and paleomagnetism to isolate two remagnetization components (A and B) and trace multi-stage fluid events and possible migration pathways. The results reveal that Component A yielded a mean direction of Ds = 5.8°, Is = 59.9° (κ = 173, α95 = 2.4°), corresponding to a paleopole at 85.4°N, 149.1°E. This component records a late Eocene (ca. 40–35 Ma) hydrocarbon-brine charge and alteration event. Component B yielded a mean direction of Ds = 9.3°, Is = 62.3° (κ = 379.3, α95 = 2.2°), with a corresponding paleopole at 82.0°N, 132.5°E, indicating fluid activity during the late stage of main mineralization and diagenesis in the early to middle Eocene (ca. 50–45 Ma). Triggered by the far-field effects of the India–Eurasia collision, deep-reducing fluids migrated upward along reactivated faults and laterally through highly permeable sandstones. These fluids reduced Fe3+ in oxidized red beds, precipitating fine-grained secondary magnetite and causing widespread remagnetization. Furthermore, by utilizing the spatial gradient in Component A’s relative abundance as a proxy, we traced hydrothermal fluid pathways. A distinct attenuation gradient reveals that basinal hydrocarbon brines upwelled from the deep southwest and migrated progressively northeastward within Kezilesu Group reservoirs. These results suggest a fluid migration regime likely dominated by stratabound lateral flow and episodic vertical transport along faults. Elevating remagnetization from solely a chronological marker to a spatial fluid tracer, this study offers a novel approach for tracking deep-seated fluids in sedimentary basins and evaluating concealed fluid pathways potentially related to mineralization.