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Abstract

The investigation of marine, hydrothermal systems requires the integration of multi-disciplinary approaches from e.g. biology, geochemistry, geodynamics, mineralogy and geophysics. Scientific research interfaces closely with economic and environmental interests, for which conflicts seem inevitable since exploration and potential exploitation of seafloor massive sulfides may pose a hazard to all biological activity surrounding hydrothermally active systems. Past investigations have almost exclusively focused on identifying active hydrothermal sites due to the applied technologies: the discovery of sites of interests frequently relied on the detection of temperature or chemical anomalies in the water column, or the identification of characteristic, morphological structures like edifices on the seafloor. In contrast, very little is known about systems where activity has either ceased, is to low to be detected in the water column, or is shielded by sufficiently thick layers of sediment. For such inactive, extinct or buried systems, the use of electromagnetic methods can shed new insights. The sensitivity of electromagnetics towards conductive structures formed by the precipitated minerals is independent of the grade of hydrothermal activity and is able to see through potentially covering sediment layers, thus, providing a valuable constrain to the spatial extents of mineralizations. At GEOMAR, we have built and applied electromagnetic instrumentation to investigate active and inactive hydrothermal sites in the Mediterranean Sea and at the Mid-Atlantic Ridge. Interpretations in some regions show hidden conductive anomalies in areas without current hydrothermal or relevant biological activity, which could be of interest for research exploration without the potential conflict with environmental sciences.