ABSTRACT We evaluated imaging alteration associated with porphyry copper style mineralisation using aeromagnetic data in the Highland Valley Copper (HVC) district as part of the Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Mining Innovation Council (CMIC) Footprints project. The first step of the investigation involved construction of a 3D geological model based on surface and regional information, and petrophysical data of the host rocks. From the petrophysics, it was observed that hydrothermal alteration affected the magnetic susceptibility of some batholithic host rocks at HVC, and low susceptibility values were associated with the altered rocks. From this observation, an alteration index was devised, differencing, based on the magnetic susceptibility, between unaltered and altered batholith host rocks. Three-dimensional inversions were conducted using geological constraints obtained from surface and borehole geology as well as physical property data. Then the alteration index methodology was tested using 3D inversions and residual models within five overlapping blocks covering portions of the batholith. The indices inferred from inverted susceptibility were compared to surface mapped alteration. For some felsic facies of the batholith, the alteration index derived from inverted magnetic susceptibility corresponds to the mapped alteration and delineates the known porphyry Cu system district. However, it is not true for others where alteration was less magnetite-destructive and more focused in structures.

中文翻译：

---

使用加拿大不列颠哥伦比亚省高地谷铜矿的航磁数据对斑岩铜蚀变进行成像

摘要 作为加拿大自然科学和工程研究委员会 (NSERC) 和加拿大矿业创新委员会 (CMIC) 足迹项目的一部分，我们使用高地谷铜 (HVC) 区的航磁数据评估了与斑岩铜型矿化相关的成像变化。调查的第一步涉及基于地表和区域信息以及主岩的岩石物理数据构建 3D 地质模型。从岩石物理学上观察，热液蚀变影响了一些基岩主岩的磁化率，低磁化率值与蚀变岩有关。根据这一观察，设计了一个蚀变指数，根据磁化率，在未蚀变和蚀变的基岩主岩之间进行区分。使用从地表和钻孔地质以及物理性质数据获得的地质约束进行了三维反演。然后在覆盖基岩部分的五个重叠块内使用 3D 反演和残差模型测试蚀变指数方法。将从倒置磁化率推断出的指数与表面映射的变化进行比较。对于基岩的一些长英质相，由倒磁化率得出的蚀变指数对应于绘制的蚀变并描绘了已知的斑岩铜系统区。然而，对于其他对磁铁矿破坏性较小且更集中于结构的蚀变而言，情况并非如此。然后在覆盖基岩部分的五个重叠块内使用 3D 反演和残差模型测试蚀变指数方法。将从反向磁化率推断出的指数与表面映射的变化进行比较。对于基岩的一些长英质相，由倒磁化率得出的蚀变指数对应于绘制的蚀变并描绘了已知的斑岩铜系统区。然而，对于其他对磁铁矿破坏性较小且更集中于结构的蚀变而言，情况并非如此。然后在覆盖基岩部分的五个重叠块内使用 3D 反演和残差模型测试蚀变指数方法。将从反向磁化率推断出的指数与表面映射的变化进行比较。对于基岩的一些长英质相，由倒磁化率得出的蚀变指数对应于绘制的蚀变并描绘了已知的斑岩铜系统区。然而，对于其他对磁铁矿破坏性较小且更集中于结构的蚀变而言，情况并非如此。由倒磁化率得出的蚀变指数对应于绘制的蚀变并描绘了已知的斑岩铜系统区。然而，对于其他对磁铁矿破坏性较小且更集中于结构的蚀变而言，情况并非如此。由倒磁化率得出的蚀变指数对应于绘制的蚀变并描绘了已知的斑岩铜系统区。然而，对于其他对磁铁矿破坏性较小且更集中于结构的蚀变而言，情况并非如此。