289-10 Constraints of Spatial Distribution of Ore-Bearing Magmatic Fluids on Copper-Polymetallic Mineralization: Evidence from Integrated Magnetotelluric and Magnetic Surveys in the Eastern Margin of the Altai Mountains, Northwest China

Session: Estimating Natural Resources Using Geoscience Data

Presenting Author:

RONGHUI XUE

Authors:

XUE, RONGHUI¹, YAN, JIAYONG², BAO, ZHONGYI³, DENG, ZHEN⁴, QI, GUANG⁵, TANG, HEJUN⁶

(1) Chinese Academy of Geologi­cal Sciences, Chinese Academy of Geologi­cal Sciences, BEIJING, BEIJING, China, (2) Chinese Academy of Geologi­cal Sciences, Chinese Academy of Geologi­cal Sciences, Beijing, Beijing, China, (3) NO.6 GEOLOGICAL TEAM OF SHANDONG PROVINCIAL BUREAU OF GEOLOGY AND MINERAL RESOURCES, WEIHAI, China, (4) Chinese Academy of Geologi­cal Sciences, Chinese Academy of Geologi­cal Sciences, BEIJING, BEIJING, China, (5) Chinese Academy of Geologi­cal Sciences, Chinese Academy of Geologi­cal Sciences, BEIJING, BEIJING, China, (6) Chinese Academy of Geologi­cal Sciences, Chinese Academy of Geologi­cal Sciences, BEIJING, BEIJING, China,

Abstract:

Mineralization processes associated with magmatic activities exhibit distinct geological and geophysical anomaly characteristics. Magmatism plays a critical role in ore formation by generating thermal energy, transporting metallic elements, and creating favorable structural traps. Magma chambers act as primary sources of mineralizing fluids enriched with metals and volatiles. These fluids migrate through crustal fractures or volcanic conduits ultimately precipitating minerals in structurally favorable zones.   To exploit these features, this study employed integrated magnetotelluric (MT) and magnetic surveys across a 35 km² area in the Naomaohu region of eastern Xinjiang, China—a region with documented magmatic activity and mineralization potential. The MT method, sensitive to subsurface resistivity variations, and magnetic surveys, responsive to magnetic susceptibility differences, were combined to map deep structures and shallow anomalies simultaneously. Data processing included noise reduction, dimensionality analysis, and 3D inversion to enhance resolution.   Analysis of the magnetic survey results revealed critical insights into magmatic pathways. After applying field separation techniques to eliminate regional background interference, 3D magnetic inversion identified vertical, pipe-like anomalies interpreted as fossil magma conduits. These features, likely formed during the Early Variscan orogeny (approximately 350–320 Ma), align closely with surface-mapped volcanic craters, suggesting a genetic link between deep magmatic systems and surface volcanic edifices. This spatial correlation highlights the importance of integrating surface geological mapping with geophysical data to trace fluid pathways.   Magnetotelluric research further uncovered a layered low-resistivity zone at 1,300–2,500 m depth, characterized by resistivity values approximately 10 times lower than the surrounding bedrock. This anomaly, exhibiting lateral continuity and sharp physical boundaries, is interpreted as a preserved magma chamber or a metasomatized zone enriched with conductive fluids. The significant resistivity contrast suggests either partial melting, hydrothermal alteration, or sulfide mineralization—all critical processes in magmatic-hydrothermal systems. Additionally, the geometry of this low-resistivity body aligns spatially with the inferred magma conduits, forming a coherent magmatic network that connects deep reservoirs to shallow mineralization sites.   Combined, these findings demonstrate the utility of multi-method geophysics in unraveling magmatic systems. When cross-referenced with surface geochemical anomalies and alteration patterns, such geophysical frameworks significantly Improved the possibility of deep exploration target recognition. Future work could incorporate seismic surveys or drilling to validate these interpretations, advancing both academic understanding and practical resource discovery in similar magmatic terrains.  

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4600

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