ABSTRACT Ore deposits are formed by a variety of processes, and mineralised host rocks possess unusual petrophysical properties in contrast to un-mineralised country rock. Mineralised systems can therefore be identified directly in geophysical data via anomalous geophysical responses. In this paper, we review the interpretation of geology from aeromagnetic and electromagnetic data relative to orogenic gold systems. As a case study, we examine the Hyde-Macraes Shear Zone in eastern Otago, New Zealand, which hosts a world-class orogenic gold system within hydrothermally altered and graphitic schist. A subtle low-resistivity anomaly in electromagnetic data correlates well with the location of the mineralised shear zone, which is otherwise indistinct in aeromagnetic data. We interpret other candidates for mineralised structures to be present in similar low-resistivity features in the south of the study area. We interpret magnetite-bearing mafic bodies, and magnetite- and pyrrhotite-rich schists to be the source of regionally extensive, isoclinally folded anomalies which are prominent features in the magnetic and electrical data and allude to the complex accretion and deformation history of the Otago Schist. Future work encompassing detailed field analyses of low-resistivity anomalies in the south of the map may reveal suitable targets for exploration.

中文翻译：

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从多变形和矿化地体的地球物理学解释地质学；奥塔哥片岩和海德-马克莱斯剪切带

摘要 矿床是由多种过程形成的，与未矿化的围岩相比，矿化的围岩具有不同寻常的岩石物理特性。因此，可以通过异常地球物理响应直接在地球物理数据中识别矿化系统。在本文中，我们回顾了从与造山金系统相关的航磁和电磁数据对地质的解释。作为案例研究，我们研究了新西兰奥塔哥东部的海德-麦克雷斯剪切带，该带在热液蚀变和石墨片岩中拥有世界级的造山金系统。电磁数据中一个微妙的低电阻率异常与矿化剪切带的位置密切相关，否则在航磁数据中是模糊的。我们将其他矿化结构的候选物解释为存在于研究区南部类似的低电阻率特征中。我们将含磁铁矿的基性体和富含磁铁矿和磁黄铁矿的片岩解释为区域广泛的等斜折叠异常的来源，这些异常是磁和电数据中的突出特征，并暗示奥塔哥片岩复杂的吸积和变形历史. 未来的工作包括对地图南部低电阻率异常的详细现场分析，可能会揭示合适的勘探目标。等斜折叠异常是磁电数据中的突出特征，暗示了奥塔哥片岩复杂的吸积和变形历史。未来的工作包括对地图南部低电阻率异常的详细现场分析，可能会揭示合适的勘探目标。等斜折叠异常是磁电数据中的突出特征，暗示了奥塔哥片岩复杂的吸积和变形历史。未来的工作包括对地图南部低电阻率异常的详细现场分析，可能会揭示合适的勘探目标。