Porphyry mineral systems provide a significant source of critical minerals for modern society, that are predominantly formed in subduction related settings from magmatic hydrothermal fluids derived from an underlying reservoir. However, in post-subduction settings the processes that entrain and focus magmatic hydrothermal fluids throughout the crust, from source to deposit are often poorly constrained. In this paper, we have undertaken a magnetotelluric (MT) survey in an intracontinental tectonic setting across the Adelaide Superbasin, which is a Neoproterozoic passive margin formed during rifting of the supercontinent Rodinia. This region contains the Burra magmatic copper deposit, along with numerous sedimentary-hosted copper deposits. Systematic three-dimensional modelling was undertaken, initially at regional-scale, with 55 km gridded long-period AusLAMP data over a 500 × 500 km area, followed by infilled 10 km gridded broadband MT data, at the district-scale, centred over an area of copper deposits in the Adelaide Rift Complex. The modelling reveals an elongated zone of low electrical resistivity (∼100 Ω.m), in an otherwise resistive crust, at lower crustal depth (20–40 km) that is contiguous with the regional lineament of the Adelaide Rift Complex and copper and gold mineralisation. A narrow zone of low resistivity (∼100 Ω.m) branches through the upper crust (5–20 km) to the surface, that is remarkably aligned with the Burra magmatic mineral system, in an otherwise quite resistive crust (∼1000 Ω.m). Additionally, in the upper crust a zone of low resistivity (1–10 Ω.m at a depth of 5–8 km) extends from the Burra magmatic copper deposit southwards, constrained by anticlinal folding from the ∼500 Ma Delamerian Orogenic deformation of the Adelaide Rift Complex and spatially aligned with the Kapunda sedimentary-hosted copper deposit. We argue that the low electrical resistivity signature encapsulates a whole-of-lithosphere magmatically-hosted copper system, that is further mobilised by low-temperature fluids by mapping the footprint of ore-forming fluids from the source to associated mineralisation. Where later basin wide fluid recycling in a permeability enhanced basin, via neo-tectonism along pre-existing structures/trends, has likely remobilised copper, from a prior magmatic event, with copper being leached in chloride-rich saline fluids at low temperatures.

中文翻译：

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澳大利亚阿德莱德裂谷复合体陆内热液矿物系统的多尺度电阻率测绘

斑岩矿物系统为现代社会提供了重要矿物的重要来源，这些矿物主要是在俯冲相关环境中由来自底层储层的岩浆热液流体形成的。然而，在俯冲后环境中，从源头到沉积物在整个地壳中夹带和聚集岩浆热液的过程通常受到很少的限制。在本文中，我们在阿德莱德超级盆地的陆内构造环境中进行了大地电磁（MT）调查，阿德莱德超级盆地是罗迪尼亚超大陆裂谷期间形成的新元古代被动边缘。该地区包含布拉岩浆铜矿床以及众多沉积铜矿床。首先在区域尺度上进行了系统的三维建模，在 500 × 500 km 区域内使用 55 km 网格化长周期 AusLAMP 数据，然后在区级尺度上填充 10 km 网格化宽带 MT 数据。阿德莱德裂谷复合体的铜矿床区域。该模型揭示了在较低地壳深度（20-40 公里）的电阻地壳中存在一个细长的低电阻率区域（∼100 Ω.m），该区域与阿德莱德裂谷复合体的区域轮廓以及铜和金相邻矿化。一个狭窄的低电阻率区域（~100 Ω.m）从上地壳（5-20​​ km）分支到地表，与 Burra 岩浆矿物系统显着对齐，在一个电阻率相当高的地壳（~1000 Ω.m）中。米）。此外，在上地壳中，一个低电阻率区域（深度为 5-8 km 处为 1-10 Ω.m）从 Burra 岩浆铜矿床向南延伸，受到约 500 Ma Delamerian 造山变形产生的背斜褶皱的限制。阿德莱德裂谷复合体在空间上与卡蓬达沉积铜矿床对齐。我们认为，低电阻率特征封装了整个岩石圈岩浆托管的铜系统，通过绘制成矿流体从源头到相关矿化的足迹，低温流体进一步动员了该系统。后来，通过沿着预先存在的结构/趋势的新构造运动，渗透性增强盆地中的盆地范围内的流体循环，很可能从先前的岩浆事件中重新激活了铜，其中铜在低温下浸出在富含氯化物的盐流体中。