Hydrothermal fluid circulation in the oceanic lithosphere is a crucial process for chemical and heat transfer and the basis for unique biological habitats in the deep ocean. Hydrothermal vents can also produce potentially valuable mineral deposits. However, most of our knowledge is restricted to seabed expressions such as black smokers and sulfide mounds; but what is underneath and how much can we learn about the hydrothermal system from geophysical data? This talk will explore how magnetic imaging sheds light to the third dimension of two deep-sea hydrothermal vent sites on the Central Indian Ridge. Natural and active magnetic methods were applied using AUV, ROV and deep-towed vehicles. Our integrated mapping approach combines magnetic and electromagnetic data with bathymetry, photogrammetry, and geochemical and petrophysical characteristics to explore the complex internal structure of active and extinct sulfide deposits. Inverse modelling reveals the electric and magnetic subsurface inventory and supports an evaluation of the mineral resource potential. Deep structures of poor magnetization connect the near-surface deposits with the possible heat source several hundred meters below seafloor. These exemplary results help us to touch advances in sensor technology and integration, geophysical inverse modelling and system operation in challenging mid-ocean ridge environments.

Geowissenschaftliches Kolloquium "Perspectives of non-seismic applied near-surface geophysics"

Online via Zoom:
https://uni-bremen.zoom.us/j/96524048625?pwd=VXAyWEVqNHo2Mzd3N1IrSVVrSVNIZz09