Abstract
Loki’s Castle on the Arctic Mid-Ocean Ridge (AMOR) is an area of possible seafloor massive sulphide (SMS)-style mineralisation under Norwegian jurisdiction, which, due to mounting social pressure, may be a strategic future source of base and precious metals. The purpose of this study is to characterise mineralised material from a hydrothermal vent system on the AMOR in detail for the first time, and to discuss the suitability of methods used; reflected light microscopy, X-ray diffraction (XRD), whole rock geochemistry, electron probe micro-analysis (EPMA), and QEMSCAN. The primary sulphide phases, identifiable by microscopy, are pyrite and marcasite with minor pyrrhotite and galena, but multiple samples from the Loki’s Castle contain economically interesting quantities of copper (hosted in isocubanite and chalcopyrite) and zinc (hosted in sphalerite), as well as silver and gold. This reinforces the notion that slow spreading ridges may host significant base metal deposits. Micro-textures (chalcopyrite inclusions and exsolutions in sphalerite and isocubanite respectively) are typically undefinable by QEMSCAN, and require quantitative measurement by EPMA. QEMSCAN can be used to efficiently generate average grain size and mineral association data, as well as composition data, and is likely to be a powerful tool in assessing the effectiveness of SMS mineral processing.
Highlights
Socio-economic advances in developing countries have led to an increased per capita demand for a variety of mineral and metal types necessary for upgrading infrastructure, technology, and sustainable energy production [1,2]
Total, of loose probable-chimney from thefragments mound flanks recovered as non-in-situ surface more than 200 kg of loose fragments probable‐chimney fromwere the mound flanks were recovered as grab samples by a video-guided remotely operated vehicle (ROV)-mounted hydraulic manipulator
The results suggest that a 1 μm step size is superior to 10 μm, but realistically, this is still not high enough for characterisation of the Cu-sulphide phases in this case
Summary
Socio-economic advances in developing countries have led to an increased per capita demand for a variety of mineral and metal types necessary for upgrading infrastructure, technology, and sustainable energy production [1,2]. Recent deep sea research has identified a potential new source for a variety of critical metals, including copper, zinc, silver, and gold, from seafloor massive sulphides (SMS) [3,4,5]. These SMS deposits are present on the seafloor as active or inactive hydrothermal vent systems, and they may represent contemporary analogues of volcanogenic massive sulphide (VMS) deposits, a classic and long utilised source of base and precious metals [6].
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