Onshore to offshore correlation of ore-forming hydrothermal systems: Geological investigations of the Reinfjord Ultramafic Complex and Southwestern Barents Sea

Abstract

Demand for mineral resources continues to grow, while political pressure, legitimate environmental concerns, and important ethical questions slow the development of new mineral resources. Simultaneously, emerging technologies promise to open new frontiers, and exploration into subsea mineral resources has been rapidly expanding. While Mid Ocean Ridges and other deep-sea deposits receive significant attention, fewer researchers have investigated near shore continental shelves. These domains are a continuation of onshore continental landmass, and as such are likely to contain similar resources those extracted on land today, in a setting possibly mitigating some environmental and ethical concerns. We consider the onshore - offshore correlation of ore-forming hydrothermal system and their presence on the Norwegian continental shelf, exploring various aspects of such hydrothermal systems at a variety of crustal depths. The roots of hydrothermal systems can extend to great depths, with mantle isotope signatures commonly found in both mineral and hydrocarbon resources. We investigate structures at a variety of depths, from the lower crustal domain in the Reinfjord Ultramafic Complex to near-surface basins in the Barents Sea and exhumed continental crust on Bj0rn0ya, documenting the role hydrothermal fluids play in each setting. Finally, we extrapolate our knowledge from an onshore hydrothermal system to the offshore domain, correlating grand-scale structures and regional geology to relate Pb - Zn mineralizations on Bj0rn0ya to Pb - Zn mineralizations on the Lappa High. Our studies incorporate regional geophysical surveys, including potential field and seismic data, with field studies, sampling, fluid inclusion analysis, electron backscatter diffraction, electron microprobe analysis and more to create a detailed description of each field area. Hydrothermal fluids play a major role in deformation at all crustal depths, enabling both shear and seismicity along lower crustal faults, and promoting faulting in shallow basinal settings. By investigating fluids and the structures along which the flow, we gain a better understanding of deformation processes at both lower and upper crustal depths. Finally, the grand-scale structures along which fluids flow allow us to trace mineralized hydrothermal systems from the onshore to the offshore domain, opening new frontiers in exploration geology.